If you are using SPI programming mode you shoud tie this pin to the ground. When /PEN is low, chip will enter SPI programming mode during reset. /PEN has no function during normal operation. Although I'm using JTAG programming mode, I'm keeping /PEN tied to Vcc anyways, via 10K resisitor. -- D.G.
Message
Re: /PEN pin on ATMEGA128
2004-12-12 by DG (dee-gee)