STM32-dvm / mmdvm_hs Rasp-Pi 3 Hat GPIO - No Receive

Help with other MMDVM Repeater Boards (with NO onboard RF)
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K5FER
Posts: 2
Joined: Mon May 13, 2019 10:32 am

STM32-dvm / mmdvm_hs Rasp-Pi 3 Hat GPIO - No Receive

Post by K5FER » Mon May 13, 2019 9:38 pm

I have a STM32-dvm / mmdvm_hs Rasp-Pi 3 Hat GPIO modem from Repeater Builder that I'm trying to figure out.
It's either the way MMDVMHost Modem TXInvert or RXInvert is set or it's the pin outs on the radio.
I have it connected to a Kenwood TM700 using the 6 pin DIN cable that came with the modem.

If I have TXInvert set to 0 and RXInvert set to 1 than I can hear traffic on the handheld and the OLED screen shows the stations talking. But when I key the handheld the Pi-Star App shows no receive on the screen and OLED screen on the modem shows nothing either. The D700 shows a receive signal and the Green led on the modem comes on.

Now if I reverse the settings TXInvert 1 and RXInvert 0 than I can't hear the traffic the D700 is transmitting and the handheld is receiving but there is no audio. If I transmit from the handheld the OLED screen shows my call and Pi-Star App shows my call and changes from listening to transmit.

It doesn't work if I set the settings to either 0 0 or 1 1.

This looks to be a polarity issue, I don't know is this can be fixed in the modem setting or do I need to modify the cable to the radio.

Are there more number choices with the Inverts or are these just a 1 / 0 or On / Off.

Thank you

K5FER
Posts: 2
Joined: Mon May 13, 2019 10:32 am

Re: STM32-dvm / mmdvm_hs Rasp-Pi 3 Hat GPIO - No Receive

Post by K5FER » Tue May 14, 2019 9:27 pm

So playing more with this modem connected to the D700 and the Anytone handheld, it's now working

TXInvert RXInvert Modem sends to Internet Audio Works on Handheld
0 0 Yes Yes
0 1 No Yes
1 0 Yes No
1 1 No No

Reseated the connectors and turned everything off and back on and now it works

Go figure

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