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Traxxas Now with More Horsepower

April 9, 2010 Leave a comment

Okay, perhaps the title is a bit misleading…more computational horsepower. Today, I finally got around to mounting the TS-7800 from Technologic Systems. It’ll be running all the main processing and communicating with the micro controller via a serial port.

Additionally, we’d failed to include a shiny “GO” switch anywhere in the system so I used the DIO port on the ARM to read in a signal to indicate the mission should execute. If you are looking for sample code for the TS-7800, Eric Robishaw’s example is a good start.

If that’s a little much to parse, here’s my simpler variant. It does far less but is a test bit of code that shows the reading without a lot of extra capability.

I’ll leave you now to get back to porting code over to the board. Here’s the vehicle with its ever growing payload.

Computational Horsepower for Easy Living

Update: Just a word of warning, the distribution of Debian shipped with these board is ANCIENT. Packages are no longer available.

Vehicle Overview and Near Destruction

April 1, 2010 Leave a comment

Just for fun

And some near destruction before proper handling of GPS popping was in place…

Apparently my code has a preconceived need to heard toward fences. Don’t ask me why….

Categories: General, Hardware, Platform, Sensors

Video Done

March 29, 2010 Leave a comment

Complete update. Decided its just easier to host the video(s) here. On that note, here is the video submitted to Sparkfun.

Categories: General Tags: , ,

X-Bee Madness

March 17, 2010 Leave a comment

We’ve using X-Bee modules to send information and commands between the vehicle and a laptop. After we added all the sensor information and other feedback to Proto-2, I started to see communication drop outs when attempting bi-directional comm. Since it is a stop-gap mechanism for test and debug, I wasn’t too worried about it but wow has it been annoying.

The modules are the X-Bee 900 Pro‘s. We had the baud rate ramped up to 115.2 but decided after some calculations to drop back to 38400. No help. So I dug through the manual again. Likely, we should be using API mode but for the moment we kept it simple and just left them in the default broadcast configuration.

The downside of this mode is that the modules are not really communicating point to point even though only two are in the system. So they duplicate broadcast messages to help assure the messages get to everyone in the message. The default duplication is set to 3. I lowered it to 1. If we drop a message here or there, it shouldn’t really effect the performance of the system significantly.

Also, the vehicle is really and end-point, not a router and will never be for this configuration so I changed it to be an end-point not a router. However, that required a firmware upgrade which was seamless using the X-CTU software other than it defaulting the module back to 9600 baud. Honestly both could be set as endpoints I think but I didn’t test that configuration since I was in a rush to get the comm working.

I also tried lowering the packet ratio to zero prior to the other changes to immediately transmit characters rather than bundling messages. It proved too not help but might be a good option at some point. I also lowered the XOFF buffer maximum to 128 characters down from the default of 319 since none of our message strings exceed that length.

If we were going to rely on the radios for good communication, the API interface is the way to go not the transparent default. The changes cleared up the congestion but I made mass changes so cannot specify precisely which one did the trick. If you run into similar issues, I can check the exact configuration and setting changes.

In the end, one more hurdle cleared.

New Link: Geeknight’s Entry

March 16, 2010 2 comments

Geeknight is coming down from Victoria, BC, Canada for the contest. That’s a heck of a commute. Per his post at SparkFun, he’s looking for good lodging options in the Boulder area. If you have suggestions, let him know.

Coming to SparkFun’s AVC?

March 16, 2010 Leave a comment

SparkFun added a spectator registration site to help predict how many people are coming to view the contest. If you are planning to attend, sign on up and put on a Team Hellhound T-shirt. Wait, we don’t have T-Shirts.

Anyway, let the good folks know if you are planning to attend. How many beers you plan on consuming, etc. How hard can it be? Wait, did they ask how many beers?

Anyway, come on out and support all the crazies.

Update: Fixed the borked registration link to point to the proper page.

Bitwise: News and Notes

March 12, 2010 Leave a comment

Today, we added a couple of new Sponsors. Normally, sponsors provide some material or fiscal support. Not us. We flag them sponsors when some company, individual or organization goes out of their way to help us. Every bit of support is useful and these guys step up to the plate regularly.

Battery Buddies gave us some free product and significant technical advice. If you use batteries with Dean’s connectors, these simple additions make your life much simpler. Hopefully one day SparkFun will carry both Deans connectors and Battery Buddies caps.

Next up, the Colorado Rotor Heads has provided a great deal of RC knowledge and expertise. If you already fly RC Helicopters or would like too, this club rocks. The members rank from sheer novices, like Floyd and I, to top-notch pilots who make helicopters do things that seem impossible. Check them out if you are in the area.

Also, a new Cool Company has been added as well. Our competitor and soon to be friend over at Bluer White mentioned the general uselessness of double sided tape for mounting. If double sided tape mounting is a need, take a look at HeliProz’s offering for ZEAL Vibration Absorption tape. Our friend at Battery Buddies turned me onto it. While it seems pricey, the stuff is amazing: great adhesion and provides vibration isolation. I love the stuff. In fact, it sticks so well that it broke the housing loose from a EM-406 GPS receiver when I pulled it off the Traxxas today. Strange they attach a housing with crappy solder joint.