Rickey's World of Microcontrollers & Microprocessors : Forum / posts

Re: 8051 Microcontroller LCD Troubleshooting

ExperimenterUK — Sun, 19 Jan 2025 02:30:03 +0530

Are you still having problems ?

8051 Microcontroller LCD Troubleshooting

JaneWill — Fri, 10 Jan 2025 01:37:33 +0530

I'm working on an 8051 microcontroller project, trying to interface an LCD and a keypad for input and output. The problem is that no characters appear on the screen after initialization while the LCD backlight turns on. I’ve checked the wiring and added delays in the code, but it’s still not working. Could this be an issue with the Enable pin timing or the 4-bit data mode setup? What’s the best way to troubleshoot and get the LCD to communicate with the microcontroller?

Re: How can i calculate minimum ISR interval for nuvoton -8051(8bit)?

JaneWill — Thu, 09 Jan 2025 01:14:28 +0530

How does the microcontroller handle interrupt priority if two interrupts occur within a shorter interval than the ISR execution time?

MAX7219 and over clocking

jona — Sun, 04 Aug 2024 13:18:31 +0530

I recently started playing with smd MAX7219 8x8 LED modules. I arrange four horizontal four-in-one modules in a square 32x32 LED matrix, with the five input pins coming off the right end of the top four-in-one module. Now, because I rotated the modules 90 degrees, what were columns become rows. I noticed that the 10uF capacitor is not included on each module, so I added one to each module, a total of 16 caps. I used a 12mHz crystal on my AT89S52 minimum system board.
My program first sets up the control registers, then repeats the following: display a blank screen, then scrolls down a smiley face from the top, pausing when the full face is displayed to blink one of the eyes, followed by the face scrolling down until a blank screen. Repeat.
Two problem types arose. Various 8x8 modules near the end of the chain will either go blank altogether, or only the first row (nee column) displays extra bright. I attribute this behavior to corruption of the shutdown and scan limit control registers, respectively. I confirmed my suspicion by putting a detour in the program that repeats the portions of code that initializes those two registers. That detour is invoked by pulling low an otherwise unused pin on the AT89S52. After invoking that detour the affected modules go back to normal operation.
The other problem type is the middle six LEDs (as if 7Eh were sent to that module) in a row are turned permanently on. They do not scroll. The detour described in the preceding paragraph does not clear up this problem.
A posting at
https://www.edaboard.com/threads/about-at89s52-24pc-crystal-oscillator-frequency.178905/
described using a 48mHz active crystal, so I tried one, with slight modification to the board. I made no changes to the program, and now the two types of problems described above are gone. However, a new problem arose: the display will freeze, and then in a short time continue as if nothing happened. I felt that the AT89S52 was getting warm so I attached a heat sink and a small fan, and that new problem disappeared.
Any insights on why over clocking the AT89S52 with an active crystal would fix the problems?

Re: HC-SR04 displaying random stuff after range 9

ExperimenterUK — Fri, 08 Dec 2023 08:50:58 +0530

We need to see the rest of your code.
Comments to explain what is supposed to happen would be useful.

Re: HC-SR04 displaying random stuff after range 9

bhantadox — Thu, 30 Nov 2023 15:58:41 +0530

Image

Re: HC-SR04 displaying random stuff after range 9

bhantadox — Thu, 30 Nov 2023 15:56:17 +0530

unsigned int get_range(void)
{
long int timer_val;
send_pulse();
while(!INT0); //Waiting until echo pulse is detected
while(INT0); //Waiting until echo pulse changes its state
timer_val=(TH0<<8)+TL0;
lcd_cmd(0x81);
lcd_data_string("output:");
lcd_cmd(0x8a);
if(timer_val<38000)
{
cms=timer_val/59;
if (cms!=0)
{
lcd_data(cms+48);

if(cms<15)
{
P1=0xFF;
}
else

{P1=0X00;}

}
}
else
{
lcd_cmd(0x06);
lcd_data_string("Object out of range");
}
return cms;
}

HC-SR04 displaying random stuff after range 9

bhantadox — Thu, 30 Nov 2023 15:55:28 +0530

Im using 8051, LM016L and HC-SR04 for range finder but after range 9 it starts to display random stuff.

Re: 8051 keypad and LED question

ExperimenterUK — Tue, 19 Sep 2023 07:49:16 +0530

To use this kind of keypad you must "scan" it,
This means setting pins P2.1,P2.2 and P2.3 high then low one after the other.
Your pins do not change, so pressing a key does nothing.

8051 keypad and LED question

fortresmaximus — Wed, 30 Aug 2023 11:53:38 +0530

Hi guys, i am new here.

I need to create project with microcontroller 8051,
in project i want to use KEYPAD-PHONE and 4 LED (for example if i click 1 on keypad - first LED will light up,

Could someone give me a hint what i am doing wrong?

8051/ 8052 Microcontroller Code Site.

Tressie — Thu, 10 Aug 2023 18:30:15 +0530

Just a quick note to let everyone know that my 8051/ 8052 Microcontroller Code distribution website is back online, and has a new home at:

https://green.bug-eyed.monster/

Please feel free to stop by, grab some handy code projects, and leave a comment or two.

It's a new website, with no PR as yet, so helping to popularise the site by linking to it, will help everyone know it's available.

T.

Erasing AT89S52 error

cainho07 — Sun, 16 Jul 2023 06:55:49 +0530

Hello everyone!

I recently bought a brand new AT89S52 and an USBasp programmer for practicing and studying. Took a lot of time to get everything working between drivers and USBasp firmwares until I finally made it but unfortunately, I think I accidentally wrote the lock bits because I didn't check the lock option. Now it says that Mode 3 lock is active with B1 = 1 and B2 = 0. I've hit the erase chip button many times but when I read the lock bits status, it always remain the same. Apparently, the new .hex files are working when I try to write but is there a way to really erase the chip or did I brick it? Thanks in advance!

Re: Automatically sending of SMS via Nokia 3310

jacksonjk — Tue, 11 Oct 2022 12:51:19 +0530

My Nokia phone will not send SMS to short 5-digit numbers. I continually receive the message in red saying "Not sent, tap to try again.". It doesn't matter how many times I tap, and try, the same failure message appears. Where in the settings can I overcome this?

Source: www.smsala.com

Re: microcontroller

liqian — Fri, 07 Aug 2020 09:01:33 +0530

I found the part on here https://www.jotrin.com/product/parts/74HC595, there is detail information about it and I hope it can really help you.

Re: AT89LP2052 connection

ExperimenterUK — Thu, 02 Jul 2020 04:37:57 +0530

PS: I am a new learner thats why my question may sound silly.

Not silly at all.
There are a lot of details experts don't tell you that are really hard to figure out
on your own.

You will need a special header for the AT89LP2052 as it uses registers the 8051 does not have.
The header will also have to written for use in Microc as every compiler has it's own
way of doing things.

For a quick test I think this will work.
Add these 2 lines to the top of the file

#define P1M0 0xc2
#define P1M1 0xc3

and these 2 at the start of main.
P1MO= 0x00;
P1M1= 0x00;

Some P1 pins are used for programming, so I suggest you only
connect a LED to pin 14 ( P1.2)
Also it is safer to add resistors between the LEDs and the chip.
Anything between 47 and 200 ohms should be okay.

To start with, try this program to turn the LEDs on.
That will prove something is working, you can do flashing later.

#include
#define     P1M0 0xc2
#define     P1M1 0xc3

void main()
{
P1MO= 0x00;
P1M1= 0x00;

P1= 0xff
while(1)
{}

}

Re: AT89LP2052 connection

Mirza123 — Wed, 01 Jul 2020 19:35:16 +0530

Thanks for the assistance. I have read the data sheet. if PxM0.y=0 and PxM1.y=0 then it will work as standard 8051MCU. but i want to know how can i make PxM0.y=0 and PxM1.y=0 ? which special function register should be changed? Should i use the same header file( #include)?
PS: I am a new learner thats why my question may sound silly.

Re: AT89LP2052 connection

ExperimenterUK — Wed, 01 Jul 2020 15:42:39 +0530

See section 15 (Ports) of the data sheet.

Attachment

doc3547.zip

Re: AT89LP2052 connection

wimac — Tue, 30 Jun 2020 15:35:49 +0530

How did you know that it is not 8051.
Mirza123

It is really important when dealing with a new chip to have a good read of the datasheet. In this case you need to read the sections dealing with I/O Ports.

Have a look at page 8, section 7.7 and section 15 starting on page 20 and see if that helps.

Re: AT89LP2052 connection

Mirza123 — Tue, 30 Jun 2020 14:09:23 +0530

It seems ports on the AT89LP2052 is not like on the 8051,
so your program may not work.
ExperimenterUK

How did you know that it is not 8051.
I have put full week dealing with this chip but i did not work.
I have attached the circuit schematic also which i am using.

Re: AT89LP2052 connection

ExperimenterUK — Tue, 30 Jun 2020 14:04:43 +0530

It seems ports on the AT89LP2052 are not like on the 8051,
so your program may not work.

If you have not got it working, let me know and I'll look into
what is needed to set up the ports.

AT89LP2052 connection

Mirza123 — Thu, 25 Jun 2020 21:37:23 +0530

Hello!
i am trying to use AT89LP2052 ( AT89LP2052 http://ww1.microchip.com/downloads/en/devicedoc/doc3547.pdf) for LED to turn on and OFF. but i am confused with the connections.
I have used i have loaded the program by using 8051Flash program. For writing the program i have used 8051-Ready board(https://download.mikroe.com/documents/starter-boards/ready/8051/8051ready-manual-v100.pdf) and mikroprog-8051 (https://www.mikroe.com/mikroprog-8051).

here is the code which i have learnt from your course.

#include




// for 11.0592MHz Crystal



void delay(unsigned int count)



{



unsigned int i;



while(count)



{



i=115;



while(i>
0)



i--;



count--;



}



}



void main()



{



while(1)



{



P1 = 0x00;



delay(1000);



P1 = 0xff;



delay(1000);



}



}

Can you please help me with the connection?

Re: Need help with Schematics

ExperimenterUK — Thu, 18 Jun 2020 03:12:49 +0530

It is about capacitor? i should put it between Vcc and gnd?

Yes.

I Dont understand what is wrong with reset.

There is nothing wrong with your reset.
It is just that you need to turn the power off to reset the circuit.
If you add a push button you can do a reset while leaving the power on.
Sometimes that is useful for testing and programming.

Voltage source is 5V. Should i use voltage regulator?

No a five volt supply is fine.
I was just looking for reasons why your professor might be was worried.
He might think your supply is more than five volts.

Re: Need help with Schematics

cerouno — Wed, 17 Jun 2020 16:07:59 +0530

Take another look at the power supply to the LCD.
A reset button is handy for testing.
If the supply is no more than five volts, I don't see why the supply,
or anything else, would burn out.
I might have missed something.

ExperimenterUK

It is about capacitor? i should put it between Vcc and gnd?
Dont understand what is wrong with reset.
Voltage source is 5V. Should i use voltage regulator?

Re: Need help with Schematics

ExperimenterUK — Wed, 17 Jun 2020 07:31:30 +0530

Take another look at the power supply to the LCD.
A reset button is handy for testing.
If the supply is no more than five volts, I don't see why the supply,
or anything else, would burn out.
I might have missed something.

Need help with Schematics

cerouno — Tue, 16 Jun 2020 22:58:03 +0530

I am working on Smart parking project.
Here is my schematic.
I sent this to my professor and he said it is not right, i am not sure why. Also he said if i connect this to power source it will burn the source.
I am new at this so i really need help.
What am i doin wrong?

8051 MULTIPLICATION

xrxx — Thu, 30 Apr 2020 16:29:47 +0530

BCD MULTIPLICATION
Assume that you have to 2 BCD numbers in 2 registers/memory locations.
Write a subroutine to multiply these 2 numbers and put the result in a different register set/memory location. The maximum number can be 9801 (99*99=9801). So you need 2 bytes to store 4-BCD digits.
Execute your program in the simulator and get screenshots at several steps during the execution.
Put your code and screenhots in a zip file seperately and submit the zip file as name_surname_id_hw1.zip
SWAP is good instruction to switch lower and higher nibbles (4-bits) in A.
Repeat the steps we follow on the paper.

Guys, can u help me for this? pleaseeeee

Re: Detect magnet position with Hall effect sensor

liqian — Tue, 28 Apr 2020 14:56:31 +0530

I happened to see your post and I got many useful pieces of information, thank you so much

Re: problem real pic simulator MPLabx

ExperimenterUK — Tue, 28 Apr 2020 13:51:45 +0530

The code is hard to read.
Please zip it and attach it to your post.
Before you zip, it please add lots of comments to explain how each part works.
Imagine you are explaining each step to someone who has never seen your project before.
This is good practise, because if you come back to this code in a few months
you will have forgotten how it works.
Also please zip and post a circuit diagram, even if it is only a rough sketch.

Re: problem real pic simulator MPLabx

rogermado — Sun, 26 Apr 2020 11:23:19 +0530

@ExperimenterUK, thanks for your reply. You'll find the code below. thanks again RogerMado

;**********************************************************************
; This file is a basic code template for assembly code generation *
; on the PIC16F877A. This file contains the basic code *
; building blocks to build upon. *
; *
; Refer to the MPASM User's Guide for additional information on *
; features of the assembler (Document DS33014). *
; *
; Refer to the respective PIC data sheet for additional *
; information on the instruction set. *
; *
;**********************************************************************
; *
; Filename: xxx.asm *
; Date: *
; File Version: *
; *
; Author: *
; Company: *
; *
; *
;**********************************************************************
; *
; Files Required: P16F877A.INC *
; *
;**********************************************************************
; *
; Notes: *
; *
;**********************************************************************

list p=16f877A ; list directive to define processor
#include ; processor specific variable definitions

__CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _RC_OSC & _WRT_OFF & _LVP_ON & _CPD_OFF

; '__CONFIG' directive is used to embed configuration data within .asm file.
; The lables following the directive are located in the respective .inc file.
; See respective data sheet for additional information on configuration word.

;***** VARIABLE DEFINITIONS
w_temp EQU 0x7D ; variable used for context saving
status_temp EQU 0x7E ; variable used for context saving
pclath_temp EQU 0x7F ; variable used for context saving

CNT_7_SEG EQU 0X24

ORG 0x000 ; processor reset vector
nop ; nop required for icd
goto main ; go to beginning of program
ORG 0x004 ; interrupt vector location
movwf w_temp ; save off current W register contents
movf STATUS,w ; move status register into W register
movwf status_temp ; save off contents of STATUS register
movf PCLATH,w ; move pclath register into w register
movwf pclath_temp ; save off contents of PCLATH register
test_1
BTFSS INTCON,INTF
goto test_2
call service_interrupt_2
test_2
BTFSS INTCON,RBIF
goto Sortir
call service_interrupt
Sortir
movf pclath_temp,w ; retrieve copy of PCLATH register
movwf PCLATH ; restore pre-isr PCLATH register contents
movf status_temp,w ; retrieve copy of STATUS register
movwf STATUS ; restore pre-isr STATUS register contents
swapf w_temp,f
swapf w_temp,w ; restore pre-isr W register contents
retfie ; return from interrupt
main
call ConfigPortB ; RB3 en output RB0:RB2 en input RB4:RB7 en input
call ConfigPortD ; configuration du portd en output
call ConfigPortC ; configuration de RC0 en output
call ConfigPortA ; configuration du porta en input

call configinte

BSF PORTC,RC0 ; alimente le 7 segments
movlw 0X3f
movwf PORTD
boucle
reset_zones
BTFSS PORTC,RC1
goto boucle_reset
movlw 0Xf7
movwf PORTD
boucle_reset
goto boucle
goto $
JUMP_TO_BANK1
BSF STATUS,RP0
BCF STATUS,RP1
RETURN
JUMP_TO_BANK0
BCF STATUS,RP0
BCF STATUS,RP1
RETURN
ConfigPortA
CALL JUMP_TO_BANK1
MOVLW 0X11
movwf TRISA
call JUMP_TO_BANK0
return
ConfigPortB
CALL JUMP_TO_BANK1
movlw B'11111111'
movwf TRISB
CALL JUMP_TO_BANK0
return
ConfigPortD
CALL JUMP_TO_BANK1
MOVLW 0X00
MOVWF TRISD
CALL JUMP_TO_BANK0
return
ConfigPortC
CALL JUMP_TO_BANK1
movlw 0XFE
movwf TRISC
CALL JUMP_TO_BANK0
return
configinte
CALL JUMP_TO_BANK1
movlw 0X98
movwf INTCON
movlw 0X80
movfw OPTION_REG
CALL JUMP_TO_BANK0
return
service_interrupt
movf PORTB,W
BCF INTCON,RBIF
movwf PORTB
BCF INTCON,GIE
TEST1
BTFSS PORTB,RB4
GOTO TEST2
GOTO SHOW1
TEST2
BTFSS PORTB,RB5
GOTO TEST3
GOTO SHOW2
TEST3
BTFSS PORTB,RB6
GOTO TEST4
GOTO SHOW3
TEST4
BTFSS PORTB,RB7
GOTO end_interrupt
GOTO SHOW4
SHOW1
movlw 0X06
movwf PORTD
GOTO end_interrupt
SHOW2
movlw 0X5B
movwf PORTD
GOTO end_interrupt
SHOW3
movlw 0X4F
movwf PORTD
GOTO end_interrupt
SHOW4
movlw 0X66
movwf PORTD
GOTO end_interrupt
end_interrupt
return
service_interrupt_2
BCF INTCON, GIE
BCF INTCON, INTF
movlw 0XF7
movwf PORTD
return
end

Re: problem real pic simulator MPLabx

ExperimenterUK — Sun, 26 Apr 2020 03:12:33 +0530

Some simulators handle displays better than others.
If you post as much of your code and circuit diagram as possible
we can try it in "Real Pic Simulator" and Proteus.

Meanwhile try writing test code to do very simple things
such as displaying just one character.
First find what works.. then add to it.