Strange ISP programming error

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?


I am sorry you are having trouble programming your AVRs.

For now, I recommend using the Pololu USB AVR Programmer Configuration Utility (found in your start menu) to set the ISP frequency to 200 kHz, which is the default frequency and should work for most AVRs.

I wasn’t aware that the AVRISP mkII was able to report details like that. Could you elaborate on how you got that information from the AVRISP mkII? What exact error message did you see?

Our USB AVR Programmer actually reports the range of voltages it encountered during programming. After a failed programming attempt, could you run the Pololu USB AVR Programmer Configuration Utility and tell us what voltages it is reporting? Also, what error is it reporting under “Error From Last Programming” ?

I hope you are being careful not to short the external power supply to the USB power supply by turning them both on at the same time.