• GPIO16 – Default button (or CLK for APA102)
• GPIO17 – Default LED out (DI for APA102 strip)
• GPIO18 – IR receiver or optional button
• GPIO19 – Relay
• GPIO23 – Dallas temperature sensor (optional – used to report over MQTT temperature on board)
•G PIO22 – I2C SCL
• GPIO21 – I2C SDA
• GPIO36 – Analog input for microphone or another analog device.