| SCK | Serial Clock | I/O | — |
| TXD | Transmit Serial Data or Host Out Client
In (MOSI) in SPI Host mode or Host In Client Out (MISO) in SPI Client
mode | I/O | — |
| RXD | Receive Serial Data or Host In Client
Out (MISO) in SPI Host mode or Host Out Client In (MOSI) in SPI Client
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 |
| LONCOL | LON Collision Detection | Input | Low |
| CTS | Clear to Send or Client Select (NSS) in
SPI Client mode | Input | Low |
| RTS | Request to Send or Client Select (NSS)
in SPI Host mode | Output | Low |
