It’s a runaway succ…. failure

Another failure! Though all signs pointed to it working…

So I got a freebie OddBot sent to me a couple of weeks ago, it basically is a derivative of my Mecanum Rover and Olaf was kind enough to sent it with almost everything attached less the Chumby. Since I’ve been on a TI Launchpad buying spree, I thought I’ll tack one on in place of the Chumby to drive it.

So far this post reads like a gigantic spam with all those links…no enlargement links coming up, I promise…just one short video of it not working and running away on me.

So I figured, how hard can it be? I procrastinated soldering 2 header pins onto the Launchpad’s TP1 and TP3 tie points for power but after doing that everything was almost recycling :-

Code – Copied from Madox Kart prototype code and original Rover code…took around 15-30 minutes to copy/paste and tidy up some comments.
Carrier for Launchpad + Battery + Breadboard – Almost a direct copy of the Madox Kart prototype again… 15minutes to tweak and 1+ hour to print. [Ok 3+ hours, 1+ hour on 0.4mm layers but 3+ hours on 0.2mm layers which I’m a sucker for].

Everything seemed ‘too easy’ so far, even the code compiled first time which I didn’t believe. Then the problems started mounting…

Problem 1 – Cheap mini-USB cables from eBay failed to connect to the Launchpad properly. Cable 1 was a complete no go (marked for butchering into a power cable), cable 2 worked only if the connector was held at a particular angle. I programmed the Launchpad while keeping my hand steady holding the cable. Cheap eBay USB cables, you disappoint me yet again.

Problem 2 – Connected everything up onto the breadboard and all, no blinky lights on the Launchpad!!! Head scratch for a total of ~30 seconds. It turns out it is the age old problem of ‘slightly too fat’ AA cells. The AA cells are just a bit too wide for the battery holder and because of such, the friction between batteries was stronger than the spring and the + terminal wasn’t making contact. Don’t know whether to blame this on the battery holder or the batteries…

Problem 3 – Continuous rotation servos were not zero’ed, and they were a pain to do so, the slightest adjustment movement will have it spinning the other way. 2 minutes later the zero’ing seems to have been gone, probably due to temperature drift (heating up) – PITA.

Problem 4 – My favorite – it didn’t work. Initially because I didn’t pair the Wii Nunchuk (Duh! moment) and then probably down to the hackity software code 🙂 The movement matrices seemed wrong and the servo control was very odd, need to debug that later. Highlight – IT RAN AWAY ON ME. Best illustrated in video form :-