Input/Output
Additional information on which pins can be used for which functions is available on the pin information page.
Gen 3 Devices (Tracker SoM, Tracker One):
The Tracker SoM has shared A and D pins. In other words, pin A0 is the same physical pin as pin D0, and is also the SDA pin. The alternate naming is to simplify porting code from other device types.
| Pin | M8 Pin | Function | Function | Analog In | GPIO |
|---|---|---|---|---|---|
| A0 / D0 | Wire SDA | ✓ | ✓ | ||
| A1 / D1 | Wire SCL | ✓ | ✓ | ||
| A2 / D2 | Serial1 CTS | ✓ | ✓ | ||
| A3 / D3 | 3 | Serial1 RTS | ✓ | ✓ | |
| A4 / D4 | SPI MOSI | ✓ | ✓ | ||
| A5 / D5 | SPI MISO | ✓ | ✓ | ||
| A6 / D6 | SPI SCK | ✓ | ✓ | ||
| A7 / D7 | SPI SS | WKP | ✓ | ✓ | |
| TX / D8 | 5 | Serial1 TX | Wire3 SCL | ✓ | |
| RX / D9 | 4 | Serial1 RX | Wire3 SDA | ✓ |
On the Tracker One and Tracker Carrier Board you must enable CAN_5V in order to use GPIO on M8 pins 3, 4, and 5 (A3, D8/TX/SCL, D9/RX/SDA). If CAN_5V is not powered, these pins are isolated from the MCU starting with version 1.1 of the Tracker One/Tracker Carrier Board (September 2020 and later). This is necessary to prevent an issue with shipping mode, see technical advisory note TAN002.
P2 and Photon 2 Devices:
On the P2 and Photon 2 in addition to the standard analog inputs A0, A1, A2, and A5, there are two shared pins. If you are not using pins D0 and D1 for I2C or digital GPIO, they can be used as ADC inputs:
| Pin | M8 Pin | Function | Function | Analog In | GPIO |
|---|---|---|---|---|---|
| D0 / A3 | Wire SDA | ✓ | ✓ | ||
| D1 / A4 | Wire SCL | ✓ | ✓ |