Hope you can help me out with this one:
In three different STK500 boards I have been unable to read the signature byte from the attached MCU. Fuses and flash programming are also not available. I've used different MCUs and even my own board connected to the ISP6PIN header. I've tried with two different RS232 cables and with a restart of the computer. What does work, however, is reading and writing the STK500 voltages.
If I set the voltages to 5V and then read signature, it enters programming mode and reads a signature equal to 0xFF 0xFF 0xFF. Different boards to this with different chips. I believe the ISP6PIN cable is connected correctly.
Setting the voltages to 3.3V, it is not able to enter programming mode, even with an atmega16L.
I use version 4.11, build 401 of AVRStudio. My power supply is 9.4VDC into the rectifier with the STK500 board on. Any ideas why this fails repeatedly?