# Internal Communication Lines
The device is equipped with multiple internal communication lines of the following types:
- [{{@134#bkmrk-spi}}](https://doc.redisage.com/link/134#bkmrk-spi)
- [{{@134#bkmrk-i2c}}](https://doc.redisage.com/link/134#bkmrk-i2c)
- [{{@134#bkmrk-uart}}](https://doc.redisage.com/link/134#bkmrk-uart)
### SPI
The device is equipped with the following SPI communication lines.
#### SPI1
| **Signal**
| **Processor pin**
| **Default function**
|
| Chip select 0
| AD18
| SPI1\_CS0
|
| Chip select 1
| AG23
| SPI1\_CS1
|
| Master in slave out
| A7
| SPI1\_MISO
|
| Clock
| D6
| SPI1\_SCLK
|
| Master out slave in
| B7
| SPI1\_MOSI
|
#### SPI2
| **Signal**
| **Processor pin**
| **Default function**
|
| Chip select 0
| A6
| SPI2\_CS0
|
| Chip select 1
| AF12
| SPI2\_CS1
|
| Chip select 2
| AB19
| SPI2\_CS2
|
| Master in slave out
| A8
| SPI2\_MISO
|
| Clock
| E6
| SPI2\_SCLK
|
| Master out slave in
| B8
| SPI2\_MOSI
|
### I2C
The device is equipped with the following I2C communication lines.
#### I2C2
Device name: **/dev/i2c-1**
| **Signal**
| **Processor pin**
| **Default function**
|
| Clock
| D10
| I2C2\_SCL
|
| Data
| D9
| I2C2\_SDA
|
#### I2C3
Device name: **/dev/i2c-2**
| **Signal**
| **Processor pin**
| **Default function**
|
| Clock
| E10
| I2C3\_SCL
|
| Data
| F10
| I2C3\_SDA
|
#### I2C4
Device name: **/dev/i2c-3**
| **Signal**
| **Processor pin**
| **Default function**
|
| Clock
| D13
| I2C4\_SCL
|
| Data
| E13
| I2C4\_SDA
|
### UART
The device is equipped with the following UART communication lines.
#### UART1
Device name: **/dev/ttymxc0**
| **Signal**
| **Processor pin**
| **Default function**
|
| Receive (UART1 RX)
| E14
| UART1\_RXD
|
| Transmit (UART1 TX)
| F13
| UART1\_TXD
|
#### UART2
Device name: **/dev/ttymxc1**
| **Signal**
| **Processor pin**
| **Default function**
|
| Receive (UART2 RX)
| X
| UART2\_RXD
|
| Transmit (UART2 TX)
| X
| UART2\_TXD
|
#### UART3
Device name: **/dev/ttymxc2**
| **Signal**
| **Processor pin**
| **Default function**
|
| Receive (UART3 RX)
| E18
| UART3\_RXD
|
| Transmit (UART3 TX)
| D18
| UART3\_TXD
|
#### UART4
Device name: **/dev/ttymxc3**
| **Signal**
| **Processor pin**
| **Default function**
|
| Receive (UART4 RX)
| F19
| UART4\_RXD
|
| Transmit (UART4 TX)
| F18
| UART4\_TXD
|