Hi all, might be a shot in the dark but here goes... I bought a knockoff mmdvm pi hat to use with my Retevis RT3S for use on 444.90. I am familiar with imaging SD cards for other operating systems. I'm using pi-star on a RPi3b, the May 2020 version.

The pi and hat boot fine, I've got the set up configured for my WiFi. The logs show its connected to Brandmeister. When I set up a static TG on Brandmeister, like 91, I can see other hams DMR IDs, calls, names, etc on the hat's LCD screen. Further, the RT3S can hear the TG conversation, when tuned to 444.90, digital, promiscuous mode on.

The problem is that the hat doesn't hear the RT3S. When I transmit on 444.90 digital, TG91 or TG9990, the hat's screen stays blank. Parrot does not respond. I'm using CC1, TG2, the default on the pi-star image. I have also tried from -1000 to 1000 in the Rx and TX offset, expert settings. The pi-star wiki gave a few leads, but none have turned out well.

I used another 440 ht to validate the RT3S is transmitting something on digital by setting up a simplex QSO with a friend on the same frequency. The short QSO went fine and audio was heard both ways.

So reddit, please help a newbie that just wanted to get his new DMR toy on the air. Any and all leads will be considered, likely tried and I will update this thread on results.

Good day!

I'm in a bit of a quandary. I recently purchased a "full-duplex" Pi-Star. When I do "sudo pistar-findmodem", I get " Detected MMDVM_HS (GPIO): /dev/ttyAMA0 (MMDVM_HS_Dual_Hat-v1.4.17 20190529 14.7456MHz dual ADF7021 FW by CA6JAU GitID #cc451c4) ".

But...

The hotspot came configured with a "MMDVM_HS_Hat (DB9MAT & DF2ET) for Pi (GPIO)" as the configured radio/modem type.

I *do* have my Rx and Tx freqs set differently, and the modem does work that way, except it doesn't appear to be duplex, and I only have TS2 enabled. I did go into "Configuration|Expert}MMDVMHost"DMR Network" and set Slot1 and Slot2 to both read "1". The dashboard now shows Slot1 as enabled.

I have my handheld programmed to use slot 1 for a couple of things (like TG4000 for unlink), but regardless, the modem seems to see that as slot 2.

What I'm looking to do is have the ability to either change TGs or unlink/restart/whatever without necessarily needing to wait for an active conversation on Slot2 to be over.

Is this possible, or am I barking up the wrong tree? Does the radio/modem selection in the config page reflect reality, or do I need to select a different type of radio/modem? For what it's worth, if I select "MMDVM_HS_Dual_Hat (DB9MAT, DF2ET & DO7EN for Pi (GPIO)" the modem does NOT hear my handheld.

​

Any help would be greatly appreciated!

https://www.youtube.com/watch?v=10SZfMbeTl0#

​

I'd like to see this evolve into also supporting YSF and P25, perhaps using the mmdvm arduino radio type of interface. Something so folks can talk on something into the various repeaters over RF.

Forgive me if this is a stupid question, but Im new to the whole DMR pi-star thing. Is it possible to use an HDMI monitor connected to the host ras-pi to view the pi-star dashboard?

I've just got my MMDVM_HS_HAT_DUPLEX working and I really like it. Wondering if there are any hacks to get it to do anything on analog instead of digital. Seems like this thing could easily be a small homebrew repeater.

Dear OM's,

I'm a proud owner of the ZUM radio MMDVM Pi module v0.9. This modem; https://www.pikkaart.net/f/MMDVM-Pi.jpg

How do I upgrade the firmware while the modem is attached to my Raspberry Pi? I found this page a description of a French OM. Is this the right way? (STM32F446).

https://www.rs-online.com/designspark/building-a-digital-mobile-radio-repeater-part-1-mmdvm

I want to be sure, don't want to screw up my modem ;-)

Vy 73 Michel pe1pts

PS for any interest, this is my MMDVM repeater; https://www.pikkaart.net/dv/images/Tait_II_UHF_repeater.jpg

There are lots of illegal standalone MMDVM_HS clone boards that are being sold from China, they've been branded "chinspots" or "chinaspots" and are marked up as "jumbospots".

As radio amateurs we should be supporting the efforts of the developers and designers, the open-source community that supports us and we should be respecting the license that this hardware was released under.

If you are not familiar with this license, it means that boards from this design can be produced at home (or at a radioclub for example) and they can be sold to recover the costs without profit, but they must not be sold commercially.

The license also forbids the removal of the original licensing agreement, which is what the Chinese clone manufacturers have done.

Do the right thing and don't support the fake Chinese clone boards.

I've set up this subreddit for those who would like to discuss the excellent MMDVM project that was originally created by Jonathan Naylor (G4KLX).

The project supports D-Star, DMR, System Fusion, and P25 and is especially interesting because of the fairly recent developments with the MMDVM powered hotspots based on the ADF7021 transceiver IC (such as the Zumspot and MMDVM_HS).