I have a custom board designed with a Mega16U that I am trying to bring up. Using the squid cable on the ICE, I wired up TCK/TMS/TDI/TDO and VCC and GND (two grounds). When I try to read the device voltage in Studio, it's jumping between ~2.5V and 3V. But my DMM says it's a steady 5.1V. I then noticed that if I disconnect TDO, the voltage reading drops to 0V. Does the ICE use the data lines somehow to try and measure voltage? I'd expect that with just VCC and both grounds hooked up I should be able to read the voltage, but no. Is my ICE hosed?
Joined: Mon. Mar 17, 2008
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