Take a break

Gadgeteer POE Module schematic

2012-06-01T09:44:00.002-04:00

It has been awhile since I posted about my POE Module for Gadgeteer. It works great and I am happy with it in general. I am also looking at some other designs for v2. It is work in progress.

Meanwhile here is the schematic for v1.0. Enjoy!

MAKE Beta Team!!!

2012-04-21T14:15:00.003-04:00

Great news! I just got Welcome email from MAKE. I got accepted to the MAKE Beta Team! A number of makers around the world has been selected to beta-build some projects that might get into the MAKE Magazine.

http://blog.makezine.com/2012/03/15/make-beta-team-join-us/

I am very excited about it and looking forward to build my first project. Looks like we might start for the fall issue No. 32. Thank you MAKE!

Gadgeteer DaisyLink - Protocol

2012-02-25T14:34:00.004-05:00

If you have visited my blog before, you most likely know that I have built several modules for the Microsoft Gadgeteer platform. So far I have only tried simple modules (with the exception of POE module). What I haven't tried yet is a DaisyLink module. DaisyLink module is a special (smart) breed of modules because it has to have a dedicated controller in order to communicate with the main board. Recently I had a chance to finally built a module like that and I would like to share my experience in that area. There is a lot to write about, so I will do it in multiple posts. This is the first post where we look at the DaisyLink protocol.

Why does a DaisyLink module need its own MCU on board? A DaisyLink module can be a part of a long chain of modules connected to each other.

One chain can have more modules than the number of pins that are available on the socket that the chain is connected to. So we would need a smart way of communication that requires a minimal number of physical connections. The main board needs a way to distinguish and address each individual module in the chain as well. In other words, the main board should be able to assign an address to a module and the module should remember that address in some sort of memory. The communication between the main board and a module should also be generic enough and independent from the actual functionality that is provided by that module. In order to meet these requirements the Gadgeteer team designed a special protocol - the DaisyLink protocol. This protocol has to be implemented on a module's micro controller.

Memory Map

Before we start looking at the protocol details lets take a look at the module's memory organization. As mentioned before, each module is given an address by the main board and that address is stored, along with some other settings, in the module's Memory Map. The total size of the Memory Map is 256 bytes. The first 8 bytes are allocated for the DaisyLink infrastructure.

Remaining 248 are available for the module. This module-specific area of the map is the mechanism of controlling the module. As the module designer, you will lay out this map by defining your own registers that required to tell your module what to do as well as registers to store results of these actions if needed. For example this is the map layout for the GHI's Smart Multicolor LED Module.

For example, byte at address 11 controls mode of the module (On, Off, Blinking, etc.)

Wiring

The DaisyLink Protocol is based on I2C. I2C is a common protocol supported on all major MCUs available today. It requires two wires - one for clock (SCL) and one for data (SDA).
If you have never worked with I2C, I strongly recommend to read about it on the Internet. There are plenty of tutorials available (I have included one link at the end of this post).
I2C bus requires two pull-up resistors for both lines. At first, it would make sense to put these resistors on the main board, but that would limit the use of the socket. So the decision was to have a pair of pull-up resistors (10k) on each module. Each module should be able to switch these resistors on and off. This will ensure to have only one pair of active resistor on the bus. The protocol specification shows how to use a transistor to implement a switchable pull-up. We will be using the other way of doing it by utilizing tri-state ports on the micro controller. For example, in the schematic below, changing the pin 25 to digital out and setting it to HIGH will enable the SCL pull-up resistor; switching the pin to digital input will disable the pull-up. Same applies for the pin 26 for the SDA line.

In addition to I2C wires, DaisyLink requires two more connections, one to the module or main board up the stream and one to the module down the stream. Here is the schematic view of both connectors:

Upstream and downstream lines are pulled high on each module using 10K pull-up resistors. Pulling these lines down will allow a module and/or the main board to signal each other about the state changes. Notice the extra unused pins on each socket (pins 6,7,8 and 9). We will use them later during actual implementation of the module.

Module states

At any given time a DaisyLink module can be in one of the four states. Below is the table from the official specification document that describes the four states as well as the state of the bus for each module state.

State	Upstream	Downstream	I2C pull-ups
Reset	Driven low by main board	Driven low by module	Disabled
Setup	Released by main board and pulled high by module's pull-ups	Driven low by module	Active
Standby	Pulled high by module's pull-ups	Released by module and pulled high by module's pull-ups	Active
Active	Pulled high by module's pull-ups	Pulled high by module's pull-ups	As set by the main board

Lets look at each state in more details.

Reset

On a power up each module is in the Reset state - the upstream line is driven low by the upstream neighbor. If it's the first module in the chain, the upstream neighbor is the main board. Downstream is driven low by the module (to ensure that all the other modules in the chain stay in the Reset state). At this state a module should listen for the level change on the upstream line. As soon as it goes HIGH it should proceed to the next state. (If upstream line goes low again at any state, this takes the module back to the Reset state).

Setup

First thing to do after switching into the setup state is to activate pull-up resistors and enable I2C interface on the micro controller. Remember that every module is I2C slave, so if your micro controller has different initialization for master and slave, make sure you are using it as a slave device. The default I2C slave address during setup is 127. During the Setup stage the main board reads module's register at address 2. This is the DaisyLink protocol version (current number is 4). If the module returns correct version number then the main board assigns a new unique ID for the module by writing it to the the modules register at address 0. As soon as the new ID is assigned, the module goes into the Standby state and should release the downstream line. This will let the next module in the chain to move from Reset to Setup state.

Standby

Nothing to do here. During this state the main board tries to read protocol version of the next module that will respond to the default address of 127.

Here is the image of the state of the neighbor lines (0 - upstream, 1- downstream).

(The image above is taken from SUMP Logic analyzer software . For hardware I used BusPirate )

Reading and writing of the memory map is done by implementing standard I2C-based EEPROM interface.

A write transaction comprises the following bytes:

A start condition.
The I2C ID with the write bit set (ID 1–127, LSB 0=write).
The memory address to write (0–255).
One or more bytes of data to write.
A stop condition.

A read transaction includes the following bytes:

A start condition.
The I2C ID with the write bit set (ID 1–127, LSB 0=write).
The memory address to read (0–255).
A repeated start condition (or stop condition and then start condition).
The I2C ID with the read bit set (ID 1–127, LSB 1=read).
One or more bytes of data that are written by the subordinate device clocked in by the master according to the I2C specification.
A stop condition.

I2C transactions to read version number:

I2C transactions to assign new ID to the module:

Active

After the main board is done assigning unique IDs to each module in the chain, it will notify all the modules, except the last one, to turn off the pull-up resistors. This is done by writing to the configuration register at address 1 in the memory map. Bit 0: low=pull-ups are off, high=pull-ups are on. The main board will also write to the Bit 1: low=module in Active state, high=module is not initialized.

I hope I have provided enough details about how the DaisyLink protocol works. If you have any questions/suggestions feel free to leave a comment. In the next post I will show my implementation of the protocol on Arduino.

Gadgeteer DaisyLink Series:

Gadgeteer DaisyLink - Protocol (this post)
Gadgeteer DaisyLink - Arduino Library
Gadgeteer DaisyLink - Arduino Sketch

Links:

DIY Chronodot for Bulbdial Clock

2012-02-01T01:43:00.000-05:00

A friend from work gave me a really nice present this Christmas - Bulbdial Clock Kit made by Evil Mad Scientist Laboratories. This clock is excellent addition to my collection of Ice Tube Clock and Monochron Clock. I have really enjoyed building it. It looks so cool with all its RGB LEDs. There is an optional component that you can add - a real time clock (RTC) with battery back up. It is called Chronodot RTC. All it does is ensure that clock is still ticking when main power source is removed, that way you don't have to reset the clock every time power cord is unplugged. A nice feature to have on any externally powered clock. You can buy one, but where is fun in that?! So I have decided to build my own. By the way this is what Chronodot looks like:

I like the round shape of the Chronodot board. Luckily RadioShack sells Round PCB Kit. It is a set of 5 round boards of different sizes. The middle one is the perfect fit for our goal.

Hmm... What else do we need?

Part	Description
	Real time clock - DS1307
	32.768 KHz, 12.5 pF watch crystal
	12mm coin cell holder
	12mm 3V lithium coin cell - CR1220
	Straight male header.Two sections 4 pins each
All parts photos by Adafruit Industries Adafruit.com

We will also need some wire. I am using Kynar wire 30AWG. The pcb board is one sided board so we will solder all components on one side and will use wire jumpers to connect corresponding pins. Lets start by taking a look at the pin out of the DS1307.

We will use RTC for time keeping only (it also can be used for square wave generation), so we will not be using SQW/OUT pin.

Here is the schematic of required connections:

and board view:

I will not get into details on soldering - there are a lot of tutorials about soldering on the Web.
This is what it looks like with everything soldered on the board.

And finally painted and installed on the clock:

This is it! Thank you for stopping by.

Arduino DaisyLink module for Gadgeteer

2012-01-24T02:11:00.001-05:00

This is a proof of concept for Arduino based Gadgeteer DaisyLink module.The Gadgeteer DaisyLink protocol allows to chain up to 126 various modules on one socket. The protocol is based on I2C-based EEPROM interface.

In this picture I have two modules chained on one socket. The first module is GHI's multicolor led, the second is Arduino led module. More details later...

IR LED Array Module for Gadgeteer

2012-01-19T22:41:00.000-05:00

Andrew Duthie (aka Devhammer) is working on a very cool project involving infrared helicopter, Kinect and Gadgeteer. He needed a module for Gadgeteer to control his helicopter. Here is what he came up with:

You can find more details on his blog and in this thread on TinyCLR.

Show your skills

2011-12-27T11:13:00.000-05:00

I like the Iron on Patches that you can get from Adafruit. I don't own any but I still like them. Lahack.com created a script that will generate a wall of skills image using Adafruit's patches. Here is mine:

FEZ Cerberus on horizon

2011-12-18T21:41:00.001-05:00

Some information started to show up on the forum. It is about a new mysterious (well, not as mysterious now) offer from GHI Electronics - FEZ Cerberus. For now there is only this image available:

It looks like GHI is very serious about supporting Gadgeteer and I am sure this new main board will be as great as the other two.

DuinoProto - a bridge between Gadgeteer and Arduino.

2011-11-09T19:28:00.000-05:00

I am a big fun of the Microsoft Gadgeteer (if you have not figure it out by now :) ). Right now there is pretty much only one company in the US that is actively developing Gadgeteer modules and boards - GHI Electronics. So I follow that company very closely. Today they put up another Gadgeteer related product - DuinoProto. It is not a Gadgeteer module (it doesn't follow the standard), but rather a solution that should help prototyping modules much easier and also should bridge the gap between Gadgeteer and existing shields and modules for Arduino(s). There are other scenarios of using it as well.

As you can see it has an Arduino shield form factor. There is also a nice prototyping area and a place to put up to four Gadgeteer socket connectors. I am definitely going to try it as soon as I have more time and get my hands on one of these.

Oh, did I mention that you can get one for free (some conditions apply)?! Here you go!

FEZ Hydra 100% OSHW .NET Gadgeteer main board

2011-11-08T22:21:00.003-05:00

I wrote about FEZ Hydra in my last post and now we have all the details. It is 100% open source including hardware design as well as the port of .NET Microframework that can be compiled using GCC toolchain. According to Gus Issa, this board was designed with three main goals:

Open source
Low cost
More Power

Lets take a closer look and compare it to FEZ Spider.

The first noticeable difference is in size 3.42" x 2.44" vs 2.25" x 2.05". There is also a very nice OSHW logo in the center of the board and absence of configuration switches. The FEZ Hydra has 14 .NET Gadgeteer compatible sockets same as the FEZ spider, although there is a difference in the type sockets and number of the sockets. FEZ Hydra is missing H (USB Host), C (CAN Bus), E (Ethernet) sockets. (Even though there is no E socket, the board can still be connected to internet using SPI based Ethernet module). I suspect that not having H, C and E is part of the low cost and open source measures. The board is definitely cheaper ($79.95) compared to FEZ Spider ($119.95) and no doubt has more power - 240Mhz ARM9 Processor (running at 200Mhz) compared to 72MHz ARM7 on Spider. These are the top main differences between the two boards. Overall FEZ Hydra is a very great offer.

I am one of the few lucky ones who will get the board, hopefully this week, and I will be back with more information on FEZ Hydra

New Gadgeteer main module from GHI - 200 Mhz FEZ Hydra

2011-11-04T13:58:00.001-04:00

The news has been on the forum for awhile now, but now we have a full image of the board.

Other side:

And what is the most exciting is that everything is completely open source.Here is the quote from Gus Issa:

"GHI has seen the great value in open source hardware and FEZ Hydra is finally here. An official announcement comes early next week but for now...

FEZ Hydra is 200/240Mhz open source hardware. We give you hardware/software design files, everything A to Z. The board is powerful enough to run even linux!

What is so special about this board is that its firmware is compiled with open-source GCC compiler. Community will be able to modify and contribute easily. The board is designed in EAGLE. One of GHI trade secrets is the way we layout 0.8mm BGAs and now it is all open."

And another interesting moment:

"We hope this new FEZ will meet your expectations and we hope the price will draw a huge smile on your face."

Can't wait!

Are you a Gadgeteer?

2011-10-13T09:49:00.000-04:00

Are you a Gadgeteer? posted a nice unboxing video of the FEZ Spider Starter Kit,which I own as well. Although mine didn't come in a nice plastic box, but I was one of the first 5 to get it a month earlier of the official shipping date.

Chucky module for Microsoft Gadgeteer (Wii Nunchuk connector)

2011-10-13T01:05:00.003-04:00

This is my third module so far. It is the simplest one. It has no components beside the connector.

With the soldered connector

Nunchuk fits perfectly and securely

I am also experimenting with Google SketchUp and EagleUp. Here is the result

Gus Issa from GHI Electornics has suggested to make a video of all three modules in action. I will try to do that sometime and will make a post about it.

This module is available for sale. Information on how to order is on TinyCLR Community modules page.

Piezo buzzer module for Microsoft Gadgeteer

2011-10-12T00:29:00.001-04:00

I made another module for Gadgeteer. If you need to add some noise , this module should help:

With connector and buzzer:

I will make another post later about the driver and some code example(s).

Gadgeteer POE Module Test

2011-10-11T00:31:00.003-04:00

Tonight I have tested the module. The test application gets rss feed and shows first 4 entries on the display module. Everything worked as it should.

The module is compatible with GHI's Ethernet J11D Module. So I did not write module's driver for testing. I still have to do that, so it will be properly used in the Visual Studio Designer.

Once this is done I will upload everything to the Gadgeteer Codeplex.

Gadgeteer POE Module is here

2011-10-10T00:09:00.002-04:00

I have designed POE Module for Microsoft Gadgeteer. I received pcb boards last week from DorkbotPDX (awesome service by the way). The boards are of a great quality and look very nice.

The only issue is that this board has to be red, because it is a power module, but DorkbotPDX only offer purple boards for now. So if the module is offered to the public it has to be red (according with specification). Here is another picture of two modules side by side. As you can see module on the right is populated with all components.

To be continued...

Blog move is done!

2011-10-02T09:41:00.001-04:00

Moved my blog to Blogger. It was pretty easy. I have to finalize some last details, but so far it is looking good. I had to move each post manually, but there was not a lot to move. I hope I will have more time to put more content here, but you never know.

Fritzing part for USBizi DevSys

2011-04-04T20:01:00.000-04:00

This is the last part (for now) for USBizi DevSys. The board is made by GHI Electronics. Some people still have this module, but you can't buy it anymore. I do have it and I would like to have a part for it.

Download USBizi DevSys Fritzing part.

Fritzing part for FEZ Domino

2011-03-28T19:58:00.000-04:00

Finished another part for FEZ Domino:

Download FEZ Domino Fritzing part

Fritzing part for FEZ Panda II

2011-03-22T19:56:00.000-04:00

Here is the Fritzing part for FEZ Panda II

Download FEZ Panda II Fritzing part.

Stay tuned for other FEZ parts. FEZ Domino is next!

Fritzing part for FEZ Panda

2011-03-14T19:54:00.000-04:00

Here is the Fritzing part for FEZ Panda

Download FEZ Panda Fritzing part.

Stay tuned for other FEZ parts. FEZ Panda II is next!

Fritzing part for FEZ Mini

2011-03-11T19:51:00.000-05:00

When I was learning about Arduino, I always liked images that show how to connect different components to Arduino board. Like the one below:

I didn't know how these images are created until I have discovered Fritzing. "Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to work creatively with interactive electronics."

Fritzing comes with hundreds of components and it allows you to create your own parts.

I am using FEZ boards a lot lately, and I want to have a Fritzing part for FEZ boards. Since I couldn't find any I have decided to make these parts. Here is my first completed part for FEZ Mini:

Download FEZ Mini Fritzing part.

Stay tuned for other FEZ parts. FEZ Panda is next!

Managed driver for Monochrome 128x64 OLED graphic display

2011-01-15T19:42:00.000-05:00

I got my hands on the new Monochrome OLED graphic display from Adafruit. I absolutely love it. This is a great addition to my gadgets.

My main dev board is FEZ Panda from GHI Electronics. It is a .Net Micro Framework device with a great set of features. I looked for a managed driver for the display and couldn't find any, so I have ported the arduino library that is provided by Adafruit.

It didn't work from the first try. I have arduino board as well, so I have tried the orginal library with no success. I almoust got to the point of returning the display, but decided to take a closer look and found that there were two bridges on some pins at the back of the display board.

I have "fixed" the bridges with a hobby knife and my driver worked right away!

You can find the full source code here.

Ice Tube Clock

2010-01-30T18:39:00.000-05:00

January 30 was not a usual winter day for Chesapeake, VA.

I have been here for more than 5 years and I don't remember seeing so much snow that actually stays on the ground. So I have decided to finish Ice Tube Clock. I have bought 5 pcb boards from Adafruit site. They sell full kit as well. The rest of components I got from various sources and the tube itself is from eBay.

I don't have access to a laser cutter so I have used my Dremel scroll saw to cut the case. Here is the finished product:

Closer look

Chris came up with the idea of displaying temperature in addition to time using wireless temperature sensor. We are going to try it when we have more free time.

Thecus N4100PRO NAS SABnzbd module

2010-01-17T17:49:00.000-05:00

I got Thecus N4100PRO NAS this summer and have been looking for a usenet module for it since then. Decided to do another search today and guess what I have found:

http://www.10741.nl/thecus-n5200pro-sabnzbd-module

flex/postgres fanboy ;) made the module for N5200Pro. I have just tried it on my N4100Pro. Works like a charm!