Well..., I'm beginning to doubt my sanity. A very simple deal:
DDRC = 0xFF;
PORTC = 0;
port_val = PINC;
And yet..., and yet, bits 4&5 (port_val) *refuse* to be read as zero! No TWI(which uses those bits)stuff going on to befoul things. I'm stumped...slightly suspicious that that the SCL/SDA are involved, but should not be. I've also tried defining DDRC as 0x00, *grounded* those pins and PINC bits 4&5 remain at '1' state. I figured it must be a blown chip, plugged in another..., same deal. This is true both on STK500, and a stand-alone board, which has *nothing* tied to those pins. At a loss, and under pressure... Have I overlooked something obvious?? Some fuse thing? Helppppp!