====== Expansion header pinout ======

**Bold** = Default configuration, can be changed via solder jumpers

^ Signal ^ Pin Nr. ^ Pin Nr. ^ Signal ^
| 3.3 V | 1 | 2 | 5 V |
| **Jetson I2C 0 SDA**, SMARC I2C GP SDA, SMARC GPIO 1 | 3 | 4 | 5 V |
| **Jetson I2C 0 SCL**, SMARC I2C GP SCL, SMARC GPIO 0 | 5 | 6 | GND |
| SMARC GPIO 2 | 7 | 8 | **Jetson UART 0 TXD**, SMARC UART 1 TXD |
| GND | 9 | 10 |  **Jetson UART 0 RXD**, SMARC UART 1 RXD, Jetson GPIO 0 |
| **Jetson UART 0 RTS**, SMARC UART 1 RTS, SMARC GPIO 3 | 11 | 12 | **Jetson I2S SCLK**, SMARC I2S SCLK, Jetson GPIO 2 |
| SMARC GPIO 4 | 13 | 14 | GND |
| SMARC GPIO 8 | 15 | 16 | Jetson GPIO 3 |
| 3.3 V | 17 | 18 | Jetson GPIO 5 |
| **Jetson SPI 0 MOSI**, SMARC SPI 0 MOSI | 19 | 20 | GND |
| **Jetson SPI 0 MISO**, SMARC SPI 0 MISO | 21 | 22 | Jetson GPIO 6 |
| **Jetson SPI 0 SCK**, SMARC SPI 0 SCK | 23 | 24 | **Jetson SPI 0 CS0**, SMARC SPI 0 CS0, Jetson GPIO 9 |
| GND | 25 | 26 | **Jetson SPI 0 CS1**, Jetson GPIO 10 |
| SMARC GPIO 9 | 27 | 28 | Jetson GPIO 11 |
| SMARC GPIO 10 | 29 | 30 | GND |
| SMARC GPIO 11 | 31 | 32 | Jetson GPIO 13 |
| SMARC GPIO 12 | 33 | 34 | GND |
| **Jetson I2S FS**, SMARC I2S FS | 35 | 36 | **Jetson UART 0 CTS**, SMARC UART 1 CTS, Jetson GPIO 12 |
| SMARC GPIO 13 | 37 | 38 | **Jetson I2S DIN**, SMARC I2S DIN |
| GND | 39 | 40 | **Jetson I2S DOUT**, SMARC I2S DOUT |