Marico

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Mavlink compatible OSD
« on: August 26, 2021, 09:36:30 pm »
Hi,
I connected Holybro OSD (Mavlink based OSD) and don't know why it won't output RSSI value (RSSI Icon/value is missing but is configured in OSD Config to show). On GCS RSSI is configured on channel 8  (my receiver sends rssi value over chan 8) and it is properly displayed on Input tab. Does Librepilot Mavlink implementation lacks of RSSI value?


EDIT: Never mind, I flashed it with Revo MinOPOSD (LP_All_From_Revo170818.hex) and it works now!
« Last Edit: August 26, 2021, 10:46:44 pm by Marico »

Re: Mavlink compatible OSD
« Reply #1 on: August 26, 2021, 11:05:02 pm »
I am not the most knowledgeable on OSD, but here are some thoughts.

Are you using the configurator that HolyBro recommends?  Not some other configurator that you downloaded.

Quote
Does Librepilot Mavlink implementation lacks of RSSI value?
If configured to display RSSI, I expect that the OSD should display the RSSI icon/text whether or not there is RSSI info coming in.  Further, if you power on the OSD but not the FC, the OSD will have no idea what FC or protocol is being sent and can't "hide the RSSI because of protocol" if that is even a possible thing.  To be clear, it is still possible for it to "hide RSSI until it gets valid RSSI data" if it is coded that way.  I have no idea how it is coded.

Thus is seems more likely that it is not capable of RSSI or that RSSI has not been turned on correctly with the correct configurator?

There is a special compile option for Mavlink OSD (Scarab version) to have LibrePilot compatibility.  I believe that without that, it will mostly work, but there may be some small things that don't.  I don't know about the HolyBro version.
Code: [Select]
MW_OSD/Config.h://#define LIBREPILOT   // Uncomment this if you are using the latest LibrePilot MSP Module
   MW_OSD/Def.h:#ifdef LIBREPILOT

Also, you could look for updated HolyBro firmware/configurator for the OSD.

Finally, if HolyBro is compatible hardware, you could put other firmware on it or try to get the HolyBro source code.  These are advanced procedures.  Save/backup/download the current firmware before changing it in case you need to go back.
« Last Edit: August 26, 2021, 11:13:44 pm by TheOtherCliff »

Marico

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Re: Mavlink compatible OSD
« Reply #2 on: August 26, 2021, 11:45:39 pm »
I am not the most knowledgeable on OSD, but here are some thoughts.

Are you using the configurator that HolyBro recommends?  Not some other configurator that you downloaded.

My HolyBro contained ArduCam OSD firmware 2.1 and was configured with ArduCam OSD Config Tool. I found some info, that basically it use rssi connected to analog ADC input on the OSD board but can't find any info about rssi in mavlink. I found some posts from pixhawk users that they have the same problem with HolyBro (lack of rssi icon and flight mode). So I decided to reflash it with Revo MinOPOSD which use librepilot telemetry protocol instead of mavlink. After flashing rssi icons shows up and flight mode, too.


Quote
Does Librepilot Mavlink implementation lacks of RSSI value?
If configured to display RSSI, I expect that the OSD should display the RSSI icon/text whether or not there is RSSI info coming in. 

But when I configured to show "Distance to home" and "Height" icons  the first won't show when OSD & FC was powered on (only "Height" was displayed). "Distance to Home" (icon and numeric value) shows after a while (when GPS got fix?), so by analogy I thought there could be similar behavior with rssi (it won't show because  smth. is wrong configured in Revo).


Finally, if HolyBro is compatible hardware, you could put other firmware on it or try to get the HolyBro source code.  These are advanced procedures.  Save/backup/download the current firmware before changing it in case you need to go back.

As I said, I replaced orginal firmware with more compatible with librepilot telemetry.