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CM300d accessory connector pins

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CM300d accessory connector pins

Postby arlojanis » Wed Jul 08, 2015 10:17 am

Are the CM300d accessory connector pin functions the same as the CM300? If not, what are they?
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Re: CM300d accessory connector pins

Postby Wiregeek » Fri Feb 05, 2016 11:22 am


The CM300D is almost a completely different radio from the CM300. The 300D is a "Trbo Light" radio, and supports a subset of the MotoTRBO features and options from the XPR series. The 300 does not. Additionally, the 300D programs using TRBO CPS, while the 300 uses the Commercial Series CPS.

Below is the pinout chart for the CM300d, pulled from CPS help file.

Pin No. Pin Name Pin Function

1 Speaker- Speaker - (3.2 ohm minimum impedance)
2 Ext Mic Audio Rear External Microphone Input4
3 GPI_1 (PTT) 5V Level GPIO, PTT Input 1
4 VIP_1 (Ext Alarm) 12V Supply, External Alarm
5 Flat TX Audio Data Input3
6 UART CTS Motorola Internal Use Only7
7 Ground Ground
8 GPIO_4 5V Level GPIO
9 Emergency SW Emergency Switch Input
10 Ignition Sense Ignition Sense Input6
11 RX Audio Receive Live Audio2
12 GPIO_7 5V Level GPIO
13 SWB+ Switched Battery Voltage
14 GPIO_8 5V Level GPIO
15 RSSI Receive Signal Strength Indicator5
16 Speaker+ Speaker + (3.2 ohm minimum impedance)
17 UART TX Motorola Internal Use Only7
18 UART RX Motorola Internal Use Only7
19 UART RTS Motorola Internal Use Only7
20 Ground Ground

1 Pulling this line to ground activates the Ext Mic Audio input.

2 This input has a fixed level (independent of volume level) for received audio signal, including alert tones. Flat or de-emphasis are programmed by CPS. Output voltage is approximately 330 mVrms per 1kHz of deviation.

3 This input is for injecting signals into the transmit path that should not be filtered; for example, the analog output of a modem. The nominal input level is 150 mVrms for 60% deviation and the input impedance is greater than 25k.

4 This microphone signal is independent of the microphone signal on the front microphone connector. The nominal input level is 80 mVrms for 60% deviation. The DC impedance is 660 ohms and the AC impedance is 560 ohms.

5 A receive signal strength of -120 dBm gives about 1.12 Vdc at pin 15. A receive signal strength of -60 dBm gives about 2.44 Vdc at pin 15. The receive signal strength for levels in between can be linearly calculated. For signals strengths greater than -60 dBm, the voltage stays relatively flat at ~ 2.44 Vdc.

6 Refer to the Radio Installation (Dash Mount) and Cabling Interconnect Diagram for Dash Mount diagrams in the MOTOTRBO Mobile Installation Guide for wiring information.

7 Caution: Applying greater than 5V to the pin can cause damage to the circuit.

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Re: CM300d accessory connector pins

Postby RFguy » Fri Feb 05, 2016 11:32 am

FYI: The CM300d uses the same physical pins as the CM300

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