I2C between 8MHZ & 16 MHz arduinos

[magnethead794]

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)

[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

[magnethead794]

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?

[cmiyc]

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

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

[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.

[cmiyc]

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.

[magnethead794]

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.

works for me.