| No. | Pin | Pin Direction | Remarks |
| 1 | GND | enter | Module ground |
| 2 | GND | enter | Module ground |
| 3 | VCC | enter | Module power positive reference, voltage range: 4.5~15V DC |
| 4 | VCC | enter | Module power positive reference, voltage range: 4.5~15V DC |
| 5 | RESET | enter | Module reset pin |
| 6 | AUX | output | Used to indicate the working status of the module; the user wakes up the external MCU, and outputs a low level during the initialization of the power-on self-test; (can be suspended) |
| 7 | TXD | output | TTL serial port output, connect to external RXD input pin; |
| 8 | RXD | enter | TTL serial port input, connect to external TXD output pin; |
| 9 | M1 | Input (very weak pull-up) | Cooperate with M0 to determine the 4 working modes of the module (not floating, if not used, it can be grounded) |
| 10 | M0 | Input (very weak pull-up) | Cooperate with M1 to determine the 4 working modes of the module (not floating, if not used, it can be grounded) |
| 11 | GND | enter | Module ground |
| 12 | GND | enter | Module ground |
| 13 | ANT | output | Antenna interface (high frequency signal output, 50B ohm characteristic impedance) |
| 14 | GND | enter | Module ground |
| 15 | GND | enter | Module ground |
| 16 | GND | enter | Module ground |
| 17 | GND | enter | Module ground |
| 18 | GND | enter | Module ground |
| 19 | GND | enter | Module ground |
| 20 | STATE | output | Module status indication output, if not using floating processing |
| 21 | 485-EN | input Output | The enable control pin of the external 485 chip can be suspended if it is not used |
| 22 | NC |
| Don't care, hang in the air |
| 23 | NC |
| Don't care, hang in the air |
| 24 | NC |
| Don't care, hang in the air |
| 25 | SWDlO |
| Don't care, hang in the air |
| 26 | SWCLK |
| Don't care, hang in the air |
| 27 | GND | enter | Module ground |
| 28 | 3.3V |
| Don't care, hang in the air
|
