Pololu Robotics & Electronics
My account Comments or questions? About Pololu Contact Ordering information Distributors

Pololu Forum

Using Arduino Uno's SPI protocol over the wixel shield

The wixel shield does an incredible job of programming my arduino uno and transferring data over the serial monitor wirelessly. However, one my sensors communicates over SPI protocol and it has trouble initializing when connected over the wixel shield. It works fine when I connect it directly to the Uno. The sensor is the bitcraze PMW3901 optical flow unit which uses Uno GPIO pins 11-13 for SPI communication. Why there is a conflict of SPI comms over the wixel shield? Is there is a work around to operate my sensor over SPI using the wixel shield? Also, I am considering clipping pins 11-13 on the shield so that I can wire the Uno’s SPI pins directly to my sensor. will this impact the operations of the shield itself?

After going through the datasheet/user manual for the shield, it seems like the problem is that pin 13(SCK pin for SPI comm) is used by the shield for the user LED on the shield. So I wonder if there is some way to deactivate the LED or switch the LED pin to another one.


You can disconnect the LED by cutting the trace on the board between pin 13 and the LED. The trace is fairly exposed and does not have much around it at the indicated spot the picture below:

If that does not fix the problem, can you post close-up pictures of both sides of your Wixel shield?


That’s an interesting solution. Thanks for your response. I ended up bending pin 13 on the shield and plugged sensor’s SCK pin directly to the UNO and it works quite well.