AVR-Chat

Ok, I broke down and checked the STK500 schematic. The six pin ISP header, J906, is
connected as follows:

	1 - MISOT  (O.C. output with 1K pullup)
	2 - VTG    (hardwired, no jumper)
	3 - SCKT   (O.C. output with 1K pullup)
	4 - MOSIT  (emitter of common-base Q901B with 47K pullup)
	5 - /PROGRST
	6 - GND

So power is no problem, it's whatever you have the board set to.

Then I tracked down what was driving /PROGRST. It has the collector of Q203B pulling it down
along with a 22K resistor R208 to GND. The only pullup is Q201A and it's is only active when
doing high voltage parallel programming; it pulls the line up to +12v. So it looks like a 4.7K
or so pullup is needed on the reset line.

Bruce


Daniel Boyer wrote:
> 
> 
> > Pin-18 (AVCC) is floating; it needs to be connected to the
> > supply. And at least one .1 mfd
> > cap between the supply and ground for bypass.
> 
> Didn't reallized that AVCC had to be connected if I wasn't using the
> Analog circuty...maybe this is my problem...Thats a quick and easy fix
> that I'll try right now.
> 
> Daniel