Love to get technical.
Alex, you are connecting to Particle P1. Here is the pinout of the extension port:
Re. Extension port:
- I2C SCL
- I2C SDA
- +5V
- GND
I2C pins can also be used as GPIO pins D0 and D1.
| 35 | MICRO_I2C1_SCL | PB6 | D1 (I2C SCL) |
|---|---|---|---|
| 36 | MICRO_I2C1_SDA | PB7 | D0 (I2C SDA) |
You can see this is done in the modified firmware version where one of them is used for hardwired contact sensor.
More questions? AMA!