[Solved] MMDVM Repeater w/ HBlink

[VK3KYY]

Thats the same board which I have.

Its called the POG board.

I found at least one variant of the PCB

https://github.com/wojciechk8/MMDVM_pog

I found some other reference about how to reflash it

https://wiki.philpem.me.uk/hamradio/mmdvm/pog

Unfortunately, according to the article on reflashing using a USB to Serial, it looks like you have to solder to the chip. I'd recommend you just buy one of the cheap STLink dongles. They are only a few dollars and in the USA I think you can get them from Amazon.

(We have Amazon here in AU, but its completely useless. No local stock of anything. Most of the electronic items seem to be from Chinese vendors with 4 week shipping times. Its cheaper and quicker for me to get stuff direct from China on AliExpress)

[NA7Q]

Thanks for the extra info. I have ordered a dongle and it will arrive in just a couple days. We have local stock here from Amazon, but the shipping is slower due to the covid stuff going on. I'll try reflashing it this weekend. I did find newly compiled firmware for it. So that'll save me some time.

[VK3KYY]

Thanks for the extra info. I have ordered a dongle and it will arrive in just a couple days. We have local stock here from Amazon, but the shipping is slower due to the covid stuff going on. I'll try reflashing it this weekend. I did find newly compiled firmware for it. So that'll save me some time.

OK.

STLink work well. I'm not sure whether the updated firmware will help or not, but its worth a go.

From what I recall the board is seen as obsolete, because the STM32F105 processor is only powerful enough to decode some modes, e.g. DMR, and not handle all the modes that the Jumbospot will handle.

I think possibly the analog electronics got improved a lot in the later designs, e.g. like the one from Repeater Builder, but that board is substantially more expensive.

[EB3AM]

Hello everyone,
I have been making a repeater with mmdvm and initially used this same board.
I had a lot of problems with the sound quality (tremolo & pixelations) I was receiving from the network. Since I was working with a repeater that had no documentation on how to connect the mmdvm, I decided to change the board to one I already knew, to rule out issues, and to make sure what my problem was with the repeater.
The surprise was that once the levels of the new board were adjusted, the repeater worked perfectly.
In conclusion, the Chinese mmdvm board behaves strangely. Possibly the vco's are of poor quality and this results in DMR errors. In tests I did in c4FM mode I had no audio issues.
It may be the pre-installed firmware version (2018) but I am make & running dmo and repeaters using this firmware all over the country without problems. However, they are always boards placed on an Arduino due and connected to the raspberry via USB.

[VK3KYY]

My board seems to have a hardware fault on the Tx audio modulation

I could not adjust it even using MMDVMCal to produce a nice clean sine wave. So eventually I gave up with it.

I don't recommend that anyone buys one of these cheap MMDVM boards as they are very difficult to setup, even if they work at all.

[NA7Q]

This is one of my replacements. It's another POG variant. They come with newer firmware installed though. I've had no problems at all with this board, especially in tuning the audio. It's been a good board. These are more popular and easier to find online. They are cheap, but I really can't complain. It's hard to justify the expensive boards when you're on a low budget for building repeaters and nodes.
https://www.ebay.com/itm/US-MMDVM-Open- ... 2824445238

[NA7Q]

You guys might like this.


youtu.be/wdRQgCDUk_I

[M6SEU]

Hi. NA7Q
Excellent and i thought i was the only one that did that but i use a big rubber mallet.

[EB3AM]

This is one of my replacements. It's another POG variant. They come with newer firmware installed though. I've had no problems at all with this board, especially in tuning the audio. It's been a good board. These are more popular and easier to find online. They are cheap, but I really can't complain. It's hard to justify the expensive boards when you're on a low budget for building repeaters and nodes.
https://www.ebay.com/itm/US-MMDVM-Open- ... 2824445238

look X1 and X2 and compare with the other board... Maybe it make a difference!

[NA7Q]

I was able to successfully upgrade the firmware. However it did not resolve the issue. I surely won't be buying another one of those boards. The different style one I have is good all around. I have another on the way. We'll see if the quality is as good as the first one I purchased.