I have both AVRISP mkII and the Pololu ISP programmer and both are exhibiting the same behavior. Both tools say the target voltage drops when trying any programming operation, like reading the device id.
I put a scope on the ISP VDD pin and there is no change. +5 volts all the time.
It clearly isn’t either of the tools - they are both doing exactly the same thing. It isn’t the target device power supply: I have both an external supply and the AVR ISP is rigged to supply USB power to the target with a switch. Both USB power and the external supply do exactly the same thing.
It isn’t the ISP frequency - I can set anything I like and it has no effect whatsoever. This is happening on two computers, one with AVR Studio 4 and one with AVR Studio 6.
My target board has been used for 10-15 different chips, each programmed fine until one day about a month ago. I have no idea what might have happened. Fresh chips, straight from the tube they came in make no difference.
Any suggestions on what to look for with this?