External voltage to STK500...

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#1
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I'm trying to power everything off my 3V battery pack including the mega48 sitting on the STK500.

To do so, I disconnect the VTARGET jumper on the STK500 and put 3V from my battery pack on the VTG pin of one of the port headers. I also attach the negative side of the battery pack to one of the GND pins of the STK500.

In this configuration, the circuit doesn't turn on.

If I plug in the regular power supply to the STK500 (but change nothing else - VTARGET is still disconnected) it all works.

I'm not sure why I have to power the STK500 control chips in order to get the mega48 to run. The mega48 is using its internal oscillator.

Anyone know what I'm missing?

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What's connected to the RESET pin of the chip - could the quiescent STK500 circuitry be holding it in reset?

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That did it! I disconnected the reset jumper and attached vtg to the side of the jumper closest to the sockets.

Appreciate it.