This is a fairly simple project: connect the application-specific I/O pins on the Feather to connectors that can make use of those applications. These consist of:
- An SPI connector similar to those on full-sized Arduinos
- Two Qwiic connectors for the I2C bus
- A 3-pin Picoblade connector to utilize the RX/TX pins
Since the Feather doesn't really have a 5V pin for the SPI, a voltage converter (the Maxim MAX619) is included to provide the needed voltage. (Note that the converter is rated at 50mA, so don't overload it!)
If you use more than one of these, remember that the RX/TX connection is a two-way communication; only hook up one other device to this, no matter how many GateWings you have! In fact, the Picoblade connector is meant only to communicate with another Feather with a GateWing, or an Arduino Mega (or Adafruit Grand Central) with the Grand Central Connector Union Station Shield (qv). For anything that doesn't have its own power supply, a 4-pin UART connector would be better.