AVR-P28 Board Design Error (3.3V)

Development Boards MicroMod
1

Hello,

I am trying to use the AVR-P28 board at 3.3V, and my AVR-ISPmkII kept throwing errors. I checked all the wires and everything, even went to 5V for a while.

Well, of course it works on 5V.

U3, the ZM33064 is causing a reset condition at 3.3V (its threshold is 4.6V). I think the inclusion of that IC on a board designed for dual 3.3V/5V operation is a mistake.

For all the other forum users wondering why 3.3V mode doesn’t work, try removing U3. It seems after I did that that the AVR ISPmkII seems to like the AVR-P28 board at 3.3V.

2

In the [user manual, read the warnings at the bottom of the “Hardware” section.](http://www.olimex.com/dev/pdf/AVR-P28.chm)