Whistler and GRE/RS USB Programming Cable DIY

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johnnylemo

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I thought I would start a new thread on this since it was hard to find current information in the old ones.

I had a Pro-97 and Pro-164 with the RadioShack 20-047 USB cable.
This worked fine for these radios.

I then bought a used Whistler 1065 to log P25 traffic.
The 20-047 worked fine for programming, but when I dumped trunking data from the scanner to the PC, it would lock up the cable and scanner after about 10 minutes of use.

I thought this might be because the cable was more than a decade old and was starting to fail.
Unfortunately, RS no longer sells the cable and Amazon's price seems rather high for what it is.

With the help of the forum I was able to find pinouts and details of the original cable. (Thanks!)

So here we are in 2017 and we all tinker with electronics (I assume).
This is a diagram I made to show how I built my own modern programming/data logging cable.

** Parts Required: **
  • x1 Arduino - any will do, but preferably use one with the 3.3v TTL and 8MHz crystal.
    If you have a 5v board then you can add some resistors to reduce the arduino voltage to 3.3v and it works just as well.
  • x1 3.5mm Stereo jack - Rip one out of something, or just hardwire a cut 3.5mm cable if you don't have a jack.
  • x4 jumper wires - You can also solder a stereo cable to the Arduino if not using a jack or breadboard.

** Text Instructions ***
  1. Short out the reset (RST) pin to the ground (GND) pin.
    This bypasses the arduino's processor and makes it act as a USB-Serial device.
  2. Connect the Sleeve of the 3.5mm cable to the Ground on the Arduino.
  3. Connect the Tip of the 3.5mm cable to the Rx on the Arduino, it may be labeled as TX with an arrow indicating that it's your serial devices Tx pin.
  4. Connect the Ring of the 3.5mm cable to the Tx on the Arduino, it may be labeled as RX with an arrow indicating that it's your serial devices Rx pin. If your Arduino board has 5v with 16MHz crystal, then you will need to wire in a resistor voltage divider. I didn't diagram it because I didn't need it, but you connect a 5k resistor to a 10k to ground. Double check your voltage before connecting it to your scanner. If you're only using the connection for data logging like I was, then you won't need to connect this pin at all.
  5. No code is necessary on the Arduino unless you won't to add in some automation or device actions.
  6. Plug your Arduino in via USB and then a stereo cable to the jack and scanner.
  7. The driver should already be installed and you're good to go!

** Diagram **

 
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fxdscon

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johnnylemo

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I needed a cable that day and already had spare Arduinos and jacks.

Plus, that cable is $30, this setup is reliable and only $6.
 

trp2525

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trp2525

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johnnylemo

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I went to the 4 shacks near me and they all stopped selling this cable a few years ago.
They said people are regularly coming in and asking for them.

But as I said earlier, this is $24 cheaper and has the ability to do a lot more than that cable.

For instance, I just set it up to turn on an LED across the network when a specific talkgroup gets logged.
 

kc2kth

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Great write up, thank you. It's always bothered me that my remaining RS scanners (106 and 197) required a proprietary cable that I didn't, until now, have any idea what it did. I like that we can whip one of these up with commodity hardware instead should mine fail (it hasn't yet).
 

AgVulpine

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Will this $1.43 USB adapter work? It uses TTL (0 to +3.3v) instead of RS-232 (-3.3v to +3.3v), I don't know which serial protocol the scanner cables used. (Hint: I know that RS-232 doesn't stand for Radio Shack, but Recommended Standard.)

If this will work, how does the wiring differ in 20-546's stereo vs mono adaptations?

IMHO, this would be the cheapest, sexiest and most straight-forward solution. If it works. I'll receive one to test in 3-5 weeks.

"New Ultra-stable USB to TTL CH340G UART Serial Adapter Module STC 5V/3.3V 6Pin"
https://www.ebay.com/itm/371691009393

Image attached.
 

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