Motorola GM950E, Service Manual

Page: 223 / 228

Microphone Connector
External Device Connectors B-3
2.0 Microphone Connector
The radio is Þtted with an 8-pin ÔTelcoÕ connector which is connected as follows:
Pin 1.
- No connection.
Pin 2.
- No connection.
Pin 3.
- Microphone (or internal) Hook
This port reads Ô0Õ when the microphone is on-hook and Ô1Õ when the microphone is off-hook. It is
assumed that the hook is a mechanical switch, so the software will always debounce this input.
Pin 4.
- Ground
Pin 5.
- Microphone audio
This microphone signal input is common with the microphone signal input on the accessory connec-
tor and is connected to the microphone path input of the AFIC.
Note: Only one microphone should be connected at any one time.
Pin 6.
- Microphone (or Internal) PTT
The microphone PTT is active low and so this port reads Ô0Õ when the PTT is pressed and Ô1Õ when
the PTT is released. It is assumed that this PTT is a mechanical switch, so the software will always
debounce this input.
The microphone PTT line is also available at the internal connector (J0102:1) as a bi-directional line,
i.e. an internal option can use the line, both to key-up the radio, and to know when the radio is
already keyed-up. For this to work, microprocessor port C4 has to be reconÞgured as an output and
driven low whenever any other signal, other than the microphone PTT, e.g. external PTT, causes the
radio to key-up.
Pin 7.
- BUS+
This line carries the data for the single line serial comms system used in the radio. The RSS will pro-
gram the radio through this socket. The line is also available at the accessory connector Pin 6.
Pin 8.
- Handset Audio
This line provides buffered audio for a handset.
Pin Name Type Connected To
1 - - -
2 - - -
3 Mic. Hook Digital input Port A7
4 GND Ground -
5 Mic. Audio Analogue input AFIC TX IN
6 Mic. PTT Digital i/o Port C4
7 BUS+ Digital i/o Port D0 and Port D1
8 HANDSET Analogue output Buffered RX audio
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