PIC postmortem

hello everybody

i made a PIC18F4550 board which controls 2 motors they are from the AXH series made by oriental motor. the issue is the 4550 died and i cant figure out how this happened

the board was powered from the PICKIT2 , i was trying to run the motors and read the encoder pulses, now controlling motors doesn't take much current at all, and it was running fine for a day.

next day i made some modification to the program and when i tried updating the firmware the PICKIT2 detected my controller as a PIC18F2550
i manually selected the PIC18f4550 from the list and burned the device which completed successfully. when i tried to power the board the PICKIT2 busy LED kept flashing 1~2 Hz i lift up the board to check the connections and i got a nasty burn from the PIC it was hotter than hell and yes it died afterwords

*the board was running fine for over a 2 month. and being powered by either PICKIT2 or USB
*the PICKIT2 survived

here is pin connections

C1,C2 -> PWM from ccp1, ccp2 going to motor1&2 pwm pins
B1,B0 -> EXT INT to capture pulses from the 2 encoders (should i use a series resistor to limit input current ?)

motor 1
D0 -> Start/Stop pin of motor driver
D1 -> Run/Break pin of motor driver
D2 -> CW/CCW pin of motor driver

motor 2
D5 -> Start/Stop pin of motor driver
D3 -> Run/Break pin of motor driver
D3 -> CW/CCW pin of motor driver

the motors require 24V to run i only had 1 battery, 1 ATX PSU so i series them up to get the required 24V but they dont power the board could it be the problem ????

why didnt the PICKIT2 shut off the power before the PIC fried? if i had used a 7805 to pwr the board this wouldnt happen

thanks for your time

What were you using as a motor driver?

the one that came with the motor, ive used it in the past no problems...

schematic?

Any chance to see the circuit? Do you ask the doctor the check your health on the phone? If so, I can imagine the diagnosis... :-0

It seems that somebody asked just ahead of me...