| MCU Pin | Si4438 Pin | Function |
|---|---|---|
| PB4 | GPIO0 | ???? |
| PC3 | GPIO1 | ???? |
| PC4 | nIRQ | Interrupt |
| PC5 | SCLK | SPI SCK |
| PC6 | SDI | SPI MOSI |
| PC7 | SDO | SPI MISO |
| PD2 | nSEL | SPI nCE |
| PD4 | SDN | Shutdown |
| PD5 | ---- | UART TX |
| PD6 | ---- | UART RX |
| ---- | GPIO2 | Antenna switch(TX) |
| ---- | GPIO3 | Antenna switch(RX) |