Telemetry - OpenLRS and APM


I have been trying to get telemetry to work with my OpenLRS RX and TX. Been trying out different setups and baud rates but not got it to work.


The transparent serial bridge is working perfectly but when I try to connect the RX to the APM Telemetry port (port 3) I cannot connect via Mission Control. Running a serial monitor I can see traffic - ascii in the beginning saying something like "<startup_mode: ground>" and then binary. Seems to be ok... but not good enough to connect.


I think the problem might be related to bandwidth. OpenLRS supports 750 byte/seconds from the RX to TX. After looking at the documentation and source code I have not figured out how much data MAVLink protocol is configured to send per second.

Does anybody know?



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  • @Martin

    I see you merged 3.6.4 to your fork, but I'm having troubles compiling for DTFUHF DeluxeTx:

    In file included from openLRSng.ino:111:
    TX.h:5: error: 'UBRR0H' was not declared in this scope
    TX.h:5: error: 'UBRR0L' was not declared in this scope
    TX.h:5: error: 'UCSR0A' was not declared in this scope
    TX.h:5: error: 'UCSR0B' was not declared in this scope


    • Ah.I am badzz... Sh*t , I have seen the error but no time to check. I will try today.
      • I've set aside some time for actually trying to rewrite my stuff without libraries etc. so it should be closer related to kah's original branch... I hope this will also sort out the issues you guys are having. @badzz: once I get it working properly could you test the deluxe Tx for us? I got none lying around :).
        Current status: able to do basic connection in mission planner data rate 2. 35% link quality because of mavlink radio status packet injection not working properly yet...
        As a side note I believe if someone needs original openlrsng to work with APM you could go with one of the "hidden" data rates (settable from CLI). It should work ok with 4, although there's a bug in the serial uplink (will post a PR soon to kah) which causes uplink bytes to get lost in the outgoing serial buffer from tx.
        • sure .. I can test the deluxe tx. 

          If we can get kha to take a mavlink PR , you would be the hero for many people 8)

        • Thanks Martin for your work !

      • Ok I pb and thanks for your work to !

        here more info : Serial port successfully opened with ID: 15
        14:22:43 -- Module - OpenLRSng TX starting
        14:22:43 -- Requesting to enter bind mode
        14:22:43 -- PSP - Unknown command: 204
        14:22:45 -- Communication through Phoenix Serial Protocol was never established, connecting failed
        14:22:45 -- PSP - Unknown command: 204
        14:22:45 -- Serial port successfully closed

        To make it more easy to find, here the thread if necessary :

    • It was not compiling on deluxe tx but that's fixed on gitsly version.
      What means 'not working' ?
      • Compilation is ok with 3.6.4 from gitsly but impossible to setup with CLI.
        I need Ppm out on port 6/ Channel 5.
        (This is perfectly workling with 3.6.4 master from Kha)

        I can't enter on setup mode (it's ok with 3.5 gitsly). I've seen on rc group 2 people with same pb (geofrancis and another Guy)

        I have test the special chrome configurator (baddz) but I've same error Geofrancis : 'configurator never ...' (I don't remember the exact message and I'm with my phone).

        Thanks for help !
    • in tx.h you will need to change that first line but I am not sure what to put. 

      It works with FastSerialPort1(Serial1);

      then it does too big but if you do not need to change the packet size (new gitsly parameter , the rest can be modified through configurator chrome), you can disable the cli from the openlrsng.ino

      • H Matthias, 

        I'm trying to have functionnal Mavlink telemetry with 3.6.4 from Gitsly (big thanks to him !) but only 3.5 working.

        (I'm testing OpenLRS Orange HK 1W with OpenLRS Orange HK 100 mW)

        Do you say we must change something here ?


        #ifdef COMPILE_TX
        #ifdef __AVR_ATmega32U4__
        FastSerialPort1 (TelemetrySerial);
        FastSerialPort0 (TelemetrySerial); 


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