I've been fooling around trying to drive a small robot using a wireless wii nunchuck. It took me a while, but scouring these forums i found code by Mike T, MadMax11, XenonJohn and others which with a bit of manipulation i got to work. I'm using Duemilanove with an ardumoto shield and a wiichuck adaptor from todbot.
When i say work, i mean i got to read the i2C from the nunchuck and serial print it. When i went to use the code to drive my robot, i attached my motor shield and plugged in its own power supply (7.4V battery - i'd discovered with previous version using wired chuck that the motors would only work with an independent power supply to the ardumoto) The moment i attached the battery the trace smoked.
I thought there must have been a short from the leg of one of the 1.8K pullup resistors i had between pins 4 and 5 and +5V. I soldered in a jumper across the burnt trace and trimmed the resistor legs so they couldn't touch anything, and tried again. The moment i attached the battery another length of trace, just up from where i had attached the jumper, went up in smoke.
The code i'm using to connect the chuck sends power to pins 2 & 3:
#ifdef POWER_VIA_PORT_C2_C3 // power supply of the Nunchuck via port C2 and C3
PORTC &=~ _BV(PORTC2);
PORTC |= _BV(PORTC3);
DDRC |= _BV(PORTC2) | _BV(PORTC3); // make outputs
delay(100); // wait for things to stabilize
I'm wondering, is there any chance this could be interfering with the ardumoto shield and causing a short? Is there any known issues which would cause the motor shield to fry? I'm stumped, and i don't want to burn any more boards!
Thanks in advance for your responses,