| Pin | Signal | Description |
| 1,2,3 | CTS,RTS,DSR | shorted together |
| 5 | RxD | in |
| 6 | TxD | |
| 7 | BOOT# | flash enable - short to ground |
| 8 | data enable | 120 KOm short to ground |
| 11 | mic in | |
| 12,13,14,15 | Gnd | |
| 16,17 | +5v | |
| 18 | charge |
M330 and M341i are using little different connectors, but they may be fitted with a knife

