After several months, and fully dedicating a weekend to this project, I have pieced together from various sources (especially this forum), enough information to make an Accessory Port programming cable for the Motorola GM/CDM radios that will work with the generally available FTDI based RIB-less programming cables with the 8p8c (aka RJ-45) plugs designed to be used in the front Mic port.
Most materials I had found were for the older MaxTrac, and were designs for interfacing with a RIB Box, so I decided to write this guide for anyone else who needs to adapt a modern modular programming cable, to program a GM/CDM radio via the Accessory Port.
I have a couple of CDM1550-LS+ radios with remote heads installed in my vehicles. So taking them out and attaching a head to them on the bench when I needed to make programming adjustments became quite a pain.
The CDM1250, and 1550 at least, do not have a “Mic OFF Hook” pin built in to the Accessory port like the older radios. I had to program Pin 14 (DIG_IN_OUT_8) as “Mic OFF Hook” to use as a replacement for the front Mic ports “HOOK” function on pin 6. I chose Acc. pin 14 because, though it is not assigned a function in the Default profile, the Repeater profile assigns this function to pin 14, and it made sense rather than choosing a random pin for this function.
Map of front Mic port to Accessory port connections
All Mic pinouts reference the standard USOC and TIA T-568 8p8c pin numbering. I have included 10p10c numbers as a reference as the Motorola Mic port is actually a 10p10c connection.
10p10c - 8p8c - Acc. - Acc. Port
Pin - Pin - Pin - Function
======================================
1 - NC - NC - (Not used)
2 - 1 - NC - (Not used)
3 - 2 - 17 - BUS+
4 - 3 - NC - (Not used)
5 - 4 - 2 - EXT_MIC_AUDIO
6 - 5 - 7 - GROUND
7 - 6 - 14 - DIG_IN_OUT_8 (Programmed as “Mic OFF Hook”)
8 - 7 - NC - (Not used)
9 - 8 - NC - (Not used)
10 - NC - NC - (Not used)
Notes on Pins:
--------------------------------------------------------------------------------------------------------------------------
BUS+: For CPS Programming and Flashing
EXT_MIC_AUDIO: Front Mic port pin 4 “Mic Audio” is bridged to Acc. pin 2 EXT_MIC_AUDIO so they are electrically the same, though have different names.
DIG_IN_OUT_8: Programmed as “Mic OFF Hook” to use in place of Mic port pin 6 “HOOK”
I hope anyone else who needs to program their GM/CDM radios via the Accessory Port will find this useful.
Most materials I had found were for the older MaxTrac, and were designs for interfacing with a RIB Box, so I decided to write this guide for anyone else who needs to adapt a modern modular programming cable, to program a GM/CDM radio via the Accessory Port.
I have a couple of CDM1550-LS+ radios with remote heads installed in my vehicles. So taking them out and attaching a head to them on the bench when I needed to make programming adjustments became quite a pain.
The CDM1250, and 1550 at least, do not have a “Mic OFF Hook” pin built in to the Accessory port like the older radios. I had to program Pin 14 (DIG_IN_OUT_8) as “Mic OFF Hook” to use as a replacement for the front Mic ports “HOOK” function on pin 6. I chose Acc. pin 14 because, though it is not assigned a function in the Default profile, the Repeater profile assigns this function to pin 14, and it made sense rather than choosing a random pin for this function.
Map of front Mic port to Accessory port connections
All Mic pinouts reference the standard USOC and TIA T-568 8p8c pin numbering. I have included 10p10c numbers as a reference as the Motorola Mic port is actually a 10p10c connection.
10p10c - 8p8c - Acc. - Acc. Port
Pin - Pin - Pin - Function
======================================
1 - NC - NC - (Not used)
2 - 1 - NC - (Not used)
3 - 2 - 17 - BUS+
4 - 3 - NC - (Not used)
5 - 4 - 2 - EXT_MIC_AUDIO
6 - 5 - 7 - GROUND
7 - 6 - 14 - DIG_IN_OUT_8 (Programmed as “Mic OFF Hook”)
8 - 7 - NC - (Not used)
9 - 8 - NC - (Not used)
10 - NC - NC - (Not used)
Notes on Pins:
--------------------------------------------------------------------------------------------------------------------------
BUS+: For CPS Programming and Flashing
EXT_MIC_AUDIO: Front Mic port pin 4 “Mic Audio” is bridged to Acc. pin 2 EXT_MIC_AUDIO so they are electrically the same, though have different names.
DIG_IN_OUT_8: Programmed as “Mic OFF Hook” to use in place of Mic port pin 6 “HOOK”
I hope anyone else who needs to program their GM/CDM radios via the Accessory Port will find this useful.
