Just to be fair, it appears that the serial problems that I was having with the ZigBit module was in part due to the USART mode on my BusPirate.
I was having all kinds of problems running 38400 baud on the 8Mhz RC clock - when I stumbled on the clock variance I figured it was that. I later hooked up a FTDI cable to the serial out on the same ZigBit and got really good communications at 38400b.
It was "Really Good" but not quite "perfect" I was still able to hit the ZigBit with freeze spray and cause problems with the output:
Hello, world 43
Hello, world 44
Hello, world 45
Hello, world 46
Hello, world 47
Hel wor 48
Hellorld 49
Hello, world 50
Hello, world 51
lo, world 52
Hello, world 53
ello, world 54
Hello, world 55
Hello, world 56
Hello, world 57
I was able to drop the clock speed (using fuses) to 1Mhz and run 9600 baud when I used the double speed mode for the USART, but then the module is running pretty slow. That may be OK for what I need - And 9600 baud may work "perfectly" when running the 8Mhz RC clock, even with the variance.
Also, there wasn't much need for all of the PWM stuff I did two posts ago - you can set the CKOUT fuse and get clock output on pin 42 of the ZigBit module.
