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Pixy LED is on when its not supposed to be. Busted diodes?

Pixy Hardware
#1

Hey guys!

Im powering my pixy via USB port. Simply put, I cut usb wire and hooked up 5V to the arduino 5V pin, and hooked up GND to arduino via MOSFET transistor.
Using a transistor, I can turn pixy on and off, no problem.
Interesting things happen when I also connect I2C wires to pins 5 and 9. When I turn transistor OFF, I expect pixy to turn off as before, but thats not what happens.
Red LED on pixy stays on.

I looked at the circuit diagram provided in the documents section and dont really understand whats going on. Are my D7 diodes busted? (I observe this on 2 pixy cams)
Is RED_LED gate set high whenever I2C is used? How much current approximately can I theoretically expect to lose if I connect only +5 volts (no ground) to pixy and wire up I2C?

Thank you!

Vadim.

#2

Hi Vadim,

Basically, you’re powering Pixy through the I2C port, but only enough to light the led. That is, the I2C port will sink current into the Pixy power rails if Pixy isn’t powered up. It’s a common phenomenon and not restricted to I2C.

Scott