• I don't know about Arducopter 2.8.1, I'm using 2.9.1b and this is how I connected the RSSI of my FrSky D8R-XP receiver to my APM 2.5 for display in MinimOSD today and it works:

    Made an RC filter cable using a 4.7K resistor and a 10uF capacitor. This converts PWM RSSI into a smooth analog RSSI.

    RSSI is on the channel 2 signal pin of my D8R-XP receiver, so I plugged the input side of the cable into that channel and the I plugged the output side into port A0 on the APM 2.5. Use signal and ground wires only.

    Then in Mission Planner, I went to the advanced parameters list and searched for RSSI PIN and set it to A0 and saved it.

    I didn't disable COPTER_LEDS as is sometimes advised in old posts. Perhaps that only was an issue in older firmware.

    Then in the config tool of MinimOSD-extra, I added the RSSI indicator to my panel, and then calibrated it following their wiki.

    So no hardware hacking or custom firmware compilations are necessary.

    You can use other values for the RC filter, as long as the time constant at least 27ms. I used:

    • I am having some issues with my RSSI readouts. I am using a Frsky Delta 8 rx (Aurora 9 tx) and im not sure if my RSSI reading are not displaying correctly via the APM 2.5 / minimOSD or if the issue lies elsewhere.

      I have added the filter with your specs (4.7k resistor and 10uF cap) to the RSSI channel.

      Firstly I have a weird issue where the voltage displayed drops 30% when I turn the tx off and then back on again. I measured the voltage directly from the rx and it's 3.1v initially and then when I turn off the tx it drops to 0.12v. When I turn the tx back on it only goes to 2.1v. If I power cycle the rx though it goes back to 3.1v.

      Secondly and more concerning is the lack of range. I took my quad for a test fly/tune today and the RSSI value in the OSD dropped to zero after walking no more than 20 meters from the quad and I got an "low rssi" warning in the OSD- this was in full power mode not using any reduced power setting on the tx. Incidentally before I put the goggles on to fly via FPV, I did an LOS autotune and the quad got a good 40 meters away a few times as part of the autotune process and I brought it back each time with no range issues. It was just when I looked later via the goggles that I noticed the RSSI readings and warning.

      I have tried two brand new rx's with same results. I'm not sure if I can trust the RSSI readings. Any thoughts on where to start with this problem?

    • 3702662008?profile=original
      Further to this it seems that there actually no RSSI readings been seen by the APM 2.5 board itself ?? I have set the A0 pin for RSSI in the Full Parameter List and added an RC Filter.  Any idea why the RSSI readings aren't been seen by the board? Could my RC Filter be wrong?

    • Sorry - I had the wrong field selected in the HUD.  Looks like the rxrssi field is getting the correct rssi readings but its not being passed onto the minimOSD properly.  Any suggestions on how to fix this?


    • Following your schematic using 4.7k resistor and 10 uF capacitor worked like a charm for me as well, using the following setup:

      APM 2.5 with Arduplane 2.78b

      FrSky D8R-II plus receiver running d8rxp_cppm27_build120926 firmware, configured for PPM, so only one cable between my APM and FrySky D8R-II plus (not counting the new RSSI cable).

      Nice to have this on my MinimOSD screen.  One caveat, so far, I've only tested on the ground but confidence is high that it will perform the same in flight.


      PS nice video on youtube TS!

  • Thanks for the info Jumpy.

    I have checked the Arducopter code for #define RECEIVER_RSSI_PIN and it does not exist. I am unsure what the current RSSI fields in MAVLINK are reporting but its not anything to do with a analog pin. Does someone know what goes on here?

    Also what programming environment do people use when editing this code other than Arduino IDE..


  • I don't think the APM can handle PWM RSSi, others have used a mod on MinimOSD to handle it direct for FPV work..  (MinimOSD Extra,


    Have a look at my quick guide for the APM 2.5 and it shows the details..,676.0.html

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