Ben's Blog

Last Sunday, UMIEEE together with UMARS (two University of Manitoba student groups I am a part of) got together to hold an embedded systems workshop on campus. We helped teach a bunch of fellow students the basics of designing and programming embedded systems. We used TI’s MSP430 Launchpad development kit, a super low price dev kit, so that everyone could go home with their project and continue experimenting. While the Launchpad (or rather the MSP430 microcontroller on the board) isn’t as easy to program as something like an Arduino, the Launchpad allowed us to convey some of the more fundamental principles of embedded design like bit masking and timer interrupts.

The morning consisted of getting the tools setup and getting a “hello world” application running. The official tools are Windows only, but the Launchpad does work with Mac and Linux once you figure out how to install everything. It actually seemed to work better, due partly to the fact that the tools are open source and hence not crippled versions of paid software, but also because the environment was less integrated (ie you use a text editor, a compiler, and a debugger all separately instead of a full blown IDE like they use in Windows). The Windows users ofter had to restart the whole IDE when one part of the system locked up for unknown reasons.

After lunch, we dove into making a much more ambitious project: an LED chaser. The design specifications we gave to everyone was something to the effect of “when you press a button, your chain of LEDs will light up one by one until you reach the final one in the string.” The idea was then to replace the final LED with the next person’s button input pin and watch as the lit LED ran across everyone’s boards. The day before, the volunteers leading the workshop got together and pumped out a quick (and admittedly buggy) code for this, so we felt it was an attainable project. We nudged everyone along, showing them how to light individual LEDs, use interrupt pins and timers, and wire up buttons with pull up resistors. I think only a few people actually got the final chaser working, but everyone had a good time.

You can see an abstract for the event along with a bunch more pictures here.

Next month I am going to be one of the instructors in an MSP430 Launchpad workshop at school and so I am testing out this “quick installer” for Mac OS X. In the installer readme, the author wrote this:

This package does not provide an easy way to uninstall. If you wish to remove the toolchain, google for “lsbom uninstall” and follow the procedure while optionally shrieking curses upon Apple’s immature packaging system.

Hopefully I won’t have to uninstall.

Yesterday I had the honour of attending a hackathon with Winnipeg’s new hackerspace, SkullSpace. I brought my CAN bus boards to do some soldering and also did some lock picking. You can read more about the event on their blog. They are in the process of getting permanent space together, so we met at the Red River College campus (it is a sweet set of buildings and you should check it out if you can). Once they have the legalities and funding (via donations and paid memberships) then they will start equipping a space. I’m really looking forward to it!

Last weekend I had the privilege of attending the 2011 Western Engineering Competition (WEC) at the University of Sasketoon. The activities were a blast and the Senior Design competition was great. After presenting our design, we felt that we did really well. The other teams also did great jobs and I’m sure it was very tough for the judges to make their final decisions. Sadly, we did not win, but we had a great time competing and getting to know fellow students from across the country. We took some video of our robot/tractor and I have embedded them below.

WEC 2011 – It’s alive! from Benjamin Bergman on Vimeo.

This was the first time we had our robot running in it’s final configuration at WEC 2011 Senior Design.

WEC 2011 – Hay Bail Challenge from Benjamin Bergman on Vimeo.

In this challenge, we had to remotely control the robot to lift a “hay bail” (a marshmallow, in this case) and place it in a small cup. This was one of the easier challenges for the day.

WEC 2011 – Pasture Crossing Challenge from Benjamin Bergman on Vimeo.

In this challenge, we had to remote control our robot tractor and drive it across the “pasture” (represented here by a steep, ~40˚ slope covered in a plastic tarp and a layer of very soft dirt). We had to avoid hurting any livestock or the environment (ie. the trees). While it looks like we did quite poorly, everyone got about the same distance on this one.

WEC 2011 – Grain Sorting Challenge from Benjamin Bergman on Vimeo.

In this challenge, we had to separate the “wheat” (marbles) from the “chaff” (rice) using our robot. The robots built by most of the other teams used the vex panels themselves (they have lots of holes) to filter out the marbles, but this was slow and required agitation. Our robot used some rails on end that left gaps barely wide enough to catch the marbles and let the rice immediately fall to the ground.

WEC 2011 – Manure Moving Challenge from Benjamin Bergman on Vimeo.

In this challenge, we had to remotely control our robot to move a pile of “manure” (loose dirt) from it’s initial location across a line. Our performance in this challenge was not great as it was hard to maneuver our robot in the tight space, plus our scraping mechanism did not reach as low as we would have liked.

WEC 2011 – Barrel Race Challenge from Benjamin Bergman on Vimeo.

In this challenge we had to autonomously get our robot to navigate a figure 8 around a pair of “barrels” (pop cans) and then complete a lap of an oval track. The oval was no problem, and in our testing we could do it very quickly, but the preceding figure 8 in the soft dirt made it impossible to line up for the lap. None of the competitors were able to complete this challenge. Since it was worth 50% of our demonstration mark, that put a lot of weight on our presentation.

WEC 2011 – Barrel Race Lap Demo from Benjamin Bergman on Vimeo.

After the competition, we wanted to demonstrate our completion of a lap of the barrel race track, just for fun. Some other teams also demoed their lap code, but ours seemed to be the fastest.

WEC 2011 – Attempted Marshmallow Destruction from Benjamin Bergman on Vimeo.

During building, we found that our gripper arm had a lot of torque, so after competition we tried to cut a marshmallow in half. Sadly, the gears kept slipping since we had stressed out all of our mounts during competition, but we had fun anyway.

WEC 2011 – Attempted Pop Can Destruction from Benjamin Bergman on Vimeo.

After competition we tried to crush a pop, but our gears kept slipping as the mounts had been stressed during competition.

WEC 2011 – ROV from Benjamin Bergman on Vimeo.

After playing with our robot for a bit, we decided to attach a phone to the arm. This clip was just to get a “first person” clip, but we later set up an IP webcam server from a phone to remotely control it. It was a bit laggy, but tons of fun.

As some of you are aware, I am a member of the University of Manitoba SAE (Society of Automotive Engineers) Formula Hybrid team. The major project that I have been working on for a while now is a CAN bus controller Arduino shield. The system is based on the one designed by Mike Sefton last year. We are using the same CAN interpreter because the manufacturer was generous enough to donate some chips to us. These chips work well, but they are designed to be used with an OBDII reader, so we are using a few work arounds to get the system to work for us the way we need.

Aside from some simple changes to the circuit, there are two major changes to the system. First, I added a the NUP2105L chip to the CAN bus to give us some over-voltage protection. The major cause of failure last year was over-voltage, which is always a concern when dealing with electric vehicles. The second change was to allow an outside system to communicate with the CAN controller over a serial connection. Last year the CAN devices were controlled directly by the Arduino, but this year the Arduino is basically a middle man that can do some processing of commands if needed.

For the hardware design, I decided to try out a few open source tools. I first tried KiCad because it was more cross platform and a fully integrated suite. There were some things I didn’t like about it though (although I may have just been looking in the wrong place for the feature I thought was missing) so I decided to try out gEDA. I personally liked the feel of gschem better than KiCad’s schematic editor, and the PCB software seemed quite good to me too. The workflow between tools is a bit less intuitive, requiring a few terminal commands, but I am quite comfortable with the command line, so I can see myself using gEDA much more in the future.

The files for the hardware design are posted here: HARDWARE

The firmware for the Arduino is posted here: FIRMWARE

The firmware is currently a very basic repeater but will likely see changes once we start figuring out what specific features we will need. Feel free to post a comment or send me an email if you have any questions about the design.