Hi
Here is a brief run down of my problem:
I have been using an ICD-2 to In-circuit-serial-program a 18f4620. I have attached a cutout of the relevant part of the circuit.
The target circuit is powered from its own supply, therefore the ICD-2 is simply powered from the USB port (no DC power supply connected). In MPLAB, the setting to power the target from the ICD-2 has been disabled.
Now the problem I am having is that somehow, every now and then (with no particular change in procedure) the PIC gets completely destroyed when I try and program it. I start with power to the target board turned on, then plug in the ICD-2 ICSP connector onto the board, then try and connect to the ICD-2 in MPLAB, only to get the response "ICDWarn0020: Invalid target device id (expected=0x60, read=0x0)", ie the PIC is not responding.
Usually this procedure works and I can happily program the PIC, but on a fairly regular basis I end up with a non-responsive pic which has to be replaced. By non-responsive I mean it does nothing, starts up but you can't talk to it on rs-232, can't talk to it with the ICD2 in ICSP mode, does not respond to stimili on the ports, nothing.
I cannot see any obvious way in which the pic can be damaged in this circuit. Could anyone please give their opinion/advice if they have had a similar problem?
Thanks a lot.
Here is a brief run down of my problem:
I have been using an ICD-2 to In-circuit-serial-program a 18f4620. I have attached a cutout of the relevant part of the circuit.
The target circuit is powered from its own supply, therefore the ICD-2 is simply powered from the USB port (no DC power supply connected). In MPLAB, the setting to power the target from the ICD-2 has been disabled.
Now the problem I am having is that somehow, every now and then (with no particular change in procedure) the PIC gets completely destroyed when I try and program it. I start with power to the target board turned on, then plug in the ICD-2 ICSP connector onto the board, then try and connect to the ICD-2 in MPLAB, only to get the response "ICDWarn0020: Invalid target device id (expected=0x60, read=0x0)", ie the PIC is not responding.
Usually this procedure works and I can happily program the PIC, but on a fairly regular basis I end up with a non-responsive pic which has to be replaced. By non-responsive I mean it does nothing, starts up but you can't talk to it on rs-232, can't talk to it with the ICD2 in ICSP mode, does not respond to stimili on the ports, nothing.
I cannot see any obvious way in which the pic can be damaged in this circuit. Could anyone please give their opinion/advice if they have had a similar problem?
Thanks a lot.