I am trying to power a Pixy2 with an external 6Vdc supply and communicate to the Pixy2 over I2C. Pin 5 is going to I2C SCL on the controller, Pin 6 is going to Gnd on the controller, and Pin 9 is going to I2C SDA on the controller. Pin 10 is going to the 6Vdc supply. The question is where do I connect the ground for the 6Vdc supply.
Connect the ground (negative) of your supply to pin 6 (GND) and positive to pin 10 (as you indicated). See the diagram here:
Thanks for the response. I was assuming since I am using I2C for Comms that I needed to connect the Pin 6 ground to the controller that I am connecting Pin 5 (I2C SCL) and Pin 9 (I2C SDA). Do I connect pin 6 to ground on the power supply AND the controller?
That is correct – use GND (pin 6) for both the power and the communications.