[avr-chat] AVCC / JTAG oddity

[Gary Douglas]

Hi all,

Just got a new board in, and it's behaving strangely.
It's and ATMEGA64 design, but is not usign the A to D.

I've connected AVCC to +5 observing all of the regular precautions 
(bypass cap...).

When AVCC is connected The unit cannot be programmed via JTAG (JTAGICE 
MKII) , and connecting to the unit is spotty.  I can read fuses and 
stuff, but writing doesn't work.

When I cut the track connecting AVCC to +5, the unit works perfectly.

This is contrary to all of the docs, and is quite puzzling.

I have other designs where AVCC is connected to +5 and has NO problems.

The supply looks clean and solid.

Thoughts?

--
Gary Douglas
Manager - Network Products

Pathway Connectivity Inc.
Unit 103, 1439 - 17 Avenue SE
Calgary, Alberta
Canada. T2G 1J9
+1.403.243-8110 x43
www.pathwayconnect.com