I've got an interesting occurrence on I2C, looking for any advice on things to try to remedy it.
I've built a custom arduino clone. It uses a 16U2 for the serial interface and 328PB for the main chip. It works fine during basic operation (blinking LEDs, etc), but when I try to use I2C, the SDA and SCL lines output a never ending stream of data. It doesn't matter what I2C library I use (Wire.h/I2C.h). It doesn't matter what function I perform. It seems the minute I call wire.beginTransmission() or I2C.begin(), the ports just send out never ending data. The transmissions don't cease even when calling Wire.endTransmission()/I2C.end().
I'm trying to connect to a PCA9673 and a PCU9656. Doesn't matter if both or one is on the I2C line. It doesn't matter what pullup resistor values I use. Data shape is very clean. My sketch is down to a few lines of code to debug, nothing else going on.
Thoughts? Anyone ever seen this type of behavior from the I2C libraries?