| serial number | Pins | Pin orientation | remark |
| 1 | GND | input | Module ground |
| 2 | GND | input | Module ground |
| 3 | VCC | input | The module power supply is positively referenced, and the voltage range is 4 5~15V DC |
| 4 | VCC | input | The module power supply is positively referenced, and the voltage range is 4 5~15V DC |
| 5 | RESET | input | Module reset pin |
| 6 | AUX | outpu | Used to indicate the working status of the module; The user wakes up the external MCU and the output is low during POST initialization Level; (Can be suspended)
|
| 7 | TXD | output | TTL serial output, connected to external RXD input pin |
| 8 | RXD | input | TTL serial output, connected to external RXD input pin |
| 9 | M1 | Input (very weak pull-up) | In conjunction with M0, determine the 4 working modes of the module (non-suspended, groundable if not used). |
| 10 | M0 | Input (very weak pull-up) | In conjunction with M1, determine the 4 operating modes of the module (non-suspended,groundable if not used). |
| 11 | GND | input | Module ground |
| 12 | GND | input | Module ground |
| 13 | ANT | output | Antenna interface (high frequency signal output, 50 ohm characteristic impedance). |
| 14 | GND | input | Module ground |
| 15 | GND | input | Module ground |
| 16 | GND | input | Module ground |
| 17 | GND | input | Module ground |
| 18 | GND | input | Module ground |
| 19 | GND | input | Module ground |
| 20 | STATE | output | Module status indication output, if no dangling processing is used |
| 21 | 485-EN | Input/output | The enable control pin of the external 485 chip can be used if floating processing is not used |
| 22 | NC |
| No need to care, dangling handling |
| 23 | NC |
| No need to care, dangling handling |
| 24 | NC |
| No need to care, dangling handling |
| 25 | NC |
| No need to care, dangling handling |
| 26 | SWDlO |
| No need to care, dangling handling |
| 27 | GND | input | Module ground |
| 28 | SWCLK |
| No need to care, dangling handling |