We are experimenting a strange and dangerous behavior on a FEZ-Cobra-based device.
We have some IOs connected to a relay board (similar to this one:http://www.sigma-shop.com/product/13/eight-relay-board-ready-for-your-pic-avr-project-12v.html).
Whenever we bootup our board, such IOs turn on relay coils, making, for example, 220V engines connected move! After boot, our firmware sets such IOs as output and pulls them low, turning off motors.
Note that connecting motors to NC instead of NO (or viceversa) dosn’t solve the problem, since de-powering control device turns on motors again!
P.S. I know that IO pins should boot in input (high impedance) mode, but it seems that this is not enough to keep colis unenergized. Please note that unconnecting IOs from relay board, relay colis turn off (so high impedance and unconnected scenarios don’t show same behavior)