I’ve put together pictures of the CAN bus “sniffer” project I made recently. Here is a picture of the “sniffer” hardware implementation, connected to another project that reads data from a GPS module (that small square thing in the lower right corner of the photo).

The basic idea is that the GPS interface board (the green board at the bottom of the picture) is reading data from the GPS module, doing some processing of the data, then forwarding latitude and longitude over the CAN bus to anyone who wants to listen. Someday I’m planning to implement a robot that will use that data to help navigate.

My robotics library contains the “sniffer” demo program (it uses the same hardware as the can_mcp2515 demo) as well as the code I wrote to parse the GPGGA-style sentences from a GPS module like this one.

Another thing we did on Salt Spring Island was to purchase art.

The picture is titled Somebody’s in the Kitchen and was painted by Jerry Davidson, a resident of Salt Spring. He painted it with pastels and we were very impressed with the detail he achieved with such a soft medium.

Its just delightful but my photo doesn’t quite capture the details as well as you might see in person. As you imagine, we fell in love with it as soon as we saw it. It was framed with very reflective glass so we’ll have to replace that at some point, but there isn’t any rush.

And unlike the last one, this time we actually checked to see that it would fit into the car.

It’s that time of year again! The annual Robothon is coming September 21-23 at Seattle Center.

This event is always a lot of fun. If you aren’t familiar with it, check out some of my pictures from 2005 and 2006. There is always fun things to see and of course some of the robots are really amazing.

I’ll be taking a couple of minisumos (The Thin Man and Velox) with me this year, but I haven’t had time to work on any other projects. I had hoped to have a micromouse robot ready but I had to give up that project due to lack of time (other things seems to always interfere). However I’m sure I’ll be busy as there are plenty of events to watch even if I don’t have a robot for it.

Check out the Robothon site for details and hope to see you there!

We just returned from ten days away on Salt Spring Island doing not a lot. It was one of those holidays where we didn’t have any plans except to relax, drink some wine, read some books, and enjoy ourselves. Except that I kept myself busy with a couple of electronics projects and my ever-expanding library of robotics-related code.

I’ve become really interested in using the Controller Area Network technology to have multiple processors communicating together. While researching the options I found this project: CAN-CAN. I liked the simplicity of using the Microchip MCP2515 and it’s less expensive than using one of the Atmel processors with built-in CAN support. And this project really made it easy, I starting thinking it was something I could probably do. So I did! Here is the schematic for my version.

My first project used two separate ATMega8 processors talking to each other over a CAN bus. I read through the source code from the original project but figured I could build my own version, integrated into my own library of code for my robots. I made a number of improvements, making it easier to configure for different hardware. The main program sends a short text string from one processor to the other, where the case is reversed (uppercase to lowercase and vice versa) and a reply is sent back. Here is a picture of what it looks like in action on the screen.

I spent part of my holiday cleaning up the code and implementing interrupt-driven TX and RX. The fun didn’t stop there though. I wrote a second program that “sniffs” the CAN bus and pretty-prints out each message. This has turned out to be very useful while developing other programs with the library (more on this later).

I’ve packaged up my entire library plus these two demonstration programs and made it available for download here. There isn’t a lot of instructions but I’ll probably try to put together something in the future (maybe my next holiday?).

At work I spend a lot of time thinking about and looking at HTTP traffic. So when someone figured out a way to make that funny, I pay attention. This comic is really clever. Be sure to read the page source to squeeze out every bit of funny.