Com-Spec Radio Firmware Hacking. (Convert your PR-100A into a R-300A)

[TT3D]

Hello! I was playing around with my PR-100A when I had an idea. The 100 and 300 series receivers are very similar, maybe they share hardware? After taking apart my PR-100A, I saw there were two more five pin ports for additional number wheels. The 100 uses two wheels, the300 uses three, and the 600 (and 400) uses four. After a bit of looking around, I saw it uses a PIC16F1938 micro controller which can be dumped with a PIC Kit programmer. After ordering, a bit of waiting, and a bit of soldering I got this.



I fired up MPLAB IPE and prayed that copy protection was not enabled as that would turn this from a $25 project to a $250-2500 project. Luckily it wasn't and I had a fresh HEX file.



The resulting file from my August 2017 manufactured radio is attached below (Changed from .hex to .txt so it would upload). As for the additional wheels, they are Hampolt model PF52 BCD switches soldered to five pin JST-ZH connectors. I will post more on these once they arrive to me so stay tuned!

Now here for the part I need help with. I do not own a R-300A and Com-Spec is no longer in business. To finish this project, I would need access to someone's R-300A to solder a few communication wires to so I can pull the firmware. If you will be at LDRS hosted by URRG this summer, I could bring the equipment to pull it there. Otherwise I would pay shipping for someone to send me a radio and back to pull the firmware. The soldering is all done to dedicated pads so there is little to no risk of damage to the radio.

 

[ksaves2]

Com-Spec stuff was so overpriced at the time. But was figuratively bulletproof. Was the only game in town for tracking years ago. I thought it cost too much so got a Ham radio General license so I could do APRS tracking. Com-Spec was in the 200Mhz range and their receivers with handheld Yagi antennas
and attenuators were excellent when I saw them being used by others.
I built trackers on the cheap along with an attenuator and used a ham H/T to track along with my homemade Yagi antennas. I see the Com-Spec site is still up but they mentioned they ceased operations last year.
GPS tracking made inroads and become more economical that largely put Rf tracking by the wayside or for backup ground tracking.
If I was the user above, I wouldn't dink with a Com-Spec receiver unless they can get the R-300A to peruse and if it looks like too much
of a modification. Leave it alone or one may dork their receiver and render their tracker(s) useless. That is a consideration if they own Com-Spec trackers.
Mess up the receiver and will be in dire straights. Be very certain a conversion will work or their entire system will be useless.
I tried to receive Com-Spec stuff on an all band receive H/T, Kenwood TH-F6 and it didn't work well. I just worked with it for a short time and if
anyone has a fix for that post it. Then again, I gave my Com-Spec tracking transmitter away to a fellow flier. Club I was in at the time had a receiver
members could use. Just had to buy the tracker from Com-Spec. Rf and GPS tracking advanced so fast I gave up on Com-Spec.
Put a small GPS tracker in a rocket and call it good. Shoot, I had a lawn dart one time and went to the spot where the rocket got a position out
50 feet in the air on the way down. Sure enough I saw the very end of the fincan and was able to dig out the rocket to get the chutes back along with my engine casing and retainers.
Of course the electronics were trashed but I was able to salvage some useful parts. I had cataracts at the time and missed one leg of the ematch. The homemade MAD unit didn't have continuity testing.
Kurt KC9LDH

 

[TT3D]

I would agree that there is no real reason to bother hacking the reciever. There are others making compatible transmitters which can be programmed to the 100A frequencies. Having additional channels offers near zero benefits. I also agree that GPS has gotten so cheap and is generally better and easier for most users. Although they were overpriced compared to alternate systems which have come out in the past decade, the hardware is still impressively well made and I would like to see what I can do with it.

The reasons I am doing this and publishing it are:

1: It is a fun and reverse engineering project. The ultimate goal would be to RE the code and write custom firmware.
2: The company is no longer so I would like to put as much information out on these for anyone to keep their equipment running as long as possible including various firmwares for them. I have already helped one user who had a few wires come dislodged, having mine apart already made it easy to give the information needed to resolder correctly.

 

[ksaves2]

I would agree that there is no real reason to bother hacking the reciever. There are others making compatible transmitters which can be programmed to the 100A frequencies. Having additional channels offers near zero benefits. I also agree that GPS has gotten so cheap and is generally better and easier for most users. Although they were overpriced compared to alternate systems which have come out in the past decade, the hardware is still impressively well made and I would like to see what I can do with it.

The reasons I am doing this and publishing it are:

1: It is a fun and reverse engineering project. The ultimate goal would be to RE the code and write custom firmware.
2: The company is no longer so I would like to put as much information out on these for anyone to keep their equipment running as long as possible including various firmwares for them. I have already helped one user who had a few wires come dislodged, having mine apart already made it easy to give the information needed to resolder correctly.

Best of luck to you! I don't have the skills to do that. As I recall 15 years ago Com-Spec was the only game in town for Rf/Df rocket tracking and APRS/GPS was in its' early days. Got the Ham General license so I could do APRS tracking with the then "new" Beeline" stuff. Expensive but I could get the incoming positions ported to be plotted on a map in a laptop in real time. I thought that was so cool and no one else was doing it at the time at the launches I attended.

What I saw one time in the early days was a flier with a Ham license would be inputting the last known position from a Beeline GPS tracker into a handheld Garmin mapping GPS and was totally unaware that the GPS units one inputs to the handheld mapping GPS was important. What came out of the Beeline tracker might be different than what the handheld Garmin was setup to process.

The fellow I saw was fretting right and left as he couldn't find his rocket. I was aware of the units issue and volunteered to look at his handheld GPS unit. Saw the screen on his D7A and the units were mismatched for manual input to his handheld Garmin GPS. I showed him the adjustment that needed to be done to his handheld Garmin GPS and he found his rocket.

His verbal gratitude made my day. I was so happy I was able to help a fellow flier find their rocket when they were still new at the technology. I had studied
and was acclimated to the technology but I was glad I was able to help another find their rocket which from the size of it was a pricey investment. It was a nominal flight so it's loss would have been a sizable loss in dollars. Got it back for him though!

Of course, I still think a Kenwood D72A interfaced with a serial cable to either a handheld Garmin 60Cs or 60CsX is the absolute best for portable APRS/Beeline GPS tracking. Have a "map in hand" with the last known position and the Garmin units can plot a course and take one to the last known position.
Very easy to carry around.

That was some time ago though. The Featherweight stuff can use software on a phone to do the same thing now. The Garmin 60 units are out of production too. Shoot just use a phone GPS now but that interface between a D7A and later the D72A was absolutely fantastic back then. I invite folks to post the "newer" GPS tracking remedies as I haven't been able to fly for awhile. (Wife died, I retired and have guardianship to take care of a mentally handicapped adult son.) The build pile is still there though.

When Eggtimer came out with the simple NMEA live download I asked a Ham operator who wrote an APRS program for tracking if it was possible to track the simple NMEA positions instead of APRS packets. He came right back and told me how to run two instances of his program to do NMEA tracking and get my local position and rocket NMEA (Eggtimer stuff) plots on the same map! Was simple to do too!

I was probably the only one doing that at the time. It was a photomap that I was able to download and store on the laptop. Again nice to see the rocket likely landed next to a barn, not on the road or not in the tree in the photomap. I could download the maps from the then high speed internet at work and didn't need an internet link at the launch site!

Oh one point here is yes, on the up side one won't see any positions due to the so-call CoComm or whatever high speed restrictions on GPS. I found that even after apogee under drogue chute it took some time to get positions coming in to the receiver. Cripes I had one rocket for whatever reason didn't give out a good GPS position until it was under the main parachute! I know as it was within sight when it deployed! GPS tracking weirdness.

Found out if one spends a pile of money on tracking technology many times their rockets will recover within SIGHT! That's pretty crazy but happily happened to me more often than not.

There is that time though when a rocket goes out of sight and drifts far on the range where that last known GPS packet is a lifesaver to get a nominal recovery done.
Kurt