mICRO Minds

CS RTOS port to ATmega32

2012-12-06T16:35:00.000+05:30

A port of Glen Worstell's csRTOS to the ATmega32.

csRTOS is a priority-based co-operative scheduler that handles up to 8 tasks. This can be expanded to 16 tasks with little effort.

All user tasks, including ones run as the result of an ISR are assigned a fixed priority at compile time.

Semaphores are provided for protecting shared data.

Glen's code has several useful examples in setting up different types of tasks. This 2004 AVR design project is very well documented, which should enable you to easily modify the code for your application.

Corrected functions below thanks to curtvm.

csRTOS_ATmega32v4.zip has corrected saveTask(), restoreTask() and ADC example.

Download Code here

DTMF and GSM based location detector

2012-08-15T08:29:00.000+05:30

Abstract:
This is common problem to everyone to know the way or address of a particular area when you have been for a new place. To know the address we will go for a stranger or any receptionist(if available).

so to avoid this problem why can't we have a interacting system which shows the path of our desired location. It's just like the technology of IVRS system in our telecom support.

Real Time Clock based Industrial Automation (Energy Saver) using Dallas RTC and I2C protocol

2012-08-15T08:05:00.005+05:30

Abstract:

Advertising hoardings, commercial sign boards, and street lights are generally switched on at 6:30 pm and switched off at 10:00 am because nobody is available at the place in the morning to switch it off. But actual required time is 6:30pm to 11:30pm and 4:30am to 6:30am. Meantime i.e., from 11:30pm to 4:30am is not required, because the public flow on the roads is almost nil in this time. And from 6:30am to 10:00am is also not required as the sun light is available during this time. That means every day around nine hours of power is wasted. This project gives the best solution for electrical energy wastage. Also the manual operation of the lighting system is completely eliminated.

The Project AT89S8252 Microcontroller Based Energy saver for Commercial Lighting system with RTC DS1307 Interfacing is an interesting project which uses AT89S8252 microcontroller as its brain. This project is very useful for commercial sign boards, advertising boards, street lights for automation lighting system. This system switches on the lights only at preprogrammed timings. As the DS1307 Real Time Clock chip with battery back-up is used, there will be no disturbances for the programmed on/off timings even in power failures.

3X4 keypad is provided for entering the required timings. This keypad made this project user friendly. 4-digit seven segment display is provided to display the alarm times and current time. DS1307 is interfaced to the microcontroller for real timing performance. A 3V battery can be connected to DS1307 to avoid time disturbances caused by power failures.

AT89S8252 has inbuilt flash EPROM. Data stored remains in the memory even after power failure, as the memory ensures reading of the latest saved settings by the micro controller. It can retain data for more than ten years.

This project uses regulated 5V, 500mA power supply. Unregulated 12V DC is used for relay. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac out put of secondary of 230/12V step down transformer.

click here for schematic figure

Architecture of AVR

2012-07-13T18:37:00.001+05:30

The AVR microcontrollers are based on the advanced RISC architecture and consist of 32 x 8-bit general purpose working registers. Within one single clock cycle, AVR can take inputs from two general purpose registers and put them to ALU for carrying out the requested operation, and transfer back the result to an arbitrary register. The ALU can perform arithmetic as well as logical operations

over the inputs from the register or between the register and a constant. Single register operations like taking a complement can also be executed in ALU. We can see that AVR does not have any register like accumulator as in 8051 family of microcontrollers; the operations can be performed between any of the registers and can be stored in either of them.

AVR follows Harvard Architecture format in which the processor is equipped with separate memories and buses for Program and the Data information. Here while an instruction is being executed, the next instruction is pre-fetched from the program memory.

Since AVR can perform single cycle execution, it means that AVR can execute 1 million instructions per second if cycle frequency is 1MHz. The higher is the operating frequency of the controller, the higher will be its processing speed. We need to optimize the power consumption with processing speed and hence need to select the operating frequency accordingly.

There are two flavors for Atmega16 microcontroller:

1. Atmega16:- Operating frequency range is 0 – 16 MHz.

2. Atmega16L:- Operating frequency range is 0 – 8 MHz.

If we are using a crystal of 8 MHz = 8 x 10⁶ Hertz = 8 Million cycles, then AVR can execute 8 million instructions.

Naming Convention.!

The AT refers to Atmel the manufacturer, Mega means that the microcontroller belong to MegaAVR category, 16 signifies the memory of the controller, which is 16KB.

Architecture Diagram: Atmega16

Following points explain the building blocks of Atmega16 architecture:

· I/O Ports: Atmega16 has four (PORTA, PORTB, PORTC and PORTD) 8-bit input-output ports.

· Internal Calibrated Oscillator: Atmega16 is equipped with an internal oscillator for driving its clock. By default Atmega16 is set to operate at internal calibrated oscillator of 1 MHz. The maximum frequency of internal oscillator is 8Mhz. Alternatively, ATmega16 can be operated using an external crystal oscillator with a maximum frequency of 16MHz. In this case you need to modify the fuse bits.

ADC Interface: Atmega16 is equipped with an 8 channel ADC (Analog to Digital Converter) with a resolution of 10-bits. ADC reads the analog input for e.g., a sensor input and converts it into digital information which is understandable by the microcontroller.

· Timers/Counters: Atmega16 consists of two 8-bit and one 16-bit timer/counter. Timers are useful for generating precision actions for e.g., creating time delays between two operations.

· Watchdog Timer: Watchdog timer is present with internal oscillator. Watchdog timer continuously monitors and resets the controller if the code gets stuck at any execution action for more than a defined time interval.

· Interrupts: Atmega16 consists of 21 interrupt sources out of which four are external. The remaining are internal interrupts which support the peripherals like USART, ADC, Timers etc.

· USART: Universal Synchronous and Asynchronous Receiver and Transmitter interface is available for interfacing with external device capable of communicating serially (data transmission bit by bit).

General Purpose Registers: Atmega16 is equipped with 32 general purpose registers which are coupled directly with the Arithmetic Logical Unit (ALU) of CPU.

· Memory: Atmega16 consist of three different memory sections:

1. Flash EEPROM: Flash EEPROM or simple flash memory is used to store the program dumped or burnt by the user on to the microcontroller. It can be easily erased electrically as a single unit. Flash memory is non-volatile i.e., it retains the program even if the power is cut-off. Atmega16 is available with 16KB of in system programmable Flash EEPROM.

2. Byte Addressable EEPROM: This is also a nonvolatile memory used to store data like values of certain variables. Atmega16 has 512 bytes of EEPROM, this memory can be useful for storing the lock code if we are designing an application like electronic door lock.

3. SRAM: Static Random Access Memory, this is the volatile memory of microcontroller i.e., data is lost as soon as power is turned off. Atmega16 is equipped with 1KB of internal SRAM. A small portion of SRAM is set aside for general purpose registers used by CPU and some for the peripheral subsystems of the microcontroller.

· ISP: AVR family of controllers have In System Programmable Flash Memory which can be programmed without removing the IC from the circuit, ISP allows to reprogram the controller while it is in the application circuit.

· SPI: Serial Peripheral Interface, SPI port is used for serial communication between two devices on a common clock source. The data transmission rate of SPI is more than that of USART.

· TWI: Two Wire Interface (TWI) can be used to set up a network of devices, many devices can be connected over TWI interface forming a network, the devices can simultaneously transmit and receive and have their own unique address.

· DAC: Atmega16 is also equipped with a Digital to Analog Converter (DAC) interface which can be used for reverse action performed by ADC. DAC can be used when there is a need of converting a digital signal to analog signal.

Various microcontroller of MegaAVR series:

ATmega8 and Atmega32 are other members of MegaAVR series controllers. They are quite similar to ATmega16 in architecture. Low power version MegaAVR controllers are also available in markets. The following table shows the comparison between different members of MegaAVR family:

Part Name	ROM	RAM	EEPROM	I/0 Pins	Timer	Interrupts	Operation Voltage	Operating frequency	Packaging
ATmega8	8KB	1KB	512B	23	3	19	4.5-5.5 V	0-16 MHz	28
ATmega8L	8KB	1KB	512B	23	3	19	2.7-5.5 V	0-8 MHz	28
ATmega16	16KB	1KB	512B	32	3	21	4.5-5.5 V	0-16 MHz	40
ATmega16L	16KB	1KB	512B	32	3	21	2.7-5.5 V	0-8 MHz	40
ATmega32	32KB	2KB	1KB	32	3	21	4.5-5.5 V	0-16 MHz	40
ATmega32L	32KB	2KB	1KB	32	3	21	2.7-5.5 V	0-8 MHz	40

Architecture of AVR

2012-07-13T18:23:00.001+05:30

There are two flavors for Atmega16 microcontroller:

1. Atmega16:- Operating frequency range is 0 – 16 MHz.

2. Atmega16L:- Operating frequency range is 0 – 8 MHz.

If we are using a crystal of 8 MHz = 8 x 10⁶ Hertz = 8 Million cycles, then AVR can execute 8 million instructions.

Naming Convention.!

The AT refers to Atmel the manufacturer, Mega means that the microcontroller belong to MegaAVR category, 16 signifies the memory of the controller, which is 16KB.

Architecture Diagram: Atmega16

Following points explain the building blocks of Atmega16 architecture:

· I/O Ports: Atmega16 has four (PORTA, PORTB, PORTC and PORTD) 8-bit input-output ports.

· Timers/Counters: Atmega16 consists of two 8-bit and one 16-bit timer/counter. Timers are useful for generating precision actions for e.g., creating time delays between two operations.

· Interrupts: Atmega16 consists of 21 interrupt sources out of which four are external. The remaining are internal interrupts which support the peripherals like USART, ADC, Timers etc.

General Purpose Registers: Atmega16 is equipped with 32 general purpose registers which are coupled directly with the Arithmetic Logical Unit (ALU) of CPU.

· Memory: Atmega16 consist of three different memory sections:

· SPI: Serial Peripheral Interface, SPI port is used for serial communication between two devices on a common clock source. The data transmission rate of SPI is more than that of USART.

Various microcontroller of MegaAVR series:

Part Name	ROM	RAM	EEPROM	I/0 Pins	Timer	Interrupts	Operation Voltage	Operating frequency	Packaging
ATmega8	8KB	1KB	512B	23	3	19	4.5-5.5 V	0-16 MHz	28
ATmega8L	8KB	1KB	512B	23	3	19	2.7-5.5 V	0-8 MHz	28
ATmega16	16KB	1KB	512B	32	3	21	4.5-5.5 V	0-16 MHz	40
ATmega16L	16KB	1KB	512B	32	3	21	2.7-5.5 V	0-8 MHz	40
ATmega32	32KB	2KB	1KB	32	3	21	4.5-5.5 V	0-16 MHz	40
ATmega32L	32KB	2KB	1KB	32	3	21	2.7-5.5 V	0-8 MHz	40

Introduction to AVR.....

2012-07-13T17:35:00.000+05:30

AVR was developed in the year 1996 by Atmel Corporation. The architecture of AVR was developed by Alf-Egil Bogen and Vegard Wollan. AVR derives its name from its developers and stands for Alf-Egil Bogen Vegard Wollan RISC microcontroller, also known as Advanced Virtual RISC. The AT90S8515 was the first microcontroller which was based on AVR architecture however the first microcontroller to hit the commercial market was AT90S1200 in the year 1997.

AVR microcontrollers are available in three categories:

1. TinyAVR – Less memory, small size, suitable only for simpler applications

2. MegaAVR – These are the most popular ones having good amount of memory (upto 256 KB), higher number of inbuilt peripherals and suitable for moderate to complex applications.

3. XmegaAVR – Used commercially for complex applications, which require large program memory and high speed.

The following table compares the above mentioned AVR series of microcontrollers:

Series Name	Pins	Flash Memory	Special Feature
TinyAVR	6-32	0.5-8 KB	Small in size
MegaAVR	28-100	4-256KB	Extended peripherals
XmegaAVR	44-100	16-384KB	DMA , Event System included

What’s special about AVR?

They are fast: AVR microcontroller executes most of the instructions in single execution cycle. AVRs are about 4 times faster than PICs, they consume less power and can be operated in different power saving modes. Let’s do the comparison between the three most commonly used families of microcontrollers.

	8051	PIC	AVR
SPEED	Slow	Moderate	Fast
MEMORY	Small	Large	Large
ARCHITECTURE	CISC	RISC	RISC
ADC	Not Present	Inbuilt	Inbuilt
Timers	Inbuilt	Inbuilt	Inbuilt
PWM Channels	Not Present	Inbuilt	Inbuilt

AVR is an 8-bit microcontroller belonging to the family of Reduced Instruction Set Computer (RISC). In RISC architecture the instruction set of the computer are not only fewer in number but also simpler and faster in operation. The other type of categorization is CISC (Complex Instruction Set Computers). We will explore more on this when we will learn about the architecture of AVR microcontrollers in following section.

Let’s see what all this means. What is 8-bit? This means that the microcontroller is capable of transmitting and receiving 8-bit data. The input/output registers available are of 8-bits. The AVR family controllers have register based architecture which means that both the operands for an operation are stored in a register and the result of the operation is also stored in a register. Following figure shows a simple example performing OR operation between two input registers and storing the value in Output Register.

The CPU takes values from two input registers INPUT-1 and INPUT-2, performs the logical operation and stores the value into the OUTPUT register. All this happens in 1 execution cycle.

In our journey with the AVR we will be working on ATmega16 microcontroller, which is a 40-pin IC and belongs to the megaAVR category of AVR family.

Some of the features of Atmega16 are:

16KB of Flash memory

· 1KB of SRAM

· 512 Bytes of EEPROM

· Available in 40-Pin DIP

· 8-Channel 10-bit ADC

· Two 8-bit Timers/Counters

· One 16-bit Timer/Counter

· 4 PWM Channels

· In System Programmer (ISP)

· Serial USART

· SPI Interface

· Digital to Analog Comparator.

Intel .hex file format

2012-06-05T12:52:00.002+05:30

The Intel HEX file is an ASCII text file with lines of text that follow the Intel HEX file format. Each line in an Intel HEX file contains one HEX record. These records are made up of hexadecimal numbers that represent machine language code and/or constant data. Intel HEX files are often used to transfer the program and data that would be stored in a ROM or EPROM. Most EPROM programmers or emulators can use Intel HEX files.

Record Format

An Intel HEX file is composed of any number of HEX records. Each record is made up of five fields that are arranged in the following format:

:llaaaatt[dd...]cc

Each group of letters corresponds to a different field, and each letter represents a single hexadecimal digit. Each field is composed of at least two hexadecimal digits-which make up a byte-as described below:

: is the colon that starts every Intel HEX record.
ll is the record-length field that represents the number of data bytes (dd) in the record.
aaaa is the address field that represents the starting address for subsequent data in the record.
tt is the field that represents the HEX record type, which may be one of the following:
00 - data record
01 - end-of-file record
02 - extended segment address record
04 - extended linear address record
05 - start linear address record (MDK-ARM only)
dd is a data field that represents one byte of data. A record may have multiple data bytes. The number of data bytes in the record must match the number specified by the ll field.
cc is the checksum field that represents the checksum of the record. The checksum is calculated by summing the values of all hexadecimal digit pairs in the record modulo 256 and taking the two's complement.

Data Records

The Intel HEX file is made up of any number of data records that are terminated with a carriage return and a linefeed. Data records appear as follows:

:10246200464C5549442050524F46494C4500464C33

This record is decoded as follows:

:10246200464C5549442050524F46494C4500464C33

||||||||||| CC->Checksum

|||||||||DD->Data

|||||||TT->Record Type

|||AAAA->Address

|LL->Record Length

:->Colon

where:

10 is the number of data bytes in the record.
2462 is the address where the data are to be located in memory.
00 is the record type 00 (a data record).
464C...464C is the data.
33 is the checksum of the record.

Extended Linear Address Records (HEX386)

Extended linear address records are also known as 32-bit address records and HEX386 records. These records contain the upper 16 bits (bits 16-31) of the data address. The extended linear address record always has two data bytes and appears as follows:

:02000004FFFFFC

where:

02 is the number of data bytes in the record.
0000 is the address field. For the extended linear address record, this field is always 0000.
04 is the record type 04 (an extended linear address record).
FFFF is the upper 16 bits of the address.
FC is the checksum of the record and is calculated as
01h + NOT(02h + 00h + 00h + 04h + FFh + FFh).

When an extended linear address record is read, the extended linear address stored in the data field is saved and is applied to subsequent records read from the Intel HEX file. The linear address remains effective until changed by another extended address record.

The absolute-memory address of a data record is obtained by adding the address field in the record to the shifted address data from the extended linear address record. The following example illustrates this process..

Address from the data record's address field 2462

Extended linear address record data field FFFF

--------

Absolute-memory address FFFF2462

Extended Segment Address Records (HEX86)

Extended segment address records-also known as HEX86 records-contain bits 4-19 of the data address segment. The extended segment address record always has two data bytes and appears as follows:

:020000021200EA

where:

02 is the number of data bytes in the record.
0000 is the address field. For the extended segment address record, this field is always 0000.
02 is the record type 02 (an extended segment address record).
1200 is the segment of the address.
EA is the checksum of the record and is calculated as
01h + NOT(02h + 00h + 00h + 02h + 12h + 00h).

When an extended segment address record is read, the extended segment address stored in the data field is saved and is applied to subsequent records read from the Intel HEX file. The segment address remains effective until changed by another extended address record.

The absolute-memory address of a data record is obtained by adding the address field in the record to the shifted-address data from the extended segment address record. The following example illustrates this process.

Address from the data record's address field 2462

Extended segment address record data field 1200

--------

Absolute memory address 00014462

Start Linear Address Records (MDK-ARM only)

Start linear address records specify the start address of the application. These records contain the full linear 32 bit address. The start linear address record always has four data bytes and appears as follows:

:04000005000000CD2A

where:

04 is the number of data bytes in the record.
0000 is the address field. For the start linear address record, this field is always 0000.
05 is the record type 05 (a start linear address record).
000000CD is the 4 byte linear start address of the application.
2A is the checksum of the record and is calculated as
01h + NOT(04h + 00h + 00h + 05h + 00h + 00h + 00h + CDh).

The Start Linear Address specifies the address of the __main (pre-main) function but not the address of the startup code which usually calls __main after calling SystemInit(). An odd linear start address specifies that __main is compiled for the Thumb instruction set.

The Start Linear Address Record can appear anywhere in hex file. In most cases this record can be ignored because it does not contain information which is needed to program flash memory.

End-of-File (EOF) Records

An Intel HEX file must end with an end-of-file (EOF) record. This record must have the value 01 in the record type field. An EOF record always appears as follows:

:00000001FF

where:

00 is the number of data bytes in the record.
0000 is the address where the data are to be located in memory. The address in end-of-file records is meaningless and is ignored. An address of 0000h is typical.
01 is the record type 01 (an end-of-file record).
FF is the checksum of the record and is calculated as
01h + NOT(00h + 00h + 00h + 01h).

Example Intel HEX File

Following is an example of a complete Intel HEX file:

:10001300AC12AD13AE10AF1112002F8E0E8F0F2244

:10000300E50B250DF509E50A350CF5081200132259

:03000000020023D8

:0C002300787FE4F6D8FD7581130200031D

:10002F00EFF88DF0A4FFEDC5F0CEA42EFEEC88F016

:04003F00A42EFE22CB

:00000001FF

DS1307 RTC interfacing with 8051

2012-05-28T17:17:00.001+05:30

Download as pdf file

Abstract: This application note provides information on how to interface a DS1307 real-time clock (RTC) to a microcontroller and provides some example code for accessing the part.

Introduction

The DS1307 Serial Real Time Clock, which incorporates a 2-wire serial interface, can be controlled using an 8051-compatible microcontroller. The DS1307 in this example is connected directly to two of the I/O ports on a DS5000 microcontroller and the 2-wire handshaking is handled by low-level drivers, which are discussed in this application note.

DS1307 Description

The DS1307 Serial Real Time Clock is a low-power, full BCD clock/calendar plus 56 bytes of nonvolatile SRAM. Address and data are transferred serially via the 2-wire bi-directional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for months with less than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1307 has a built-in power sense circuit which detects power failures and automatically switches to the battery supply.

DS1307 Operation

The DS1307 operates as a slave device on the serial bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. Subsequent registers can be accessed sequentially until a STOP condition is executed. The START and STOP conditions are generated using the low level drives, SEND_START and SEND_STOP found in the attached DS5000 code. Also the subroutines SEND_BYTE and READ_BYTE provide the 2-wire handshaking required for writing and reading 8-bit words to and from the DS1307.

Hardware Configuration

Figure 1. Typical 2-wire bus configuration.

The system is configured as shown in Figure 1. The DS1307 has the 2-wire bus connected to two I/O port pins of the DS5000: SCL - P1.0, SDA - P1.1. The V_DD voltage is 5V, R_P = 5KΩ and the DS5000 is using a 12-MHz crystal. The other peripheral device could be any other device that recognizes the 2-wire protocol, such as the DS1621 Digital Thermometer andThermostat. The interface with the D5000 was accomplished using the DS5000T Kit hardware and software. Thisdevelopment kit allows the PC to be used as a dumb terminal using the DS5000's serial ports to communicate with the keyboard and monitor.

The following bus protocol has been defined (see Figure 2).

During data transfer, the data line must remain stable whenever the clock line is high. Changes in the data line while the clock line is high will be interpreted as control signals.

Accordingly, the following bus conditions have been defined:

Start data transfer: A change in the state of the data line from high to low, while the clock line is high, defines a START condition.

Stop data transfer: A change in the state of the data line from low to high, while the clock line is high, defines the STOP condition.

Data valid: The state of the data line represents valid data when, after a START condition, the data line is stable for the duration of the high period of the clock signal. The data on the line must be changed during the low period of the clock signal. There is one clock pulse per bit of data.

Each data transfer is initiated with a START condition and terminated with a STOP condition. The number of data bytes transferred between the START and the STOP conditions is not limited, and is determined by the master device. The information is transferred byte-wise and each receiver acknowledges with a ninth bit.

Acknowledge: Each receiving device, when addressed, is obliged to generate an acknowledge after the reception of each byte. The master device must generate an extra clock pulse which is associated with this acknowledge bit.

A device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is stable low during the high period of the acknowledge related clock pulse. Of course, setup and hold times must be taken into account. A master must signal an end of data to the slave by not generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case, the slave must leave the data line high to enable the master to generate the STOP condition.

Figure 2 details how data transfer is accomplished on the 2-wire bus. Depending on the state of the R/active-low W bit, two types of data transfer are possible:

Data transfer from a master transmitter to a slave receiver. The first byte transmitted by the master is the slave address. Next follows a number of data bytes. The slave returns an acknowledge bit after each received byte. Data is transferred with the most significant bit (MSB) first.
Data transfer from a slave transmitter to a master receiver. The first byte (the slave address) is transmitted by the master. The slave then returns an acknowledge bit. This is followed by the slave transmitting a number of data bytes. The master returns an acknowledge bit after all received bytes other than the last byte. At the end of the last received byte, a not acknowledge is returned.

Figure 2. Data transfer on 2-wire serial bus.

The master device generates all of the serial clock pulses and the START and STOP conditions. A transfer is ended with a STOP condition or with a repeated START condition. Since a repeated START condition is also the beginning of the next serial transfer, the bus will not be released. Data is transferred with the most significant bit (MSB) first.

The DS1307 may operate in the following two modes:

Figure 4. Data read—slave transmitter mode.

Figure 3. Data write—slave receiver mode.

Slave receiver mode (DS1307 write mode): Serial data and clock are received through SDA and SCL. After each byte is received, an acknowledge bit is transmitted. START and STOP conditions are recognized as the beginning and end of a serial transfer. Address recognition is performed by hardware after reception of the slave address and direction bit (see Figure 3). The address byte is the first byte received after the start condition is generated by the master. The address byte contains the 7-bit DS1307 address, which is 1101000, followed by the direction bit (R/active-low W) which for a write is a 0. After receiving and decoding the address byte, the DS1307 outputs an acknowledge on the SDA line. After the DS1307 acknowledges the slave address + write bit, the master transmits a register address to the DS1307. This will set the register pointer on the DS1307. The master will then begin transmitting each byte of data with the DS1307 acknowledging each byte received. The master will generate a stop condition to terminate the data write.
Slave transmitter mode (DS1307 read mode): The first byte is received and handled as in the slave receiver mode. However, in this mode, the direction bit will indicate that the transfer direction is reversed. Serial data is transmitted on SDA by the DS1307 while the serial clock is input on SCL. START and STOP conditions are recognized as the beginning and end of a serial transfer (See Figure 4). The address byte is the first byte received after the start condition is generated by the master. The address byte contains the 7-bit DS1307 address, which is 1101000, followed by the direction bit (R/active-low W), which for a read is a 1. After receiving and decoding the address byte, the DS1307 inputs an acknowledge on the SDA line. The DS1307 then begins to transmit data starting with the register address pointed to by the register pointer. If the register pointer is not written to before the initiation of a read mode, the first address that is read is the last one stored in the register pointer. The DS1307 must be sent a Not-Acknowledge bit by the master to terminate a read.

Software Operation

DS5000 Interface

The software presented in Appendix 1 is written to interface the DS5000 with the DS1307 over the 2-wire interface. The DS5000 was programmed using Dallas Semiconductor's DS5000T Evaluation Kit, which allows a PC to be used as a dumb terminal. The KIT5K software environment supplied with the DS5000T Evaluation Kit provides a high-level interface for loading application software to the DS5000 or for setting its configuration parameters via the Program command. The KIT5K software includes a dumb terminal emulator to allow users to run application software in the DS5000, which communicates with the user via a PC COM port.

DS1307 Source Code

The first section of the code found in the Appendix is used to configure the DS5000 for serial communication with the PC. Also at the beginning of the code is the MASTER_CONTROLLER subroutine which is used to control the demonstration software.

The subroutines that immediately follow the MASTER_CONTROLLER subroutine are the low level drivers for controlling the 2-wire interface. They are not specific to the DS1307 but can be used with any 2-wire compatible slave-only device. These subroutines are:

SEND_START

This subroutine is used to generate the Start condition on the 2-wire bus.

SEND_STOP

This subroutine is used to generate the Stop condition on the 2-wire bus.

SEND_BYTE

This subroutine sends an 8-bit word, MSB first, over the 2-wire bus with a 9^th clock pulse for the Acknowledge pulse.

READ_BYTE

This subroutine reads an 8-bit word over the 2-wire bus. It checks for the LASTREAD flag to be cleared indicating when the last read from the slave device is to occur. If it is not the last read, the DS5000 sends an Acknowledge pulse on the 9^th clock and if it is the last read from the slave device, the DS5000 sends a Not-Acknowledge.

SCL_HIGH

This subroutine transitions the SCL line low-to-high and ensures the SCL line is high before continuing.

DELAY and DELAY_4

These two subroutines have been included to ensure that the 2-wire bus timing is maintained.

The rest of the code included in the appendix is specifically designed to demonstrate the functions of the DS1307. The functions that are demonstrated are:

Setting Time

The time is read in from the keyboard and stored in the DS5000 scratchpad memory. It is then transferred, over the 2-wire interface, to the DS1307.

Set RAM

A single hex byte is read in from the keyboard and written to the entire user RAM of the DS1307.

Read Date/Time

The date and time are read, over the 2-wire bus, and stored in the DS5000 scratchpad memory. It is then written to the screen. This continues until a key is pressed on the keyboard.>

Read RAM

The entire user RAM of the DS1307 is read into the DS5000 scratchpad memory and then written to the PC monitor.

OSC On/ OSC Off

The DS1307 clock oscillator can be turned on or off.

SQW/OUT On/ SQW/OUT Off

The SQW/OUT can be turned on or off. It will toggle at 1 Hz.

Conclusion

It has been shown that it is very straight forward to interface the DS1307 or any other 2-wire slave device to an 8051-compatible microcontroller. The only concern must be that the 2-wire timing specification is not violated by the low level drivers on the microcontroller. The delay subroutines have been inserted into the code for this purpose. The values in Table 1 are the actual timing parameters observed in the hardware setup used to develop this application note.

Table 1. AC Electrical Characteristics

Parameter	Symbol	Actual	Units
SCL Clock Frequency	f_SCL	59	kHz
Bus Free Time Between a STOP and START condition	t_BUF	5.7	µs
Hold Time (repeated) START Condition	t_HD:STA	6.2	µs
LOW Period of SCL Clock	t_LOW	10.5	µs
HIGH Period of SCL Clock	t_HIGH	6.5M	µs
Set-up Time for a Repeated START Condition	t_SU:STA	5.3	µs
Data Hold Time	t_HD:DAT	5.5	µs
Data Set-up Time	t_SU:DAT	3.1	µs
Set-up Time for STOP Condition	t_SU:STO	5.4	µs

Appendix: DS1307.ASM

; Program DS1307.ASM

;

; This program responds to commands received over the serial

; port to set the date/time as well as RAM data on the DS1307

; using a DS5000 as a controller

;

CR EQU 0DH

LF EQU 0AH

MCON EQU 0C6H

TA EQU 0C7H

SCL BIT P0.0

SDA BIT P0.1

TRIG BIT P0.2

DS1307W EQU 0D0H

DS1307R EQU 0D1H

FLAGS DATA 20H

LASTREAD BIT FLAGS.0

_12_24 BIT FLAGS.1

PM_AM BIT FLAGS.2

OSC BIT FLAGS.3

SQW BIT FLAGS.4

ACK BIT FLAGS.5

BUS_FAULT BIT FLAGS.6

_2W_BUSY BIT FLAGS.7

BITCOUNT DATA 21H

BYTECOUNT DATA 22H

BYTE DATA 23H

CSEG AT 0

AJMP START

;

CSEG AT 30H

;*************************************************************

;*** RESET GOES HERE TO START PROGRAM ****

;*************************************************************

START:

MOV TA,#0AAH ; Timed

MOV TA,#55H ; access.

MOV PCON,#0 ; Reset watchdog timer.

MOV MCON,#0F8H ; Turn off CE2 for memory access.

MOV SP,#70H ; Position stack above buffer.

MOV IE,#0

MOV TMOD,#20H ; Initialize the

MOV TH1,#0FAH ; serial port

MOV TL1,#0FAH ; for 9600

ORL PCON,#80H ; baud.

MOV SCON,#52H

MOV TCON,#40H

;MOV R0,#0

;MOV R1,#0

;DJNZ R0,$

;DJNZ R1,$-2

SETB SDA ; ENSURE SDA HIGH

LCALL SCL_HIGH ; ENSURE SCL HIGH

CLR ACK ; CLEAR STATUS FLAGS

CLR BUS_FAULT

CLR _2W_BUSY

;-----------------------------------------------------------------------

; THIS IS THE MASTER CONTROLLER LOOP

;-----------------------------------------------------------------------

MASTER_CONTROLLER:

MOV BYTECOUNT,#10H

FORM_FEED: MOV A,#LF ; CLEAR SCREEN FOR MAIN MENU

LCALL WRITE_DATA

DJNZ BYTECOUNT,FORM_FEED

MOV DPTR, #TEXT0 ; PUT MAIN MENU ON SCREEN

LCALL WRITE_TEXT

MOV DPTR, #TEXT3

LCALL WRITE_TEXT

LCALL READ_DATA

CLR ACC.5 ; CONVERT ACC TO UPPER CASE

CJNE A,#'A',NOTA ; CALL SET CLOCK FUNCTION

LCALL SET_CLOCKM

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTA: CJNE A,#'B',NOTB ; CALL SET RAM FUNCTION AND

LCALL SET_RAM ; CALL READ RAM FUNCTION

LCALL READ_RAM

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTB: CJNE A,#'C',NOTC ; CALL READ CLOCK FUNCTION

LCALL READ_CLOCK

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTC: CJNE A,#'D',NOTD ; CALL READ RAM FUNCTION

LCALL READ_RAM

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTD: CJNE A,#'E',NOTE ; CALL OSC CONTROL FUNCTION

CLR OSC ; CLR OSC FLAG - ON

LCALL OSC_CONTROL

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTE: CJNE A,#'F',NOTF ; CALL OSC CONTROL FUNCTION

SETB OSC ; SET OSC FLAG - OFF

LCALL OSC_CONTROL

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTF: CJNE A,#'G',NOTG ; CALL SWQ CONTROL FUNCTION

CLR SQW ; CLR SQW FLAG - ON

LCALL SQW_CONTROL_1HZ

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTG: CJNE A,#'H',NOTH ; CALL SWQ CONTROL FUNCTION

CLR SQW ; CLR SQW FLAG - ON

LCALL SQW_CONTROL_4KHZ

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTH: CJNE A,#'I',NOTI ; CALL SWQ CONTROL FUNCTION

CLR SQW ; CLR SQW FLAG - ON

LCALL SQW_CONTROL_8KHZ

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTI: CJNE A,#'J',NOTJ ; CALL SWQ CONTROL FUNCTION

CLR SQW ; CLR SQW FLAG - ON

LCALL SQW_CONTROL_32KHZ

JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

NOTJ: CJNE A,#'K',NOTK ; CALL SWQ CONTROL FUNCTION

SETB SQW ; SET SQW FLAG - OFF

LCALL SQW_CONTROL_1HZ

JMP MASTER_CONTROLLER

NOTK: CJNE A,#'L',NOTL

LCALL SET_RAM_UNQ

LCALL READ_RAM

NOTL: JMP MASTER_CONTROLLER ; RETURN TO MAIN MENU

;-----------------------------------------------------------------------

; THIS SUB SENDS THE START CONDITION

;-----------------------------------------------------------------------

SEND_START: ;

SETB _2W_BUSY ; INDICATE THAT 2WIRE OPERATION IN PROGRESS

CLR ACK ; CLEAR STATUS FLAGS

CLR BUS_FAULT

JNB SCL,FAULT ; CHECK FOR BUS CLEAR

JNB SDA,FAULT ; BEGIN START CONDITION

SETB SDA ;

LCALL SCL_HIGH ; SDA

CLR SDA

;

LCALL DELAY ; SCL ^START CONDITION

CLR SCL

RET

FAULT:

SETB BUS_FAULT ; SET FAULT STATUS

RET ; AND RETURN

;-----------------------------------------------------------------------

; THIS SUB SENDS THE STOP CONDITION

;-----------------------------------------------------------------------

SEND_STOP: ;

CLR SDA ; SDA

LCALL SCL_HIGH ;

SETB SDA ; SCL ^STOP CONDITION

CLR _2W_BUSY

RET

;-----------------------------------------------------------------------

; THIS SUB SENDS ONE BYTE OF DATA TO THE DS1307

;-----------------------------------------------------------------------

SEND_BYTE:

MOV BITCOUNT,#08H ; SET COUNTER FOR 8 BITS

SB_LOOP:

JNB ACC.7,NOTONE ; CHECK TO SEE IF BIT 7 OF ACC IS A 1

SETB SDA ; SET SDA HIGH (1)

JMP ONE

NOTONE:

CLR SDA ; CLR SDA LOW (0)

ONE:

LCALL SCL_HIGH ; TRANSITION SCL LOW-TO-HIGH

RL A ; ROTATE ACC LEFT ONE BIT

CLR SCL ; TRANSITION SCL HIGH-TO-LOW

DJNZ BITCOUNT,SB_LOOP ; LOOP FOR 8 BITS

SETB SDA ; SET SDA HIGH TO LOOK FOR ACKNOWLEDGE PULSE

LCALL SCL_HIGH ; TRASITION SCL LOW-TO-HIGH

CLR ACK ; CLEAR ACKNOWLEDGE FLAG

JNB SDA,SB_EX ; CHECK FOR ACK OR NOT ACK

SETB ACK ; SET ACKNOWLEDGE FLAG FOR NOT ACK

SB_EX:

LCALL DELAY ; DELAY FOR AN OPERATION

CLR SCL ; TRANSITION SCL HIGH-TO-LOW

LCALL DELAY ; DELAY FOR AN OPERATION

RET

;-----------------------------------------------------------------------

; THIS SUB READS ONE BYTE OF DATA FROM THE DS1307

;-----------------------------------------------------------------------

READ_BYTE:

MOV BITCOUNT,#008H ; SET COUNTER FOR 8 BITS OF DATA

MOV A,#00H ;

SETB SDA ; SET SDA HIGH TO ENSURE LINE FREE

READ_BITS:

LCALL SCL_HIGH ; TRANSITION SCL LOW-TO-HIGH

MOV C,SDA ; MOVE DATA BIT INTO CARRY BIT \

RLC A ; ROTATE CARRY BIT INTO ACC.0

CLR SCL ; TRANSITION SCL HIGH-TO-LOW

DJNZ BITCOUNT,READ_BITS ; LOOP FOR 8 BITS

JB LASTREAD,ACKN ; CHECK TO SEE IF THIS IS THE LAST READ

CLR SDA ; IF NOT LAST READ SEND ACKNOWLEDGE BIT

ACKN:

LCALL SCL_HIGH ; PULSE SCL TO TRANSIMIT ACKNOWLEDGE

CLR SCL ; OR NOT ACKNOWLEDGE BIT

RET

;----------------------------------------------------------------------- ;

; THIS SUB SETS THE CLOCK LINE HIGH

;-----------------------------------------------------------------------

SCL_HIGH:

SETB SCL ; SET SCL HIGH

JNB SCL,$ ; LOOP UNTIL STRONG 1 ON SCL

RET

;----------------------------------------------------------------------- ;

; THIS SUB DELAY THE BUS

;-----------------------------------------------------------------------

DELAY:

NOP ; DELAY FOR BUS TIMING

RET

;-----------------------------------------------------------------------

; THIS SUB DELAYS 4 CYCLES

;-----------------------------------------------------------------------

DELAY_4:

NOP ; DELAY FOR BUS TIMING

NOP

RET

;-----------------------------------------------------------------------

; THIS SUB SETS THE CLOCK (MANUAL)

;-----------------------------------------------------------------------

SET_CLOCKM:

MOV R1,#2EH ; SET R1 TO SCRATCHPAD MEMORY FOR DATE/TIME

MOV DPTR, #YEAR ; GET THE DATE/TIME INFORMATION FROM THE

LCALL WRITE_TEXT ; USER. WRITE THE DATE/TIME TO SCRATCHPAD

LCALL READ_BCD ; MEMORY

MOV @R1,A

DEC R1

MOV DPTR, #MONTH

LCALL WRITE_TEXT

LCALL READ_BCD

MOV @R1,A

DEC R1

MOV DPTR, #DAY

LCALL WRITE_TEXT

LCALL READ_BCD

MOV @R1,A

DEC R1

MOV DPTR, #DAYW

LCALL WRITE_TEXT

LCALL READ_BCD

ANL A, #7

MOV @R1,A

DEC R1

MOV DPTR, #HOUR

LCALL WRITE_TEXT

LCALL READ_BCD

MOV @R1,A

DEC R1

MOV DPTR, #MINUTE

LCALL WRITE_TEXT

LCALL READ_BCD

MOV @R1,A

DEC R1

MOV DPTR, #SECOND

LCALL WRITE_TEXT

LCALL READ_BCD

MOV @R1,A

MOV R1,#28H ; POINT TO BEGINNING OF CLOCK DATA IN SCRATCHPAD MEMORY

LCALL SEND_START ; SEND 2WIRE START CONDITION

MOV A,#DS1307W ; SEND DS1307 WRITE COMMAND

LCALL SEND_BYTE

MOV A,#00H ; SET DATA POINTER TO REGISTER 00H ON

LCALL SEND_BYTE ; THE DS1307

SEND_LOOP:

MOV A,@R1 ; MOVE THE FIRST BYTE OF DATA TO ACC

LCALL SEND_BYTE ; SEND DATA ON 2WIRE BUT

INC R1

CJNE R1,#2FH,SEND_LOOP ; LOOP UNTIL CLOCK DATA SENT TO DS1307

LCALL SEND_STOP ; SEND 2WIRE STOP CONDITION

RET

;-----------------------------------------------------------------------

; THIS SUB SETS THE DS1307 USER RAM TO THE VALUE IN 'BYTE'

;-----------------------------------------------------------------------

SET_RAM:

MOV R1,#08H ; POINTER TO BEGINNING OF DS1307 USER RAM

MOV DPTR, #TEXT5 ; MESSAGE TO ENTER DATA BYTE

LCALL WRITE_TEXT ;

LCALL READ_BCD ; READ BYTE FROM KEYBOARD

MOV BYTE,A ; AND STORE IN 'BYTE'

LCALL SEND_START ; SEND 2WIRE START CONDITION

MOV A,#DS1307W ; LOAD DS1307 WRITE COMMAND

LCALL SEND_BYTE ; SEND WRITE COMMAND

MOV A,#08H ; SET DS1307 DATA POINTER TO BEGINNING

LCALL SEND_BYTE ; OF USER RAM - 08H

SEND_LOOP2:

MOV A,BYTE ; WRITE BYTE TO ENTIRE RAM SPACE

LCALL SEND_BYTE ; WHICH IS 08H TO 37H

INC R1

CJNE R1,#040H,SEND_LOOP2 ; LOOP UNTIL RAM FILLED

LCALL SEND_STOP ; SEND 2WIRE STOP CONTION

RET

;-----------------------------------------------------------------------

; THIS SUB SETS THE DS1307 USER RAM TO THE UNIQUE PATTERN

;-----------------------------------------------------------------------

SET_RAM_UNQ:

MOV R1,#08H ; POINTER TO BEGINNING OF DS1307 USER RAM

LCALL SEND_START ; SEND 2WIRE START CONDITION

MOV A,#DS1307W ; LOAD DS1307 WRITE COMMAND

LCALL SEND_BYTE ; SEND WRITE COMMAND

MOV A,#08H ; SET DS1307 DATA POINTER TO BEGINNING

LCALL SEND_BYTE ; OF USER RAM - 08H

SEND_LOOP3:

LCALL SEND_BYTE ; WHICH IS 08H TO 37H

INC R1

INC A

CJNE R1,#040H,SEND_LOOP3 ; LOOP UNTIL RAM FILLED

LCALL SEND_STOP ; SEND 2WIRE STOP CONTION

RET

;-----------------------------------------------------------------------

; THIS SUB READS THE DS1307 RAM AND WRITES IT TO THE SCRATCH PAD MEMORY

;-----------------------------------------------------------------------

READ_RAM:

MOV DPTR,#TEXT4 ; SEND KEY PRESS MSG

LCALL WRITE_TEXT

MOV R1,#30H ; START OF RAM REGS IN SCRATCH PAD

MOV BYTECOUNT,#00H ; COUNTER FOR 56 RAM BYTES

CLR LASTREAD ; FLAG TO CHECK FOR LAST READ

LCALL SEND_START ; SEND 2WIRE START CONDITION

MOV A,#DS1307W ; SEND DS1307 WRITE COMMAND

LCALL SEND_BYTE

MOV A,#08H ; SET POINTER TO REG 08H ON

;DS1307

LCALL SEND_BYTE

LCALL SEND_STOP ; SEND STOP CONDITION

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307R ; SEND DS1307 READ COMMAND

LCALL SEND_BYTE

READ_LOOP2:

MOV A,BYTECOUNT ; CHECK TO SEE OF DOING LAST READ

CJNE A,#37H,NOT_LAST2

SETB LASTREAD ; IF LAST READ SET LASTREAD FLAG

NOT_LAST2:

LCALL READ_BYTE ; READ A BYTE OF DATA

MOV @R1,A ; MOVE DATA INTO SCRATCHPAD MEMORY

INC R1 ; INC POINTERS

INC BYTECOUNT

MOV A,BYTECOUNT

CJNE A,#38H,READ_LOOP2 ; LOOP FOR ENTIRE DS1307 RAM

LCALL SEND_STOP ; SEND 2WIRE STOP CONDITION

LCALL DISP_RAM ; DISPLAY DATA IN SCRATCHPAD MEMORY

JNB RI,$ ;WAIT UNTIL A KEY IS PRESSED

CLR RI

RET

;-----------------------------------------------------------------------

; THIS SUB DISPLAYS THE RAM DATA SAVED IN SCRATCHPAD MEMORY

;-----------------------------------------------------------------------

DISP_RAM:

MOV R1,#30H ;START OF RAM IN SCRATCHPAD

;MEMORY

MOV BITCOUNT,#00H

MOV DPTR,#TEXT6 ;DISPLAY TABLE HEADING

LCALL WRITE_TEXT

DISP_ADDR:

LCALL DISP_LOC ; DISPLAY VALUE OF CURRENT RAM LOCATION

DIS_LOOP:

MOV A,@R1 ; DISPLAY RAM DATA SAVED IN SCRATCHPAD

LCALL WRITE_BCD ; CONVERT TO BCD FORMAT AND DISPLAY

INC R1

INC BITCOUNT

MOV A,#20H ; SPACE BETWEEN DATA BYTES

LCALL WRITE_DATA

MOV A,BITCOUNT

CJNE A,#08H,DIS_LOOP ; LINE FEED AFTER 8 BYTES OF DATA

MOV BITCOUNT,#00H

MOV DPTR,#TEXT3 ; 'CR,LF'

LCALL WRITE_TEXT

CJNE R1,#68H,DISP_ADDR ; DISPLAY DATA FOR 56 BYTES OF RAM

RET

;----------------------------------------------------------------------- ;

; THIS SUB WRITES THE RAM LOCATION OF THE DATA

;-----------------------------------------------------------------------

DISP_LOC:

MOV A,R1 ; DISPLAY THE HEX VALUE FOR THE DATA

ADD A,#-28H ; IN THE DS1307 RAM SPACE

LCALL WRITE_BCD ; CONVERTS SCRATCHPAD ADDRESS

MOV A,#20H ; INTO DS1307 RAM ADDRESS

LCALL WRITE_DATA

MOV A,#20H

LCALL WRITE_DATA

MOV A,#20H

LCALL WRITE_DATA

RET

;-----------------------------------------------------------------------

; THIS SUB READS THE CLOCK AND WRITES IT TO THE SCRATCH PAD MEMORY ;

;-----------------------------------------------------------------------

READ_CLOCK:

MOV DPTR,#TEXT4 ; KEY PRESS MSG

LCALL WRITE_TEXT

READ_AGAIN:

MOV R1,#28H ; START OF CLOCK REG IN SCRATCHPAD

MOV BYTECOUNT,#00H ; COUNTER UP TO 8 BYTES FOR CLOCK

CLR LASTREAD ; FLAG TO CHECK FOR LAST READ

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 00H ON DS1307

LCALL SEND_BYTE

MOV A,#00H

LCALL SEND_BYTE

LCALL SEND_STOP ; SEND STOP CONDITION

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307R ; SEND READ COMMAND TO DS1307

LCALL SEND_BYTE

READ_LOOP:

MOV A,BYTECOUNT ; CHECK TO SEE OF DOING LAST READ

CJNE A,#07H,NOT_LAST

SETB LASTREAD ; SET LASTREAD FLAG

NOT_LAST:

LCALL READ_BYTE ; READ A BYTE OF DATA

MOV @R1,A ; MOVE DATA IN SCRATCHPAD MEMORY

MOV A,BYTECOUNT ; CHECK TO SEE IF READING SECONDS REG

CJNE A,#00H,NOT_FIRST

CLR OSC ; CLR OSC FLAG

MOV A,@R1 ; MOVE SECONDS REG INTO ACC

JNB ACC.7,NO_OSC ; JUMP IF BIT 7 OF IS A 0

SETB OSC ; SET OSC FLAG, BIT 7 IS A 1

CLR ACC.7 ; CLEAR BIT 7 FOR DISPLAY

; PURPOSES

MOV @R1,A ; MOVE DATA BACK TO SCRATCHPAD

NO_OSC:

NOT_FIRST:

INC R1 ; INC COUNTERS

INC BYTECOUNT

MOV A,BYTECOUNT

CJNE A,#08H,READ_LOOP ; LOOP FOR ENTIRE CLOCK REGISTERS

LCALL SEND_STOP ; SEND 2WIRE STOP CONDITION

LCALL DISP_CLOCK ; DISPLAY DATE/TIME FROM SCRATCHPAD

JNB RI,READ_AGAIN ; READ AND DISPLAY UNTIL A KEY IS PRESSED

CLR RI

RET

;-----------------------------------------------------------------------

; THIS SUB DISPLAYS THE DATE AND TIME SAVED IN SCRATCHPAD MEMORY

;-----------------------------------------------------------------------

DISP_CLOCK:

MOV DPTR,#TEXT1 ; DATE:

LCALL WRITE_TEXT

MOV R1,#2DH ; MONTH

MOV A,@R1

LCALL WRITE_BCD

MOV A,#'/'

LCALL WRITE_DATA

MOV R1,#2CH ; DATE

MOV A,@R1

LCALL WRITE_BCD

MOV A,#'/'

LCALL WRITE_DATA

MOV R1,#2EH ; YEAR

MOV A,@R1

LCALL WRITE_BCD

MOV A,#09H ; TAB

LCALL WRITE_DATA

MOV DPTR,#TEXT2 ; TIME:

LCALL WRITE_TEXT

MOV R1,#2AH ; HOURS

MOV A,@R1

LCALL WRITE_BCD

MOV A,#3AH ; COLON

LCALL WRITE_DATA

MOV R1,#29H ; MINUTES

MOV A,@R1

LCALL WRITE_BCD

MOV A,#3AH ; COLON

LCALL WRITE_DATA

MOV R1,#28H ; SECONDS

MOV A,@R1

LCALL WRITE_BCD

RET

;-----------------------------------------------------------------------

; THIS SUB SETS THE OSCILLATOR ACCORDING TO THE OSC BIT

;-----------------------------------------------------------------------

OSC_CONTROL:

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 00H ON DS1307

LCALL SEND_BYTE

MOV A,#00H

LCALL SEND_BYTE

SETB LASTREAD ; SET LAST READ FOR SINGLE READ

LCALL SEND_STOP ; SEND STOP CONDITION

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307R ; SEND READ COMMAND TO DS1307

LCALL SEND_BYTE

LCALL READ_BYTE ; READ SECONDS REGISTER

CLR ACC.7 ; TURN OSC ON

JNB OSC,OSC_SET

SETB ACC.7 ; TURN OSC OFF IF OSC BIT IS SET IN

OSC_SET: ; SECONDS REGISTER

PUSH ACC ; SAVE SECONDS DATA ON STACK

LCALL SEND_STOP ; SEND STOP CONDITION

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 00H ON DS1307

LCALL SEND_BYTE

MOV A,#00H

LCALL SEND_BYTE

POP ACC ; SEND SECONDS REGISTER TO CONTROL

LCALL SEND_BYTE ; OSCILLATOR ON DS1307

LCALL SEND_STOP

RET

;-----------------------------------------------------------------------

; THIS SUB CONTROLS THE SQW OUTPUT 1HZ

;-----------------------------------------------------------------------

SQW_CONTROL_1HZ:

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 07H ON DS1307

LCALL SEND_BYTE

MOV A,#07H

LCALL SEND_BYTE

MOV A,#90H ; SQW/OUT ON AT 1HZ

JNB SQW,SQW_SET ; JUMP IF SQW BIT IS ACTIVE

MOV A,#80H ; TURN SQW/OUT OFF - OFF HIGH

SQW_SET:

LCALL SEND_BYTE

LCALL SEND_STOP

RET

;-----------------------------------------------------------------------

; THIS SUB CONTROLS THE SQW OUTPUT 4KHZ

;-----------------------------------------------------------------------

SQW_CONTROL_4KHZ:

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 07H ON DS1307

LCALL SEND_BYTE

MOV A,#07H

LCALL SEND_BYTE

MOV A,#91H ; SQW/OUT ON AT 1HZ

JNB SQW,SQW_SET1 ; JUMP IF SQW BIT IS ACTIVE

MOV A,#80H ; TURN SQW/OUT OFF - OFF HIGH

SQW_SET1:

LCALL SEND_BYTE

LCALL SEND_STOP

RET

;-----------------------------------------------------------------------

; THIS SUB CONTROLS THE SQW OUTPUT 8KHZ

;-----------------------------------------------------------------------

SQW_CONTROL_8KHZ:

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 07H ON DS1307

LCALL SEND_BYTE

MOV A,#07H

LCALL SEND_BYTE

MOV A,#92H ; SQW/OUT ON AT 1HZ

JNB SQW,SQW_SET2 ; JUMP IF SQW BIT IS ACTIVE

MOV A,#80H ; TURN SQW/OUT OFF - OFF HIGH

SQW_SET2:

LCALL SEND_BYTE

LCALL SEND_STOP

RET

;-----------------------------------------------------------------------

; THIS SUB CONTROLS THE SQW OUTPUT 32KHZ

;-----------------------------------------------------------------------

SQW_CONTROL_32KHZ:

LCALL SEND_START ; SEND START CONDITION

MOV A,#DS1307W ; SET POINTER TO REG 07H ON DS1307

LCALL SEND_BYTE

MOV A,#07H

LCALL SEND_BYTE

MOV A,#93H ; SQW/OUT ON AT 1HZ

JNB SQW,SQW_SET3 ; JUMP IF SQW BIT IS ACTIVE

MOV A,#80H ; TURN SQW/OUT OFF - OFF HIGH

SQW_SET3:

LCALL SEND_BYTE

LCALL SEND_STOP

RET

;-----------------------------------------------------------------------

; THIS SUB IS A SCOPE TRIGGER BIT

;-----------------------------------------------------------------------

TRIGGER:

CLR TRIG

SETB TRIG

LCALL DELAY_4

CLR TRIG

RET

;-----------------------------------------------------------------------

; THIS SUB READS DATA FROM THE SCREEN AND CONVERTS IT TO BCD FORM

; DATA SHOULD BE HEX DIGITS: 1,2,3...9,A,B,C,D,E,F

;-----------------------------------------------------------------------

READ_BCD:

MOV R0,#0 ; CLEAR R0

BCD_LOOP:

LCALL READ_DATA ; READ BYTE FROM KEYBOARD

LCALL WRITE_DATA ; WRITE BYTE BACK TO SCREEN

CJNE A, #0DH, BCD ; CHECK FOR CR

MOV A,R0 ; MOVE R0 TO ACC AND RETURN

RET

BCD:

ADD A,#-30H ; BEGIN TO CONVERT TO ACTUAL VALUE

JNB ACC.4,DIGIT ; JUMP IF NOT A-F

ADD A,#-07H ; IF A-F SUBTRACT 7

DIGIT:

ANL A,#0FH ; ENSURE BITS 4-7 ARE CLEARED

ANL 0,#0FH ; ENSURE BITS 4-7 ARE CLEARED

XCH A,R0 ; EXCHANGE R0 AND ACC

SWAP A ; NIBBLE SWAP ACC

ORL A,R0 ; INSERT BITS 0-3 OF R0 INTO ACC

MOV R0,A ; MOVE ACC INTO R0

SJMP BCD_LOOP ; LOOP UNTIL CR ENCOUNTERED

;-----------------------------------------------------------------------

; THIS SUB WRITES THE BYTE TO THE SCREEN

;-----------------------------------------------------------------------

WRITE_BCD:

PUSH ACC ; SAVE ACC ON STACK

SWAP A ; NIBBLE SWAP ACC

ANL A,#0FH ; CLEAR BITS 4-7 OF ACC

ADD A,#07H ; ADD 7 TO ACC TO CONVERT TO ASCII HEX

JNB ACC.4,LESSNINE ; CHECK TO SEE IF LESS THAN NINE 0-8

CJNE A,#10H,NOTNINE ; JUMP IS GREATER THAN NINE A-F

LESSNINE:

ADD A,#-07H ; SUBTRACT 7 FOR 0-9

NOTNINE:

ADD A,#30H ; ADD 30 TO CONVERT TO ASCII EQUIVALENT

LCALL WRITE_DATA ; WRITE BYTE TO SCREEN

POP ACC ; RECALL ACC FROM STACK

ANL A,#0FH ; PERFORM CONVERSION ON OTHER HALF OF BYTE

ADD A,#07H

JNB ACC.4,NINE2

CJNE A,#10H,NOTNINE2

NINE2:

ADD A,#-07H

NOTNINE2:

ADD A,#30H

LCALL WRITE_DATA

RET

;-----------------------------------------------------------------------

READ_DATA:

JNB RI,READ_DATA ; LOOP WHILE RI BIT IS LOW

CLR RI ;

MOV A,SBUF ; GET DATA BYTE FROM SERIAL BUFFER

RET

;-----------------------------------------------------------------------

WRITE_DATA:

JNB TI,WRITE_DATA ; LOOP WHILE TI BIT IS LOW

CLR TI ;

MOV SBUF,A ; SEND DATA BYTE TO SERIAL

; BUFFER

RET

;-----------------------------------------------------------------------

WRITE_TEXT:

PUSH ACC ; SAVE ACC BYTE ON STACK

WT1:

CLR A ; CLEAR ACC

MOVC A,@A+DPTR ; MOVE FIRST BYTE OF STRING

; TO ACC

INC DPTR ; INC DATA POINTER

CJNE A,#0,WT2 ; CHECK FOR STRING

; TERMINATOR - 0

POP ACC ; RESTORE ACC

RET ; RETURN WHEN STRING IS SENT

WT2:

LCALL WRITE_DATA ; SEND BYTE OF STRING OVER SERIAL PORT

SJMP WT1

;-----------------------------------------------------------------------

; TEXT STRINGS USED FOR USER INTERFACE OVER SERIAL PORT

;-----------------------------------------------------------------------

YEAR:

DB CR,LF,'YEAR (0 - 99) : ',0

MONTH:

DB CR,LF,'MONTH (1 - 12) : ',0

DAY:

DB CR,LF,'DAY OF MONTH : ',0

DAYW:

DB CR,LF,'DAY OF WEEK : ',0

HOUR:

DB CR,LF,'HOUR (0 - 23) : ',0

MINUTE:

DB CR,LF,'MINUTE (0 - 59) : ',0

SECOND:

DB CR,LF,'SECOND (0 - 59) : ',0

TRIER:

DB CR,LF,'PRESS ANY KEY TO SET THIS TIME ',CR,LF,0

TEXT0:

DB CR,LF,'******* DALLAS SEMICONDUCTOR ******* '

DB CR,LF,' DS1307 TEST PROGRAM ',CR,LF

DB CR,LF,'PLEASE CHOOSE AN OPTION TO CONTINUE '

DB CR,LF,'------------------------------------ '

DB CR,LF,'A. SET TIME(MANUAL) B. SET RAM '

DB CR,LF,'C. READ DATE/TIME D. READ RAM '

DB CR,LF,'E. OSC ON F. OSC OFF '

DB CR,LF

DB CR,LF,'G. SQW/OUT ON-1HZ H. SQW/OUT ON-4KHZ'

DB CR,LF,'I. SQW/OUT ON-8KHZ J. SQW/OUT ON-32KHZ'

DB CR,LF

DB CR,LF,'K. SQW/OUT OFF'

DB CR,LF,'L. WRITE RAM UNIQUE PATTERN '

DB CR,LF,'ESC. TO QUIT ',0

TEXT1:

DB CR,'DATE: ',0

TEXT2:

DB 'TIME: ',0

TEXT3:

DB CR,LF,0

TEXT4:

DB CR,LF,'PRESS ANY KEY TO RETURN'

DB CR,LF,0

TEXT5:

DB CR,LF,'ENTER THE BYTE VALUE WHICH WILL FILL THE RAM'

DB CR,LF,0

TEXT6:

DB CR,LF,'RAM RAM'

DB CR,LF,'ADDR DATA'

DB CR,LF,'-----------------------------'

DB CR,LF,0

;******************************************

;**** END OF PROGRAM ************

;******************************************

END

Vehicle tracking system using GPS and GSM modem

2012-05-17T12:08:00.004+05:30

Abstract:
In this Project it is proposed to design an embedded system which is used for tracking and positioning of any vehicle by using Global Positioning System (GPS) and Global system for mobile communication (GSM).

In this project AT89S52 microcontroller is used for interfacing to various hardware peripherals. The current design is an embedded application, which will continuously monitor a moving Vehicle and report the status of the Vehicle on demand. For doing so an AT89S52 microcontroller is interfaced serially to a GSM Modem and GPS Receiver. A GSM modem is used to send the position (Latitude and Longitude) of the vehicle from a remote place. The GPS modem will continuously give the data i.e. the latitude and longitude indicating the position of the vehicle. The GPS modem gives many parameters as the output, but only the NMEA data coming out is read and displayed on to the LCD. The same data is sent to the mobile at the other end from where the position of the vehicle is demanded. An EEPROM is used to store the mobile number.

The hardware interfaces to microcontroller are LCD display, GSM modem and GPS Receiver. The design uses RS-232 protocol for serial communication between the modems and the microcontroller. A serial driver IC is used for converting TTL voltage levels to RS-232 voltage levels.

When the request by user is sent to the number at the modem, the system automatically sends a return reply to that mobile indicating the position of the vehicle in terms of latitude and longitude.

BLOCK DIAGRAM:

Circuit Diagram

Circuit Diagram:

The project is vehicle positioning and navigation system we can locate the vehicle around the globe with 8052 micro controller, GPS receiver, GSM modem, MAX 232, EEPROM. Microcontroller used is AT89S52. The code is written in the internal memory of Microcontroller i.e. ROM. With help of instruction set it processes the instructions and it acts as interface between GSM and GPS with help of serial communication of 8052. GPS always transmits the data and GSM transmits and receive the data.

GPS pin TX is connected to microcontroller via MAX232. GSM pins TX and RX are connected to microcontroller serial ports.

Microcontroller communicates with the help of serial communication. First it takes the data from the GPS receiver and then sends the information to the owner in the form of SMS with help of GSM modem.

GPS receiver works on 9600 baud rate is used to receive the data from space Segment (from Satellites), the GPS values of different Satellites are sent to microcontroller AT89S52, where these are processed and forwarded to GSM. At the time of processing GPS receives only $GPRMC values only. From these values microcontroller takes only latitude and longitude values excluding time, altitude, name of the satellite, authentication etc. E.g. LAT: 1728:2470 LOG: 7843.3089 GSM modem with a baud rate 57600.GSM is a Global system for mobile communication in this project it acts as a SMS Receiver and SMS sender. EEPROM is an Electrically Erasable read only memory which stores is used to store the mobile number.

The power is supplied to components like GSM, GPS and Micro control circuitry using a 12V/3.2A battery .GSM requires 12v,GPS and microcontroller requires 5v .with the help of regulators we regulate the power between three components.

Operating procedure:

To store a Number into the kit

Place a jumper at the pin no 32 “Store Number” as shown in the circuit diagram
Switch on the kit
Wait until you see “Waiting for Call” on the LCD display
Now call from the mobile number from which you need to store the number
Wait until you see “Number stored..” on the LCD
Now remove the Jumper.

Normal Operation

Switch on the kit and wait until you see the Latitude and longitude on the display.
Now give a call from any mobile
The kit will send the location and UTC time to the number stored in its memory.
For emergency the user can press the Button to send the Location to the number stored.
For photos of this project check this link

GSM based Automatic Meter Reading

2012-05-17T11:48:00.000+05:30

Abstarct:
GSM based Automatic meter reading, or AMR, is the technology of automatically collecting data from energy meter and transferring that data to a central database for billing and/or analyzing. The Transmitter is connected to the meter and it counts the pulses from it and displays it over the LCD display. It also transmit the data over RF to the PC. At the receiver end the data is received by an receiver module and the PC application will display it over the PC.

An GSM modem is also connected to the kit so that anybody can call to the number and get back the Meter readings as SMS. The meter reading can be obtained at zero cost. Since the microcontroller will get the mobile number and disconnect the call so the user wont get any charge for the call. Later the microcontroller will send back the meter readings to the called number as SMS.

Main Circuit Diagram:

Receiver

PC Screenshot:

Operating Procedure:

Switch on the kit
Wait until you see the Meter readings on the display
Give a call to the number
You will get the meter readings as SMS

Embedded system project titles

2012-05-17T11:04:00.003+05:30

1. Zigbee Based Hospital Automation with online graph and WAP
2. Infant Incubator Parameter Sensing & Monitoring through ZIGBEE Wireless
3. Eye ball Sensor for automatic wheel chair movement for paralysed patients
4. Automated Environmental Friendly Vechicle System
5. Home appliances control using voice Dictation
6. Pc based Wireless Weather monitoring System
7. Embedded System Based Interlocking Sytsem For Chemical And Pharmacheutical Industries
8. Wireless Roaming Web Cam
9. Voice Controlled Wireless Multitasking Rover
10. SALVO RTOS Based Data Acquisition System and control with PC Interface
11. SUN SAIL - Tracking Elliptical Path Of The Sun
12. Home/Industrial Automation using GSM With Voice Feedback.
13. Embedded PIC MC based_Electronic Trivector Meter
14. Embedded Pic Microcontroller Based Power Multimeter
15. Control of substation equipments thro mobile phone.
16. Embedded Pic Microcontroller Based Motor Protection System
17. Energy Management System For Pulse Output Meters
18. IVRS Based Home Automation With Immediate Voice Feedback
19. Voice Controlled Wheel Chair Robot for Physically challenged.
20. Micro controller based Antilock Braking System using Proximity Sensors
21. PCB Drilling Machine using Cartesian bot
22. Programmable Grass Shredding Robot
23. Automatic Valet Parking System using conveyors
24. Programmable Surface Cleaning Robot using Blowers
25. Embedded System Based Automatic Furnace Control For Improvement Of Hardness On Materials
26. Interactive Telemarketing Device For Advertisement Agencies With Human Approach
27. Single Phase to 3 Phase Converter For Driving 3 Phase Motor using Single Phase
28. Temperature And Humidity Measurement System for Agricultural Applications
29. Embedded System based Automatic Furnace control for improvement of Hardness on materials.
30. Embedded System controlled Electroplating System
31. Embedded System based Transformer Oil Testing Machine.
32. Blue tooth Enabled Home/Industrial Automation
33. IVRS Based Electronic Tele-voting System
34. IVRS Based Control Of Three Axis Robot With Voice Feed Back
35. Embedded System based Cockpit White box automation
36. Energy Efficient Target Coverage in Wireless Sensor Networks
37. Contact less Measurement Of Emission Of Automobiles
38. Design Of Digital Cryogenic Temperature Controller
39. Automated Vertical Car Parking System
40. Remotely Activated Acoustic Warning System (RAAWS)
41. Biometric Finger Print Identification with PIC Based Access Control System
42. Biometric Finger Print Identification with PIC Based Time Recorder with Weigand Output
43. Biometric Finger Print Identification with PIC Based Bank and Locker Security system
44. Biometric Finger Print Identification with PIC Based Vehicle Access System
45. Biometric Fingerprint Based Guard Alert Monitoring system with PC interface
46. RFID Based Guard patrolling system with Handheld Device
47. IRIS Recognition system in Authenticating Highly Secured Data.
48. IRIS Scanner Using Access control Monitoring system
49. Embedded Micro controller Based Nomad Robots for exploration Application
50. Embedded Micro controller Based Robots for weather forecasting.
51. Vehicle Accessing using Authentication
52. Non-Contact Smart Card Reader Based Campus Management system.
53. Web/wap based system for remote monitoring patients with data mining support.
54. Remote Monitoring and Control using Mobile phones
55. Secured Postal Data Communication using RFID and E-POST
56. Distributed Multi area Power systems load flow monitoring
57. Smart Card based Attendance monitoring with Multi-Door output.
58. Secure Transmission of Sensitive data using Multiple channels
59. Micro controller Based Standalone Temperature Measurement System.
60. Micro controller Based Ultrasonic Pulse Detector.
61. Pc Based Flow Control And Level Measurement In Petrol Bunks.
62. Pc As A Pid Controller.
63. Vector Controlled Device For Energy Saving Air Conditioning System.
64. Fuzzy Logic Based Differential Relay For Power Transformer Protection.
65. Electric Power Generation using Footstep Method.
66. Embedded Micro controller based Grid Synchronization.
67. Energy Management Control System with WAP
68. Home Automation Using X-10 Protocol.
69. Bi Directional VF Control of Single Phase AC Motors.
70. Frequency Actuated Load Shedding with substation monitoring
71. Management of sub-transmission and distribution system in power systems
72. Mobile - Half Bridge Configuration Based High Voltage Generation of 10KVA_1KHZ
73. Vector Controlled Drive for Energy Saving in Air Conditioning system
74. High Performance AC Supply with Low Harmonic Distortion for multiphase AC Machines.
75. Enhancement of power system performance using STATCOM
76. Management of sub-transmission and distribution system in power systems.
77. Remote data monitoring using WAP Information Gateway
78. Embedded system based highway monitoring system and control
79. Automatic Anesthesia controller with respiratory system using Heart beat Sensor
80. Intelli mobile robot for multispeciality operations
81. prepaid electricity system automation with contact less proximity card & card reader
82. IVRS Based smart home automation with voice feedback.
83. smart solar tracking for optimal power generation
84. Wireless AI Based voice controlled intelli robot for multispeciality operations
85. Network enabled Electronic Digital televoting machine.
86. Speech Recognition based complete Car Security System
87. OFDM Based Wireless Encryption/Decryption of Transfer of Messages.
88. Synchronized DC Defibrillator with PC Interface
89. Stand-alone Synchronized DC Defibrillator with LCD Interface
90. RF Based Wireless Complete Body Scanning System Using WAP
91. RF Based Medi-Kits for Houses with Emergency Dialer.
92. RF Based Wire less Heart Beat Rate Monitoring System
93. Medicare System for Hospital Automation
94. Study and working of Peritoneal Dialysis with Model.
95. IR based human radiation detection online
96. PC based emergency ambulance calling system
97. PC based body temperature measurement and control
98. Automatic anesthesia feeder based on respiratory
99. Automatic anesthesia feeder based on resp temp with temp with model
100. Automatic anesthesia feeder based on HBC with model.
101. Blue tooth Enabled Wireless Communication with Handheld Device.
102. Advanced Sensors Controlled Bank Security System.
103. Home Networking and Security System With Wap
104. Tape less Voice Storage and Retrieval using APR9600.
105. Electro magnetic Proximity Card Reader with Weigand output based Access Control System with Double Level Security.
106. Electro magnetic Proximity Card Reader with Weigand output based Time and Attendance System.
107. Electro magnetic Proximity Card Reader with Weigand output based Security Cards.
108. EMPCR with Weigand output Based Electricity Billing Automation.
109. EMPCR with Weigand output Based Electricity Billing Automation with WAP.
110. Guard Supervisor for Industries.
111. Guard Alert System for Home Security System.
112. Guard Alert System for industries With Patrolling system.
113. Fire Alarming Control panel with Auto dialer to Fire Station.
114. Hardware Design for Pick and Place Robot
115. Fire Fighting Robotics with artificial intelligence
116. Fire Fighting Robotics With AI (Artificial Intelligence) and WAP
117. Cell Phone Controlled Two Axis Robotics with AI.
118. Cell Phone Controlled Three Axis Robotics with AI.
119. Mobile Phone Controlled Alive Human Detector using Robotics
120. Two Axis Stepper Controller / Driver with Opto-Isolation
121. Multi Axis Stepper Controller / Driver with Opto-Isolation
122. Two Axis Robotics With Artificial Intelligence (AI)
123. Three Axis Robotics With Artificial Intelligence (AI)
124. RF Based Wireless Multi Axis Robotics with WAP
125. PLC ?s for bottle filling station with conveyors
126. Automatic Control of Bottle Filling System Using PLC With Conveyor Model.
127. Embedded PIC Micro controller based Safety Road Control With WEB CAM
128. Embedded PIC Micro controller based Controlling of devices through Telephone Lines
129. DAS and Remote Control through Internet
130. Micro controller based system design for Electronics Laboratory
131. Wireless Home Automation System Using Telephone Lines with WAP
132. RF Based Wireless Encryption And Decryption Message Transfer System for Military Applications
133. Encoding and decoding technique for secured data communication
134. On Line Dynamic Code Acquisition For Spread Spectrum Systems
135. Single Photon Quantum Cryptography
136. Pseudo Random Code modulation based Secured Data Communication.
137. Frequency jammer as a life guard
138. Frequency jammer as a life guard with WAP
139. PC based data scanner/ logger for 8 ? channel
140. PC based data scanner/ logger with field programmable channel
141. Intelligent guided vehicle for collision prevention
142. Fuzzy Logic based Collision Prevention for vehicles.
143. Intelligent Application of Fuzzy Logic in Automatic Train Speed Control System.
144. Fuzzy logic based Traffic Control System - A Replacement strategy
145. Embedded controller for traffic controls
146. Automatic control for unmanned railway gate
147. Automatic control for unmanned railway gate with model
148. Automatic control for unmanned railway gate with WAP
149. Solar power for automatic water heating
150. Solar energy for Electrical Applications
151. Tracking Sun?s path for efficient use of Solar Cell with Model
152. Automated car parking system
153. PC based electronic weighing scale with set point
154. Bluetooth Enabled Advanced Data monitoring and control Using Hitech c.
155. Multi-Parameter Measurement System and Control with Graphs
156. WEB-SCADA 157. Multi Channel Voltage Scanner with SCADA
158. Micro controller based Position Control for Stepper Motor
159. Industrial Safety Measures System with Sensors and Web Cam
160. Industrial Safety Measures System with Sensors
161. Industrial Safety Measures System with Sensors with Voice Indication.
162. Attendance Marker System with IRC Reader
163. Attendance Marker System with IRC Reader and Face indicator
164. Categorized Alarm Annunciator using Embedded System
165. Categorized Alarm Annunciator using Embedded System with controls
166. Categorized Alarm Annunciator with Voice using Embedded System with controls
167. Micro controller based Boiler Management System
168. Priority Indicators in Alarm Annunciators
169. PC Based Programmable Temperature Controller for Furnaces
170. PC Based Programmable Temperature Controller for Cement Plant
171. 8 Channel Temp. Measurement System/Control with True Graphs
172. 8 Channel Temp. Measurement System with True Graphs
173. 8 Channel Temp. Measurement System with True Graphs with Voice indication
174. 8 Channel Multiset point Temperature controller with Different Time Period
175. Multichannel Missing Event Detector
176. Multichannel Missing Event Detector with Voice Indication
177. Battery Voltage and Current Monitoring for 8 Batteries
178. Master / Slave Control System for Process Industries
179. Embedded System based POSI-CAST controller for Dc-Dc Buck Convertor.
180. Electrical Station Variables Reader/Controller with True Graph and SCADA
181. Electrical Station Variable Reader/Controller with True Graph
182. Remote On/Off Controller for AC Motors with Parameter Monitoring
183. Remote Switching System for home appliances
184. Power Sharing of Transformers with WAP
185. Power Sharing of Transformers with auto protection
186. Computer Keyboard as a dual controller for switching Electrical devices
187. Dual control of Electrical devices through Computer Keyboard and H/W
188. Centralized Powerhouse Automation using WAP.
189. Slip Ring Induction motor Drive with slip Recovery using IGBT
190. DC motor Starter using MOSFET
191. Microcontroller Based Oil Temp/IND/CON
192. 3 Phase AC Motor using IGBT
193. Two / Four Quadrent chopper in Indian Military.
194. Ultrasonic Range Finder
195. AC Power line Monitoring motor generator application
196. Speed Control of AC Motor0
197. Speed Control of DC Motor with Field and Armature Control
198. DC Drive using IGBT
199. AC Drive using IGBT
200. Maximum Demand Indicator / Controller for Industries
201. Power Factor Correction Using Multiple Capacitor Banks
202. Electricity Billing Automation
203. Prepaid Electricity Billing Automation
204. Digital Tri Vector Meter
205. Multiple starter with overload protection
206. Multiple starter with overload protection with AI
207. Multiple starter with overload protection with WAP
208. Digital Timer with Thumbwheel setting with On and Off delay type
209. Digital Counter using Proximity Sensor
210. Digital Energy meter using Embedded Controller
211. Digital Energy meter with voice annunciation
212. DC Driver using SCR
213. Digital RPM Indicator using Proximity or Magnetic Pick up
214. Digital Frequency indicator
215. Digital Voltmeter using Embedded System
216. Digital Ammeter using Embedded System
217. Cyclic Timer using Embedded system
218. Remote Digital RPM Indicator using Proximity or Magnetic Pick up with SCADA
219. Remote Frequency indicator with SCADA
220. Length counter using Embedded system
221. Micro controller based access control system
222. Pc based data scanner/ logger for 8 ? channel
223. Pc based data scanner/ logger with field programmable channel
224. Embedded controller for traffic controls
225. High Pressure hose Test Rig for Brake line Manufacturing Industries
226. Embedded PIC Micro controller based Petrol Bunk Automation
227. Speed Control of an Electrical DC Vehicle
228. Fault Tolerant Neuro Controlled Level Processing panel
229. Embedded controller for non linear partially interacting process (NLPIP)
230. Power Distribution Management System using WAP
231. Virtual instrumentation for temperature controlled loop 232. Pc based attendance cum visitor management system
233. Multi Channel Voltage Scanner with SCADA
234. Micro controller based Position Control for Stepper Motor
235. PC Based Programmable Temperature Controller for Furnaces
236. PC Based Programmable Temperature Controller for Cement Plant.
237. Micro controller Based Multichannel PID Controller for temperature
238. Micro controller based Dedicated PID Controller for Temperature
239. PC Based Pollution Tester For Vehicles with WEB CAM Interface
240. PC Based Pollution Tester For Vehicles with CO Analyzer

Musical Tone library for 8051 microcontroller

2012-03-31T11:11:00.001+05:30

Here is another plug and play library for musical tone generation using your 8051 microcontroller. The basic idea behind melody is to produce the correct musical note note.

Theory:

There are seven pitch classes which are represented by first seven letters of Latin alphabets (A, B, C, D, E, F and G). A musical note is represented by Pitch class and octave level, So according to pitch classes there are basic 7 notes and 8th note is represented with as same pitch class as first but double the frequency. The octave is used to differentiate between two notes and is a representation of frequency ratio of two.

Musical notes start from C0, c0#, D0, D0#,.... the lowest note frequency i.e. for C0 is 16.35Hz (based on center frequency A4, 440Hz). Another major component of musical note is duration. There are total 10 durations which are Quarter, Whole, Half, Eighth, Sixteenth, Thirty Two, Sixtyfour, six, twelve and twenty four. These durations vary depending on tempo (beats per minute) of the music/tone.

In music library we focused on notes from C5 to B6 as they coveres almost all variations for simple tone generation and octave level is produce good sound level on hardware (lower frequency means lower sound, higher the frequency higher the sound).

Implementation:

Generating a particular frequency is nothing but a square wave with desired time period. We can use one of the 8051's timer to generate a particular frequency. Lets say if you want to generate C5 note which has a frequency of 523.25Hz, the time period for C5 will be 1911.132µS. The output square wave with 50% duty cycle will have high and low time of 955.566µS (= 1911.132/2).

Lets say your controller running at 12Mhz oscillator will have one Machine cycle of 1µs. To generate 955.566µs we need 956 (~=955.566/1) machine cycles. We can load timer with a value of 64580 (65536-956) and toggle any I/O pin at that interval will give us the reqired frequency. Now this I/o pin can be connected to a speaker to produce sound for that note.

In the library provided we are using Timer2 in auto reload mode for square wave generation. You can use any timer i.e. timer0 or timer1 in 16bit mode for frequency generation. For your convenience I have provided an excel sheet that will generate timer values for a given crystal oscillator frequency.

The sample program and hex file produces following tones:
1. Adam's Family
2. Looney Toons
3. Flintstones
4. Pink Panther
5. Beethoven Play
6. SaReGaMa (Basic Indian sound 7 tones in forward and reverse order).

to download above sample codes and frequency generators table click here

Addition of two packed BCD numbers entered through keyboard

2012-02-16T14:40:00.002+05:30

Write an 8086 program that adds two packed BCD numbers input from the keyboard and computes and displays the result on the system video monitor
Data should be in the form 64+89= The answer 153 should appear in the next line.

Program:

Mov dx, buffer address

Mov ah,0a

Mov si,dx

Mov byte ptr [si], 8

Int 21

Mov ah,0eh

Mov al,0ah

Int 10 ; BIOS service 0e line feed position cursor

sub byte ptr[si+2], 30h

sub byte ptr[si+3], 30h

sub byte ptr[si+5], 30h

sub byte ptr[si+6], 30h

Mov cl,4

Rol byte ptr [si+3],cl

Rol byte ptr [si+6],cl

Ror word ptr [si+2], cl

Mov al, [si+3]

Add al, [si+6]

Daa

Mov bh,al

Jnc display

Mov al,1

Call display

Mov al,bh

Call display

Int 20

Display Subroutine:

mov bl,al ; Save original number and al,f0 ;Force bits 0-3 low

mov cl,4 ; Four rotates

ror al,cl ; Rotate MSD into LSD

add al,30 ; Convert to ASCII

mov ah,0e ; BIOS video service 0E

int 10 ; Display character

mov al,bl ; Recover original number

and al,0f ; Force bits 4-7 low

add al,30 ; Convert to ASCII

int 10 ; Display character

ret ; Return to calling program

;

;Input buffer begins here

interfacing 7 segment display with 8086 processor

2012-02-15T21:32:00.001+05:30

Statement: Program to interface 8086 microprocessor kit with Seven Segment Display and make any digit to Blink

Description:

In this program we interface 8086 microprocessor with Seven Segment Display and diaplay a digit. To interface with Seven Segment Display,we must be familiar with 8255A PPI, which has three ports which can be used as I/O ports. The ports A, B and C are identified using addresses 19H, 1BH, and 1DH respectively and control register address is 1FH. We use Seven Segment Display structure using the following digit

	Digit	Hexadecimal	Decimal	Binary
8	0 1 2 3 4 5 6 7 8 9	C0 F9 A4 B0 99 92 82 F8 80 90	192 249 164 176 153 146 130 248 128 144	11000000 11111001 10100100 10110000 10011001 10010010 10000010 11111000 10000000 10010000

code:

Source program:

MOV AL,10000000B

OUT PPI_C, AL

STR: MOV AL, 10011001B

OUT PPIA,AL

MOV CX, FFFFH

DEL: NOP

NOP

LOOP DEL

MOV AL, 11111111B

OUT PPIA, AL

MOV CX, FFFFH

DEL1: NOP

NOP

LOOP DEL1

JMP STR

HLT

Traffic light programming in assembly for 8086

2012-02-12T15:44:00.001+05:30

; Traffic ligts test 2 for
; c:\emu8086\devices\Traffic_Lights.exe

; This is just an example of how to set the lights,
; DO NOT RUN AT MAXIMUM SPEED, DO NOT USE REAL CARS.
;)

#start=Traffic_Lights.exe#

name "traffic2"

yellow_and_green equ 0000_0110b
red equ 0000_0001b
yellow_and_red equ 0000_0011b
green equ 0000_0100b

all_red equ 0010_0100_1001b

start:
nop

; 0,1,2

mov ax, green
out 4, ax

mov ax, yellow_and_green
out 4, ax

mov ax,red
out 4, ax

mov ax, yellow_and_red
out 4, ax

; 3,4,5

mov ax, green << 3
out 4, ax

mov ax, yellow_and_green << 3
out 4, ax

mov ax,red << 3
out 4, ax

mov ax, yellow_and_red << 3
out 4, ax

; 6,7,8

mov ax, green << 6
out 4, ax

mov ax, yellow_and_green << 6
out 4, ax

mov ax,red << 6
out 4, ax

mov ax, yellow_and_red << 6
out 4, ax

; 9,A,B

mov ax, green << 9
out 4, ax

mov ax, yellow_and_green << 9
out 4, ax

mov ax,red << 9
out 4, ax

mov ax, yellow_and_red << 9
out 4, ax

; all

mov ax, all_red
out 4, ax

mov ax, all_red << 1 ; all yellow
out 4, ax

mov ax, all_red << 2 ; all green :)
out 4, ax

jmp start

work with MASM

2012-01-22T00:29:00.000+05:30

Here we go with MASM means Macro ASseMbler

download MASM 32 bit here

Installing MASM32

Target OS versions
The MASM32 SDK is designed to install on Windows operating system versions from WIN2000 upwards. It is not designed to install on earlier Win9x systems or Windows ME.

Installation Safety Design
The MASM32 SDK is targeted at experienced programmers who routinely have multiple development environments setup and configured on their development computer.

Safety for the experienced developer is as follows,
(1) The MASM32 SDK does not write any files to the operating system.
(2) The MASM32 SDK is registry safe and writes nothing to the registry.
(3) The MASM32 SDK does not set up any file extensions and does not steal file extensions from existing applications.
(4) The MASM32 SDK does not depend on any other application for its operation.
(5) The MASM32 SDK is free of DLL Hell.
(6) The MASM32 SDK is DEP safe, it runs on a fully DEP enabled computer.

At the end of the installation a choice is offered to set up an icon on the desktop using a simple VBS script, its contents are displayed and you have the option of using it or not. This safety comes at the price that the programmer who wants to use the advanced capacity of the MASM32 SDK must have sufficient technical knowledge to configure their development computer so that the MASM SDK can be installed.

Assumptions Of The Installation
The installation assumes that,
(a) The computer is correctly configured and is completely free on any trojan/rootkit/viral damage or infection.
(b) The installation is being performed with ADMINISTRATIVE RIGHTS that allow software to be installed.
(c) The installation can write files to disk without the process being obstructed or damaged by computer settings or security software.

Secure Origin Of The MASM32 SDK Content
The MASM32 SDK is built in a completely isolated environment from its own source code and is completely free of any trojan/rootkit/viral transmission code. It has been successfully installed on millions of development computers over a period in excess of 10 years and the only problems that have ever occurred come from false positives in downmarket AV software. The contents of the MASM32 SDK are DEP SAFE and were re-written when Microsoft introduced the new security modification to the Portable Executable specifications to protect computers from a variety of stack based exploits.

Common Problems With Inexperienced Users
(1) The computer is infected with either a trojan/root kit or virus and interferes with the installation by obstructing the file write to disk process.
SOLUTION : Either completely repair the operating system installation ensuring it is free from any infection or damage or do a full installation of the operating system to ensure it is working correctly.

(2) The person installing the MASM32 SDK does not have sufficient Administrative rights to install software.
SOLUTION : Change to the Administrative Profile before attempting to install the software.

(3) Anti-virus and/or similar security software obstructs the installation of the MASM32 SDK.
SOLUTION : Configure, change or remove the AV software so that it does not interfere with the installation of the MASM32 SDK.

This has primarily been a problem for inexperienced users who are using free security software downloaded from the internet. While reputable AV and security software vendors produce commercial products that properly understand the Microsoft Portable Executable specifications, much of the BETA level freeware available on the internet does not properly do this and regularly delivers FALSE POSITIVES on software that is completely free of any infection. At a design level this follows from the AV product using a naive dictionary approach coupled with poorly designed heuristic scanning methods. The result when using this style of junk is that the AV software often silently removes programs that it does not understand without advising the user and damages the installation of the software.

There is no solution to this problem from the installation end without interfering with the operating system, something that the MASM32 SDK does not do by design. To successfully install the MASM32 SDK you must have the appropriate Administrative rights and the computer must be clean from viral/trojan infections and be configured to allow an installation to write to disk. Unfortunately vendors of this CRAP are protecting their commercial interests by trying to appear as if their software is protecting your computer where in fact their lack of experience exposes end users to risks of large scale unrecoverable damage.

Securing A Development Computer
While most experienced users already know how to protect a development computer, for the small developer or student/person learning a programming environment there are a number of basic guidelines that help to protect a development computer without strangling it with security restrictions designed to protect non-technical users.

(1) Configure the DSL or similar router so that it uses the internal firewall, enables "Stateful Packet Inspection" (SPI) and "Network Address Translation" (NAT) and do not use any form of tunneling that bypasses the router setup. This is particularly important as it cannot be altered by the operating system so even if the operating system is compromised, the router is not and its security features still work.

(2) Unless you know exactly what you are doing with the firewall in late versions of Windows, disable it completely and install a manual setup firewall that allows you to block specific ports and protocols.

(3) Examine the running services on your computer and TURN OFF those that you don't need. Things like remote management, TAPI, FTP and HTTP servers are rarely ever required by a home developer and by turning OFF services of this type, the vulnerable surface area of the computer is reduced. Do not install the IIS internet server option on a development machine as it is subject to new exploits on a regular basis.

(4) NEVER EVER share the boot partition of a development computer. If you need to transfer data from a development computer to another computer in your LAN, set up a directory on another partition on your development computer that has two (2) subdirectories, "upload" and "download". Set up the directories as shared with read only access to the "download" directory and normal read/write access for the "upload" directory. You are safer if you share nothing and use a shared drive/directory on another computer in your LAN to write data to when needed.

(5) If you must use your development computer to handle email there are a number of steps that reduce your risk.

(a) Install software that reads the available email on the email server you use WITHOUT downloading it. This allows you to check what is there and delete any of the junk you don't want without it ever being on your computer.

(b) If your email software automatically downloads email, TURN THE OPTION OFF, only download email when you choose to do so. Malicious software that is never downloaded onto your computer can never do it any harm.

(c) If you must run AV or similar security software, use proven reliable products. Eset's NOD32 and Kaspersky are professional well written products that can be configured properly. Avoid any form of automatic scanning and only operate the software on a needs basis.

Running Security Risks In A Sandbox
If you know what you are doing and properly secure a development computer you can be free of the virus/anti-virus merry go round and be in full control of your development computer but the weakest point in computer security is you the user, no matter what you installation and configuration may happen to be, if you run something that is dangerous you can damage your computer's operating system installation.

If you must do dangerous things like downloading junk from the internet or email that may contain dangerous attachments, do it in a sandbox, install a Virtual Machine on your computer, set up the browser and email programs you want and if the worst happens, you can just shut it down, replace the virtual hard drive file with a backup and no harm is done.

The Final Solution For Computer Security
Obtain a reliable disk imaging program, Norton Ghost, Acronis True Image and similar and learn how to use it correctly. Make a backup image of your BOOT partition and save that file on another partition on your computer. Software like Acronis has the capacity to create a bootable CD so that you can boot the damaged computer from the CD and restore the disk image file saved on another partition. This approach has two (2) major advantages, it cannot be beaten as it completely overwrites the damaged operating system installation and it usually takes less than five (5) minutes to perform.

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Classification of Instruction set of 8086 with sample programs

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Click on each instruction to read its function,explanation and its sample Program.

DATA TRANSFER INSTRUCTIONS

GENERAL – PURPOSE BYTE OR WORD TRANSFER INSTRUCTIONS	SIMPLE INPUT AND OUTPUT PORT TRANSFER INSTRUCTION	SPECIAL ADDRESS TRANSFER INSTRUCTION	FLAG TRANSFER INSTRUCTIONS
MOV PUSH POP XCHG XLAT/XLATB	IN OUT	LEA LDS LES	LAHF SAHF PUSHF POPF

ARITHMETIC INSTRUCTIONS

ADDITION INSTRUCTIONS	SUBTRACTION INSTRUCTIONS	MULTIPLICATION INSTRUCTIONS	DIVISION INSTRUCTIONS
ADD ADC INC AAA DAA	SUB SBB DEC NEG CMP AAS DAS	MUL IMUL AAM	DIV IDIV AAD CBW CWD

BIT MANIPULATION INSTRUCTIONS

LOGICAL INSTRUCTIONS	SHIFT INSTRUCTIONS	ROTATE INSTRUCTIONS
NOT AND OR XOR TEST	SHL / SAL SHR SAR	ROL ROR RCL RCR

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STRING INSTRUCTIONS

STRING INSTRUCTIONS

REP
REPE / REPZ
REPNE / REPNZ
MOVS / MOVSB / MOVSW
COMPS / COMPSB / COMPSW
SCAS / SCASB / SCASW
LODS / LODSB / LODSW
STOS / STOSB / STOSW

PROGRAM EXECUTION TRANSFER INSTRUCTIONS

UNCONDITIONAL TRANSFER INSTRUCTIONS

CONDITIONAL TRANSFER INSTRUCTIONS

ITERATION CONTROL INSTRUCTIONS

INTERRUPT INSTRUCTIONS

CALL
RET
JMP

JA / JNBE
JAE / JNB
JB / JNAE
JBE / JNA
JC
JE / JZ
JG / JNLE
JGE / JNL
JL / JNGE

JLE / JNG
JNC
JNE / JNZ
JNO
JNP / JPO
JNS
JO

JP / JPE
JS

LOOP
LOOPE / LOOPZ
LOOPNE / LOOPNZ
JCXZ

INT
INTO
IRET

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PROCESS CONTROL INSTRUCTIONS

FLAG SET / CLEAR INSTRUCTIONS	EXTERNAL HARDWARE SYNCHRONIZATION INSTRUCTIONS
STC CLC CMC STD CLD STI CLI	HLT WAIT ESC LOCK NOP

Rotate instructions

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ROTATE INSTRUCTIONS

ROL Instruction - Rotate all bits of operand left, MSB to LSB

ROL instruction rotates the bits in the operand specified by oper1 towards left by the count specified in oper2. ROL moves each bit in the operand to next higher bit position. The higher order bit is moved to lower order position. Last bit rotated is copied into carry flag.

Syntax - ROL destination, count.

Example: ( 1 )

ROL AX, 1 ;Word in AX is moved to left by 1 bit and MSB bit is to LSB, and CF and CF =0 ,BH =10101110
ROL BH, 1 ;Result: CF ,Of =1 , BH = 01011101

Example : ( 2 )
;BX = 01011100 11010011 and CL = 8 bits to rotate
ROL BH, CL ;Rotate BX 8 bits towards left and CF =0, BX =11010011 01011100

ROR Instruction - Rotate all bits of operand right, LSB to MSB

ROR instruction rotates the bits in the operand oper1 to wards right by count specified in op2. The last bit rotated is copied into CF.

Syntax - ROR destination, count

Example:( 1 )

ROR BL, 1 ;Rotate all bits in BL towards right by 1 bit position, LSB bit is moved to MSB and CF has last rotated bit.

Example:( 2 )
;CF =0, BX = 00111011 01110101
ROR BX, 1 ;Rotate all bits of BX of 1 bit position towards right and CF =1, BX = 10011101 10111010

Example ( 3 )

                             ;CF = 0, AL = 10110011,
MOVE CL, 04H           ; Load CL
ROR AL, CL               ;Rotate all bits of AL towards right by 4 bits, CF = 0 ,AL = 00111011

RCL Instruction - Rotate operand around to the left through CF

RCL instruction rotates the bits in the operand specified by oper1 towards left by the count specified in oper2.The operation is circular, the MSB of operand is rotated into a carry flag and the bit in the CF is rotated around into the LSB of operand.

Syntax - RCL destination, source.

Example(1):

CLC                         ;put 0 in CF
RCL AX, 1                ;save higher-order bit of AX in CF
RCL DX, 1                ;save higher-order bit of DX in CF
ADC AX, 0                ; set lower order bit if needed.

Example (2):

RCL DX, 1 ;Word in DX of 1 bit is moved to left, and MSB of word is given to CF and CF to LSB CF=0, BH = 10110011

RCL BH, 1 ;Result : BH =01100110 CF = 1, OF = 1 because MSB changed CF =1,AX =00011111 10101001

MOV CL, 2 ;Load CL for rotating 2 bit position
RCL AX, CL ;Result: CF =0, OF undefined AX = 01111110 10100110

RCR Instruction - Rotate operand around to the right through CF

RCR Instruction - RCR instruction rotates the bits in the operand specified by operand1 towards right by the count specified in operand2.

Syntax - RCR destination, count

Example:(1)

RCR BX, 1 ;Word in BX is rotated by 1 bit towards right and CF will contain MSB bit and LSB contain CF bit .

Example:(2)

;CF = 1, BL = 00111000
RCR BL, 1 ;Result: BL = 10011100, CF =0 OF = 1 because MSB is changed to 1.

shift instrcuctions

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SHIFT INSTRUCTIONS

SAL/SHL Instruction - Shift operand bits left, put zero in LSB(s)

SAL instruction shifts the bits in the operand specified by op1 to its left by the count specified in op2. As a bit is shifted out of LSB position a 0 is kept in LSB position. CF will contain MSB bit.

Syntax - SAL/AHL destination, count

Example:

                                            ;CF = 0, BX = 11100101 11010011
SAL BX, 1                           ;Shift BX register contents by 1 bit position towards left
                                            ;CF = 1, BX = 11001011 1010011

SHR Instruction - Shift operand bits right, put zero in MSB

SHR instruction shifts the bits in op1 to right by the number of times specified by op2 .

Example:( 1 )

SHR BP, 1 ; Shift word in BP by 1 bit position to right and 0 is kept to MSB

Example:( 2 )

MOV CL, 03H ;Load desired number of shifts into CL
SHR BYTE PYR[BX] ;Shift bytes in DS at offset BX and rotate 3 bits to right and keep 3 0’s in MSB

Example:( 3 )

;SI = 10010011 10101101 , CF = 0
SHR SI, 1 ; Result: SI = 01001001 11010110 and CF = 1, OF = 1, SF = 0, ZF = 0

SAR Instruction - Shift operand bits right, new MAB = old MSB

SAR instruction shifts the bits in the operand specified by op1 towards right by count specified in op2.As bit is shifted out a copy of old MSB is taken in MSB. MSB position and LSB is shifted to CF.

Syntax - SAR destination, count.

Example: ( 1 )
                                     ; AL = 00011101 = +29 decimal, CF = 0
SAR AL, 1                     ;Shift signed byte in AL towards right ( divide by 2 )
                                         ;AL = 00001110 = + 14 decimal, CF = 1

Example: ( 2 )
;BH = 11110011 = - 13 decimal, CF = 1
SAR BH, 1 ;Shifted signed byte in BH to right and BH = 11111001 = - 7 decimal, CF = 1.

logical instructions

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LOGICAL INSTRUCTIONS

NOT Instruction - Invert each bit of operand

NOT perform the bitwise complement of operand and stores the result back into operand itself.

Syntax–NOT destination

Example :

NOT BX ;Complement contents of BX register. - DX =F038h
NOT DX ;after the instruction DX = 0FC7h

AND Instruction - AND corresponding bits of two operands

This Performs a bitwise Logical AND of two operands. The result of the operation is stored in the op1 and used to set the flags. AND op1, op2 To perform a bitwise AND of the two operands, each bit of the result is set to 1 if and only if the corresponding bit in both of the operands is 1, otherwise the bit in the result I cleared to 0 .

Example :

AND BH, CL ;AND byte in CL with byte in BH ;result in BH
AND BX,00FFh ;AND word in BX with immediate 00FFH. Mask upper byte, leave lower unchanged

AND CX,[SI] ; AND word at offset [SI] in data segment with word in CX register . Result in CX register and BX = 10110011 01011110

AND BX,00FFh ;Mask out upper 8 bits of BX. ;Result BX = 00000000 01011110 and CF =0 , OF = 0, PF = 0, SF = 0 ,ZF = 0.

OR Instruction - Logically OR corresponding of two operands

OR Instruction - OR instruction perform the bit wise logical OR of two operands .Each bit of the result is cleared to 0 if and only if both corresponding bits in each operand are 0, other wise the bit in the result is set to 1.

Syntax–- OR destination, source.

Examples :

OR AH, CL                         ;CL is OR’ed with AH, result in AH.
                                   ;CX = 00111110 10100101
OR CX,FF00h                     ;OR CX with immediate FF00h result in CX = 11111111 10100101
                                 ;Upper byte are all 1’s lower bytes are unchanged.

XOR Instruction - Exclusive XOR destination, source

XOR Instruction - XOR performs a bit wise logical XOR of the operands specified by op1 and op2. The result of the operand is stored in op1 and is used to set the flag.

Syntax–- XOR destination, source.

Example : ( Numerical )
; BX = 00111101 01101001 and CX = 00000000 11111111
XOR BX, CX ;Exclusive OR CX with BX and Result BX = 00111101 10010110

TEST Instruction – AND operand to update flags

TEST Instruction - This instruction ANDs the contents of a source byte or word with the contents of specified destination word. Flags are updated but neither operand is changed . TEST instruction is often used to set flags before a condition jump instruction

Examples:

TEST AL, BH ;AND BH with AL. no result is stored . Update PF, SF, ZF TEST CX, 0001H ;AND CX with immediate number
;no result is stored, Update PF,SF

Example :

                            ;AL = 01010001
TEST Al, 80H                    ;AND immediate 80H with AL to test f MSB of AL is 1 or 0
                                     ;ZF = 1 if MSB of AL = 0 and AL = 01010001 (unchanged),PF = 0 , SF = 0,
                                   ;ZF = 1 because ANDing produced is 00

DIVISION INSTRUCTIONS

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DIVISION INSTRUCTIONS

DIV Instruction - Unsigned divide-Div source

When a double word is divided by a word, the most significant word of the double word must be in DX and the least significant word of the double word must be in AX. After the division AX will contain the 16 –bit result (quotient ) and DX will contain a 16 bit remainder. Again , if an attempt is made to divide by zero or quotient is too large to fit in AX ( greater than FFFFH ) the 8086 will do a type of 0 interrupt .

Example:

DIV CX ; (Quotient) AX= (DX:AX)/CX
; (Reminder) DX=(DX:AX)%CX

For DIV the dividend must always be in AX or DX and AX, but the source of the divisor can be a register or a memory location specified by one of the 24 addressing modes.
If you want to divide a byte by a byte, you must first put the dividend byte in AL and fill AH with all 0’s . The SUB AH,AH instruction is a quick way to do. If you want to divide a word by a word, put the dividend word in AX and fill DX with all 0’s. The SUB DX,DX instruction does this quickly.

Example:

                                           ; AX = 37D7H = 14, 295 decimal and BH = 97H = 151 decimal
DIV BH                                 ;AX / BH
                                           ; AX = Quotient = 5EH = 94 decimal and AH = Remainder = 65H = 101

decimal.

IDIV Instruction - Divide by signed byte or word IDIV source

This instruction is used to divide a signed word by a signed byte or to divide a signed double word by a signed word. If source is a byte value, AX is divided by register and the quotient is stored in AL and the remainder in AH. If source is a word value, DX:AX is divided by register,and the quotient is stored in AL and the remainder in DX.

Example:

IDIV BL ;Signed word in AX is divided by signed byte in BL

AAD Instruction - ASCII adjust before Division

ADD converts unpacked BCD digits in the AH and AL register into a single binary number in the AX register in preparation for a division operation. Before executing AAD, place the Most significant BCD digit in the AH register and Last significant in the AL register. When AAD is executed, the two BCD digits are combined into a single binary number by setting AL=(AH*10)+AL and clearing AH to 0.

Example:

MOV AX,0205h ;The unpacked BCD number 25
AAD ;After AAD , AH=0 and AL=19h (25).

After the division AL will then contain the unpacked BCD quotient and AH will contain the unpacked BCD remainder.

Example:

                                         ;AX=0607 unpacked BCD for 67 decimal CH=09H.
AAD                                 ;Adjust to binary before division AX=0043 = 43H =67 decimal.
DIV CH                             ;Divide AX by unpacked BCD in CH, AL = quotient = 07 unpacked BCD, AH = remainder = 04 unpacked BCD

CBW Instruction - Convert signed Byte to signed word

CBW converts the signed value in the AL register into an equivalent 16 bit signed value in the AX register by duplicating the sign bit to the left. This instruction copies the sign of a byte in AL to all the bits in AH. AH is then said to be the sign extension of AL.

Example:

                                        ; AX = 00000000 10011011 = - 155 decimal
CBW                               ; Convert signed byte in AL to signed word in AX.
                                      ; Result in AX = 11111111 10011011 and = - 155 decimal

CWD Instruction - Convert Signed Word to - Signed Double word

CWD converts the 16 bit signed value in the AX register into an equivalent 32 bit signed value in DX: AX register pair by duplicating the sign bit to the left.
The CWD instruction sets all the bits in the DX register to the same sign bit of the AX register. The effect is to create a 32- bit signed result that has same integer value as the original 16 bit operand.

Example:

Assume AX contains C435h. If the CWD instruction is executed, DX will contain FFFFh since bit 15 (MSB) of AX was 1. Both the original value of AX (C435h) and resulting value of DX : AX (FFFFC435h) represents the same signed number.

Example:

                                   ;DX = 00000000 00000000 and AX = 11110000 11000111 = - 3897 decimal
CWD                            ;Convert signed word in AX to signed double word in DX:AX
                                   ;Result DX = 11111111 11111111 and AX = 11110000 11000111 = -3897 decimal.

multiplication instructions

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MULTIPLICATION INSTRUCTIONS

MUL Instruction - Multiply unsigned bytes or words-MUL source

MUL Instruction - This instruction multiplies an unsigned multiplication of the accumulator by the operand specified by op. The size of op may be a register or memory operand .

Syntax: MUL op

Example:

                                             ;AL = 21h (33 decimal),BL = A1h(161 decimal )
MUL BL                                 ;AX =14C1h (5313 decimal) since AH≠0, CF and OF will set to 1.
MUL BH                              ; AL times BH, result in AX
MUL CX                                  ;AX times CX, result high word in DX,low word in AX.

IMUL Instruction - Multiply signed number-IMUL source

This instruction performs a signed multiplication.There are two types of syntax for this instruction. They are:

IMUL op ;In this form the accumulator is the multiplicand and op is the multiplier. op may be a register or a memory operand.
IMUL op1, op2 ;In this form op1 is always be a register operand and op2 may be a register or a memory operand.

Example:

IMUL BH ;Signed byte in AL times multiplied by signed byte in BH and result in AX .

Example:

                                          ; 69 * 14
                                          ; AL = 01000101 = 69 decimal
                                          ; BL = 00001110 = 14 decimal
IMUL BL                               ;AX = 03C6H = + 966 decimal ,MSB = 0 because positive result , - 28 * 59
                                          ; AL = 11100100 = - 28 decimal ,BL = 00001110 = 14 decimal
IMUL BL                               ;AX = F98Ch = - 1652 decimal, MSB = 1 because negative result

AAM Instruction - ASCII adjust after Multiplication

AAM Instruction - AAM converts the result of the multiplication of two valid unpacked BCD digits into a valid 2-digit unpacked BCD number and takes AX as an implicit operand. To give a valid result the digits that have been multiplied must be in the range of 0 – 9 and the result should have been placed in the AX register. Because both operands of multiply are required to be 9 or less, the result must be less than 81 and thus is completely contained in AL. AAM unpacks the result by dividing AX by 10, placing the quotient (MSD) in AH and the remainder (LSD) in AL.

Example:

MOV AL, 5
MOV BL, 7
MUL BL ;Multiply AL by BL , result in AX
AAM ;After AAM, AX =0305h (BCD 35)

subtarction (arithmetic instruction set)

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SUBTRACTION INSTRUCTIONS

SUB Instruction - Subtract two numbers

These instructions subtract the source number from destination number destination and put the result in the specified destination. The source and destination must be of same type , means they must be a byte location or a word location.

SBB Instruction - Subtract with borrow SBB destination, source

SBB instruction subtracts source from destination, and then subtracts 1 from source if CF flag is set and result is stored destination and it is used to set the flag.

ie.,destination = destination -(source + CF)

Example:

SUB CX, BX                                 ;CX – BX . Result in CX
SUBB CH, AL                               ; Subtract contents of AL and contents CF from contents of CH .
;Result in CH
SUBB AX, 3427H                      ;Subtract immediate number from AX

Example:

- Subtracting unsigned number
                                               ; CL = 10011100 = 156 decimal BH = 00110111 = 55 decimal
SUB CL, BH                               ; CL = 01100101 = 101 decimal CF, AF, SF, ZF = 0, OF, PF = 1
- Subtracting signed number
                                               ; CL = 00101110 = + 46 decimal BH = 01001010= + 74 decimal
SUB CL, BH                               ;CL = 11100100 = - 28 decimal,CF = 1, AF, ZF =0,SF = 1 result negative

DEC Instruction - Decrement destination register or memory DEC destination.

DEC instruction subtracts one from the operand and sets the flag according to the result. DEC instruction is treated as an unsigned binary number.

Example:

                                              ; AX =8000h
DEC AX                                  ;After this instruction AX = 7999h
DEC BL                                    ; Subtract 1 from the contents of BL register

NEG Instruction - From 2’s complement – NEG destination

NEG performs the two’s complement subtraction of the operand from zero and sets the flags according to the result.

;AX = 2CBh
NEG AX ;after executing NEG result AX =FD35h.

Example:

NEG AL ;Replace number in AL with its 2’s complement

NEG BX ;Replace word in BX with its 2’s complement

NEG BYTE PTR[BX] ; Replace byte at offset BX in DS with its 2’s complement

CMP Instruction - Compare byte or word -CMP destination, source.

The CMP instruction compares the destination and source ie.,it subtracts the source from destination.The result is not stored anywhere. It neglects the results, but sets the flags accordingly.This instruction is usually used before a conditional jump instruction.

Example:

MOV AL, 5
MOV BL, 5
CMP AL, BL ; AL = 5, ZF = 1 (so equal!)
RET

AAS Instruction - ASCII Adjust for Subtraction

AAS converts the result of the subtraction of two valid unpacked BCD digits to a single valid BCD number and takes the AL register as an implicit operand. The two operands of the subtraction must have its lower 4 bit contain number in the range from 0 to 9 .The AAS instruction then adjust AL so that it contain a correct BCD digit.

MOV AX,0901H                   ;BCD 91
SUB AL, 9                            ;Minus 9
AAS                                    ; Give AX =0802 h (BCD 82)

Example:( a )
                                         ;AL =0011 1001 =ASCII 9
                                         ;BL=0011 0101 =ASCII 5
SUB AL, BL                    ;(9 - 5) Result : ;AL = 00000100 = BCD 04,CF = 0
AAS                                    ;Result : AL=00000100 =BCD 04 , CF = 0 NO Borrow required

Example:( b )

                                         ;AL = 0011 0101 =ASCII 5
                                         ;BL = 0011 1001 = ASCII 9
SUB AL, BL                        ;( 5 - 9 ) Result : AL = 1111 1100 = – 4 in 2’s complement CF = 1
AAS                                ;Results :AL = 0000 0100 =BCD 04, CF = 1 borrow needed

DAS Instruction - Decimal Adjust after Subtraction

This instruction corrects the result (in AL) of subtraction of two packed BCD values. The flags which modify are AF, CF, PF, SF, ZF

if low nibble of AL > 9 or AF = 1 then:

- AL = AL – 6

- AF = 1

if AL > 9Fh or CF = 1 then:

- AL = AL - 60h

- CF = 1

Example:

MOV AL, 0FFh ; AL = 0FFh (-1)
DAS ; AL = 99h, CF = 1
RET

Arithmetic instructions

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• ADD Instruction - ADD destination, source
These instructions add a number from source to a number from some destination and put the result in the specified destination. The source and destination must be of same type , means they must be a byte location or a word location. If you want to add a byte to a word, you must copy the byte to a word location and fill the upper byte of the word with zeroes before adding.
• ADC Instruction - Add with carry
After performing the addition, the add with carry instruction ADC, adds the status of the carry flag into the result.
EXAMPLE:
ADD AL,74H ;Add immediate number 74H to content of AL
ADC CL,BL ;Add contents of BL plus carry status to contents of CL Results in CL
ADD DX, BX ;Add contents of BX to contents of DX
ADD DX, [SI] ;Add word from memory at offset [SI] in DS to contents of DX
; Addition of Un Signed numbers
ADD CL, BL ;CL = 01110011 =115 decimal + BL = 01001111 = 79 decimal Result in CL = 11000010 = 194 decimal
; Addition of Signed numbers
ADD CL, BL ;CL = 01110011 = + 115 decimal + BL = 01001111 = +79 decimal Result in CL = 11000010 = - 62 decimal
; Incorrect because result is too large to fit in 7 bits.
• INC Instruction - Increment - INC destination
INC instruction adds one to the operand and sets the flag according to the result. INC instruction is treated as an unsigned binary number.
Example:
; AX = 7FFFh
INC AX ;After this instruction AX = 8000h
INC BL ; Add 1 to the contents of BL register
INC CL ; Add 1 to the contents of CX register.
• AAA Instruction - ASCII Adjust after Addition
AAA converts the result of the addition of two valid unpacked BCD digits to a valid 2-digit BCD number and takes the AL register as its implicit operand.
Two operands of the addition must have its lower 4 bits contain a number in the range from 0-9.The AAA instruction then adjust AL so that it contains a correct BCD digit. If the addition produce carry (AF=1), the AH register is incremented and the carry CF and auxiliary carry AF flags are set to 1. If the addition did not produce a decimal carry, CF and AF are cleared to 0 and AH is not altered. In both cases the higher 4 bits of AL are cleared to 0.
AAA will adjust the result of the two ASCII characters that were in the range from 30h (“0”) to 39h(“9”).This is because the lower 4 bits of those character fall in the range of 0-9.The result of addition is not a ASCII character but it is a BCD digit.
Example:
MOV AH,0 ;Clear AH for MSD
MOV AL,6 ;BCD 6 in AL
ADD AL,5 ;Add BCD 5 to digit in AL
AAA ;AH=1, AL=1 representing BCD 11.
• DAA Instruction - Decimal Adjust after Addition
The contents after addition are changed from a binary value to two 4-bit binary coded decimal (BCD) digits. S, Z, AC, P, CY flags are altered to reflect the results of the operation.
If the value of the low-order 4-bits in the accumulator is greater than 9 or if AC flag is set, the instruction adds 6 to the low-order four bits.
If the value of the high-order 4-bits in the accumulator is greater than 9 or if the Carry flag is set, the instruction adds 6 to the high-order four bits.
Example:
MOV AL, 0Fh ; AL = 0Fh (15)
DAA ; AL = 15h
RET

FLAG TRANSFER INSTRUCTIONS

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FLAG TRANSFER INSTRUCTIONS

LAHF Instruction - Load Register AH From Flags

LAHF instruction copies the value of SF, ZF, AF, PF, and CF, into bits of 7, 6, 4, 2, 0 respectively of AH register. This LAHF instruction was provided to make conversion of assembly language programs written for 8080 and 8085 to 8086 easier.

SAHF instruction - Store AH Register into FLAGS

SAHF instruction transfers the bits 0-7 of AH of SF, ZF, AF, PF, and CF, into the Flag register.

PUSHF Instruction - Push flag register on the stack

This instruction decrements the SP by 2 and copies the word in flag register to the memory location pointed to by SP.

POPF Instruction - Pop word from top of stack to flag - register.

This instruction copies a word from the two memory location at the top of the stack to flag register and increments the stack pointer by 2.