RFduino port expander
We have created a port expander for the RFduino, with the eventual goal of adding 8 more I/O's to the RFduino. We selected the MCP23008 because Adafruit has an Arduino library for it, but it turns out that the library isn't directly comparable with RFduino. I am sure the changes required are minor but I decided to do a simple tutorial on writing to this port expander directly!
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