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Pixy/ Arduino pins HIGH

Pixy Software
#1

Colleagues:

I have found that any Pixy sketch that I upload to an UNO is setting digital output pins 10, 11 & 13 HIGH even if they are not called in the sketch. If I upload any of my other (non-Pixy) sketches, this does not happen and it happens irrespective of whether the Pixy camera is plugged into the Arduino, or if the camera is plugged into the computer USB. It seems to be an issue in all Pixy sketches, even “Hello World.”

Is this an anomaly in one of the libraries or am I over looking something?

Thanks in advance,
FR Prete

#2

FOLLOW up:

If I switch to analog A0-A3 pins and use them as the last four digital outputs (instead of digital output pins 10-13), the sketch runs as it should.

#3

Hello Frederick,
This makes sense because the Pixy demos use the SPI port to communicate (including hello_world). Pixy uses the Arduino ICSP port, but the SPI pins in the ICSP port are also routed to pins 10, 12, 13, 14 in the UNO (different pins depending on the Arduino version).

It’s recommended that you use non-SPI pins for I/O (if you can). Or you can use I2C or UART communications with Pixy. (however, I2C and UART require you to make your own communication cable to talk to Pixy.)

Edward