I broke down and ordered an Arduino (ok, the Freeduino SB, specifically) from HVW Tech. Piece of advice – to save on the $5 handling fee “on orders under $30″ — add an L293D motor driver for to your order for $3.95. You know you’re gonna need one anyway… ;)
So, I ordered a PICAXE 28X1 board from Advanced Micro Circuits (aka World Educational Services), and it arrived yesterday. It’s a bit smaller than I expected (which isn’t a bad thing at all!), but it was also sans-interface cable, which was a bit of a let down (the cable is, however, en route!). Either way, it’s a compact microcontroller package with a decent feature set, so I’m looking forward to playing with it. Fits inside an altoids tin, sans-batteries, and I suspect with a proper LiIon pack, it’d probably fit in the tin with batteries. We’ll see… :)
It was up against the Freeduino SB (produced by Solarbotics / HVWTech, a derivative of the Arduino Deicimila board), which probably would have been my choice had I done some more research up front. The Freeduino SB is a bit cheaper, mostly due to the fact that it ships as a semi-kit where only the SMT components are pre-soldered, and the rest of the assembly is up to the purchaser, but the trade-off was that the PICAXE was built with the capability to add a motor driver by simply socketing an L293 into a slot on the PICAXE board — the Arduino would require an external circuit. What I didn’t know, was that Adafruit sells a motor driver “shield” for the Arduino for just under $20.
Finished assembling the Sumovore today. All in all, I’m not sure what to make of it – the kit has some nice features, but doesn’t have the same sort of “solid” feel that the MarkIII does. Give and take, I suppose. The MarkIII, when it’s done, feels a bit more professional, but the Sumovore at least came with documentation! Caveat, the docs were a little off in a couple of places – particularly when telling you to place Resistor R27 on the discrete brainboard – apparently at some point one of the resistors was replaced with a diode, so there’s “eight (not 8, not 10, but 9!)” diodes to be installed, and the resistor destined for R27 (“completely ignoring R26″) actually goes in R26. And yes, there are indeed nine diodes.
Other than the small mishap with the docs, assembly is pretty straightforward – a lot of little components but nothing overly complicated or unusual. There are a few areas where I was left to wonder why the specific installation order had been chosen, and almost certainly there are a couple of items which should be handled differently, but on the whole it was easy going.
Once assembled, it’s a matter of tweaking potentiometers to get the ‘bot to function optimally; there’s one each for the left and right pair of edge sensors, one for the forward facing IR sensors, two to tweak motor behavior, and one to adjust the startup delay.
I’ll move on to the BS2 brainboard sometime in the next couple of weeks; I’ve got some projects that need attention, but I’ve been stuck at a plateau on one of them and needed to distract myself for a little while to clear my mind.