• Registered: 2010-03-04
  • Posts: 5

Topic: Serial port voltage

I want to connect my Chumby one to an AVR-based microprocessor system via the serial port. The AVR system runs at 5V. Can the Chumby serial Rx accept 5V input, or do I need to build some intermediate circuitry. And if I do, would a simple resistor be adequate?

  • Registered: 2011-02-07
  • Posts: 24

Re: Serial port voltage

I'm not sure if the Chumby is 5v tolerant, but I'm guessing it's not. You might be able to get away with a voltage divider from AVR TX to Chumb RX if the AVR accepts 3.3v as logic high.

To be on the safe(and easy) side, you can just get one of these guys:
http://www.sparkfun.com/products/8745

  • Madox
  • Busy Chum
  • Offline
  • From: Sydney
  • Registered: 2008-04-12
  • Posts: 121

Re: Serial port voltage

3.3V, not 5V tolerant.

Why not consider running the AVR at 3.3V?

Actually I would use a USB->Serial converter and leave the serial console alone wink
[The serial port is the default console port]

Madox's Website

  • Registered: 2010-03-04
  • Posts: 5

Re: Serial port voltage

Thanks for the replies.

I've tried USB to serial, but find I'm losing data input to the Chumby. (I've also found this on my laptop running XP).

The AVR system is already built with 5V components, so I'll go with a divider