Well, the Bluetooth USB module never did show up from eBay. :-( The seller was great, though, and gave a full refund... however I am still stuck without a Bluetooth module and without time to order another one from eBay. I guess I will have to troll the local computer stores for an overpriced one that works with Linux...
In the mean time, I have been re-working the control board which will hopefully allow for some improvements. The (not yet finalized) revision 2 board is below:
Some improvements over the rev1 hardware include:
- Breakaway adaptors for both XBee and Bluetooth radios, so there is no need to buy the Sparkfun XBee adaptor
- A more standard pinout for the serial connection: rather than using the 10 pin XBee connection (adapted from 2mm to 100mil spacing), I now use the 6 pin FTDI pinout (and include a jumper to configure whether the serial port is powered at 5v or 3.3v). This saves some board space, and would simplify debugging as I can simply plug in a cable rather than messing about with RF modules.
- 5v boost regulator (input from a heavily filtered the 3.3v linear regulator) will allow for 20MHz operation (vs. 12 MHz operation in rev1), as well as allowing for 5v peripherals (most notably the ultrasonic range finders)
- A bit of space between each leg's servo connectors (they all fit on the rev1 board, but it gets tight)
- Board space for additional capacitors on both servo power supply rails as well as the 5v and 3.3v rails (vs. nothing on rev1, and haphazardly placed components on the semi-official rev1.1)
Some disadvantages include:
- More surface mount components, and at a finer pitch than rev1. I soldered the rev1 board with a pretty normal iron; I would not attempt this with rev2. Solder paste is pretty much required (44-TQFP, 0603, etc)
- A few more components required (most notably the 5v boost regulator with associated hardware). However the savings from not buying a Sparkfun XBee board should compensate for this.
- It will take another month for me to get it, starting from the point at which I have finalized the design and have ordered it from DirtyPCBs :-(