Rx RSSI parameters request


I have FRSky which seems to output 0-3v for their RSSI, whereas APM 2.5 code seems to use 0-5v

I'm not a programmer, but I can see it would need a small code tweak to rescale the 0-5v range to 0-3 by multiplying it by 0.6. Correct?

Optionally, it would be nice to have a parameter in APM/Mission Planner to set that scale.

How do I do this so I can get FrSky RSSI working?



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  • I made contact directly with FRSky and they had the following information.

    So all that would be required to support the FrSky receivers would be an option in Mission Planner config to accept 0-3.3v or 0-5v (or some Zero to other-voltage-value) 


    The RSSI on TFR8SB is PWM as default, which you can convert to analog voltage RSSI 0~3.3V

    You can convert the analogue rssi out put as below drawing.



  • Developer
    FrSky uses PWM for RSSI, not a voltage. The Pulse is 3.3v but its the length of the pulse that is the indicator. You need a circuit to convert pulse width to a scaled 5V signal for the APM.
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