The rear accessory connector on Motorola SM50 and GM300 mobile two-way radios provides access to audio, PTT, signalling, and programmable I/O functions. This 16-pin connector is specific to the SM50/GM300 family and allows external speakers, microphones, and alarm devices to be wired to the radio. Only the pins listed below are covered here.
| Pin | Signal | Description |
|---|---|---|
| 1 | EXT SPK- | Speaker connection OUT - |
| 2 | EXT MIC | Audio input for MIC |
| 3 | EXT PTT | PTT push to talk (MIC PTT) |
| 4 | EXT ALARM | External alarm HORN |
| 5 | INPUT | FLAT Audio Input |
| 6 | SPARE | SPARE Connection |
| 7 | GND | GROUND |
| 8 | COR | (COR) Programmable O/P |
| 9 | EMERG SW | EMERGENCY Switch(Foot sw) |
| 10 | IGN Sense | IGNITION SENSOR |
| 11 | RX AF OUT | AUDIO OUTPUT FROM RECEIVER |
| 12 | I/O | INPUT/OUTPUT PROGRAMMABLE |
| 13 | SW A+ SENSE | SW SENSOR A+ |
| 14 | I/O | INPUT/OUTPUT PROGRAMMABLE |
| 15 | INT SPK + | INTERNAL Speaker connection OUT + |
| 16 | EXT SPK + | EXTERNAL Speaker connection OUT + |
Notes
Pin numbers refer to the connector on the rear of the radio; pins not listed are unused or reserved.