| Name | Description | Type | Active Level |
|---|---|---|---|
| SCK | Serial Clock | I/O | — |
| TXD | Transmit Serial Data or Master Out Slave In (MOSI) in SPI Master mode or Master In Slave Out (MISO) in SPI Slave mode |
I/O | — |
| RXD | Receive Serial Data or Master In Slave Out (MISO) in SPI Master mode or Master Out Slave In (MOSI) in SPI Slave mode |
Input | — |
| RI | Ring Indicator | Input | Low |
| DSR | Data Set Ready | Input | Low |
| DCD | Data Carrier Detect | Input | Low |
| DTR | Data Terminal Ready | Output | Low |
| LCOL | LON Collision Detection | Input | Low |
| CTS | Clear to Send or Slave Select (NSS) in SPI Slave mode |
Input | Low |
| RTS | Request to Send or Slave Select (NSS) in SPI Master mode |
Output | Low |