| 1 | 5V | Jumper short connected with VCC，for power input |
| 2 | VCC | Power input |
| 3 | 3.3V | Jumper short connected with VCC，for power input |
| 4 | GND | Ground |
| 5 | VCC | Power input |
| 6 | NC1 | / |
| 7 | NC2 | / |
| 8 | NC3 | / |
| 9 | RXD | RXD，to connect TXD of module for test |
| 10 | TXD | TXD，to connect RXD of module for test |
| 11 | AUX | Check more from manual of E22 module |
| 12 | M1 | Pin M1 for mode selection，suspending means“1”，when short connected with |
| GND, it is“0” 13 GND Ground，often work with M1 |
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| 14 | M0 | Pin M0 for mode selection，suspending means“1”，when short connected with |
| GND, it is“0” |
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| 15 | GND | Ground，often work with M0 |
