Build your own DTR CPS Programming Cable

Could someone who still has a programming cable (I sold mine off) figure out the pinout? You could take it apart or just meter the pins.
To be clear, the RS-232 CPS programming cable, not the flash cable.

I have a programming cable, but I don’t see any way of taking it apart without destroying it. The DB-9 is molded and there is another molded section that probably houses a RS-232 to USB signal converter. There is no continuity between the DB-9 and the DTR connector, except for DB-9 pin 5, which goes to DTR pins 1, 13, 14 and 16. It’s not a straight-through cable that is easily built, but requires some electronics.

Thank you for checking that.
I’m very surprised that the cable is not “straight through”, as it would make no sense to convert to a connector (RS232) that was long outdated even before the DTR came into being. Perhaps there’s some level-shifting circuitry, but again, I’m surprised. Typically cables are made using RS-232 because the native circuitry in the device is RS-232 and serial protocols are very simple.
I wish I’d hung onto my programming cable as I’d be happy to cut it open in the interest of science…

I agree with your reasoning, but this is Motorola we’re talking about here :slight_smile:

Remember that the flash cable USB D+ and D- leads go directly into the radio. That implies that the radio has the circuitry to handle USB signal levels, so RS232 to USB level shifting is needed on the RS232 cable. Who knows why they went with a RS232 programming cable when they could have gone with USB directly.

Here’s a link to a photo of the programming cable showing the extra molded section:

I doubt the radio has USB-host capabilities to manage a USB to RS232 converter.
Some old cell phones had RS232 and USB interfaces built-in.

I agree. I think some other pins must be used, but there is definitely “something” inside that lump. Hopefully one day someone will get curious enough to split it open and have a look.
Also, a complete pinout of the connector would be an amazing find!

Andy has a question earlier on programming cable wiring. It took me a while to use multimeter to check. it is complicated, not straight through. here is the result. DTR connector pin is numbered 1 to 17 with #1 is the outside one on the 3 - pin block. 232 cable has 9 pins, PIN number is marked. if you look at it with 5 pin on the top and 4 pin at the bottom, #1 is the top right one, and #6 is bottom right one.

  1. 232 #5 -> DTR shield, 1, 13, 14, 16. They are all connected straight as ground
  2. 232 #4, 3, 7, 9 (any of these) -> DTR #1, 13, 14, 16 at 5k ohm, #3 at 20k ohm.
  3. 232 $4, 3, 7, 9 are not internally connected straight, they have 10k -20k ohm in between
  4. 232 #4, 3, 7, 9 are not 100% isolated from the rest of DTR pins. They have about 30 M ohm to DTR #4, 8, 9,20, 12, and 7M ohm to #5, 6, 11

By checking, now these findings make sense. There is no straight no resistance wiring in program cable. Based on the wiring on flashing cable, it seems hard to make a dual use cable since these two wiring is quite different.

My hope is that someday someone will be willing to open up the CPS “lump” and figure out what’s going on inside. Like the flash cables, these programming cables could one day disappear too!

If you have a schematic for the cable I can possibly convert the USB connections back to either a DB9,15 or 25 if that is the only issue.

OK I read the whole thread. if you want to convert your USB to a db9 these sre the connections
USB - txd goes to pin 2 of the db9
USB - rxd goes to pin 3 of the db9
USB - gnd goes to pin 5 of the db9
USB -+5v will have to be supplied outside of the db9

for a db25 connector
USB - txd goes to pin 2 of the db25
USB - rxd goes to pin 3 of the db25
USB - gnd goes to pin 7 of the db25
USB -+5v will have to be supplied outside of the db25

All the USB to serial adapters I have looked at use the USB port as the connection to the computer. So if for whatever reason you need to use a db9 or db25 you will need to have a power supply that feeds the 5v to the DTR

Hey Iceberg;

The concept would be to build a single cable that does both the firmware flash (which we’ve successfully created) as well as CPS programming.
The cable would have just a single USB connection and a switch to go between Flashing and Programming.

Converting USB to RS-232 is not the issue, it’s figuring out how the connections are wired in the Moto CPS programming cable.

Ok so what is different in the CPS cable.?

from your comments I take it that the flash cable diagram here
post 30.
only flashes a radio. The CPS cable only programs the radio. Obviously a CPS cable will need to be pin out checked. Reading through the forums and based on my Moto experiance I would say that the DTR is of the same timeline as the IDEN hardware. Knowing Moto the IDEN cable should almost be identical to the DTR with the possibility of the DTR end being to different pinouts.

It would not surprise me to find that the TXD and RXD lines are the same and there is just a diode added across 2 pins or an additional pin grounded for the DTR programming mode.

Ill do some R&D on IDEN cables and see if a diagram cannot be found.

Its a start delving deeper.

Sounds like you’re picking up what we’re putting down…

The key will be someone opening up the “Lump” in the CPS cable to see what magic it contains. (Only to find an unidentifiable IC or something…)

If there is a lump expect a 1 wire chip. The good news is they can usually be read and cloned. Not that we would do that.

I did find some manuals but they are all BSM. If I can get a DSM on a iden that uses the ‘same’ connector we will have a starting point.

Thanks - perfect info for what I need.