ATMEGA328 and ATMEG8U2 Schematic on the Arduino Uno Rev 3

I am looking for the schematic for the Atmel Chips on the Arduino Uno. I am unsure if I should contact an Atmel Rep but I figured I start here in this forum.

I'd like to know what the chip has internally but I also have a unique problem I am trying to solve.

I have an AC wave form that has been rectified to +/- 2.5v square wave and I want to put this into one of the analog inputs of the chip. I am using the square wave to control a Digital output.

Datasheets for the devices can be found here

Basically, you can input a 0 to 5V signal only. -2.5V is a big no-no.
If it's a 0-5V square wave, you can feed it into a digital pin and use it for interrupts, pulseIn() measurements, etc. and go from there.

Thank you so much!

I was wondering if -2.5v was bad, thanks for letting me know.

Appreciate the link.

Regards,
JP :slight_smile: