> I thought week pull-ups only worked if pins where configured as inputs?

In order to properly communicate with an I2C device, you need to switch
between input and output on at least the SDA pin, and if you want to fully
implement the standard, the SCL pin, too.

In fact, the implementations of the I2C I've seen from Scenix always
configure the weak pull-ups on both SCA and SCL, and only configure the pins
for output when they're driving the line low.  All other times, the pins are
configured as input, and the weak pull-ups pull the line high.

You shouldn't configure the pins as outputs when outputting a 1 since you
potentially conflict with another device trying to simultaneously hold the
data line low.

What is the other device on the I2C bus?

-- Mitch

Mitch Miller, Omaha, NE
mdmiller2@home.com