I was hoping someone could tell me why I am having spotty communication with my I2C bus on various PIC MCUs. I've tried using a 16F887 and a 877 and sometimes they will connect to my INA209s on the I2C bus, and sometimes they won't. The circuit and code do not change but the PIC and the INA209s refuse to talk to each other. I have the 16F887 on a demo board with the SCL and SDA wires running to a breadboard where I have the INA209s. The SCL and SDA lines are pulled up to 5V using 4.7K resistors. I had the same issue yesterday that I fixed (and I am completely serious about this) by straightening the wires and connecting to a scope. Since that remedy is not working today, could there be another type of voodoo that I can try to get these two devices to play nicely?