I2C between 8MHZ & 16 MHz arduinos

Any issues with doing it? Just wondering. Need to link a FIO and a mega over I2C. Yes I know level conversion will be needed.

(the other end of the xBee link is a FIO & teensy2.0++ pairing..same deal there)

there shouldn't be any issues

level conversion will not be needed, just disable internal pull-up resistors and use external pull-up resistors that "pull" to 3.3V

frank26080115: there shouldn't be any issues

level conversion will not be needed, just disable internal pull-up resistors and use external pull-up resistors that "pull" to 3.3V

So the 5V signals coming from the 5V board won't overdrive the 3V3 pins?

magnethead794: So the 5V signals coming from the 5V board won't overdrive the 3V3 pins?

That's why you use external pull-up resistors.

Doesn’t make sense to me, but I’ll go with it.

Research "open collector".

The I2C pins are open-collector. They need to be pulled-up so if you external resistors and pull them up to 3.3V they become 3.3V pins.

[quote author=James C4S link=topic=121012.msg910722#msg910722 date=1346471678] Research "open collector".

The I2C pins are open-collector. They need to be pulled-up so if you external resistors and pull them up to 3.3V they become 3.3V pins.

[/quote]

works for me.