Tuesday, 28 May 2019

RSSI for iNav - X8R L9R XM+

RSSI (Received Signal Strength Indication) is a measure of the RC signal strength between the RC transmitter and model.

Having RSSI as one of the OSD (On Screen Display) items in your FPV feed means you can see the signal strength as you are flying.





According to this excellent RSSI setup video by Droneracer101 there are 5 different ways to configure your receiver, transmitter and flight control board to enable RSSI for your OSD. He is demonstrating with Betaflight but the same setups work for iNav.

This post is just my interpretation of Droneracer101's instructions that relate to my three types of SBUS receivers.

1. X8R, X6R and X4RSB Telemetry receivers
The X series receivers transmit RSSI to your transmitter by default. You can use this value as an Input for a spare channel, which is transmitted back to the receiver / FCB.

On your Taranis

In the INPUTS page create a new input

I chose I-01 and renamed it I-RSI  but it can be any input.









Change Source to RSSI
Change Scale to 100dB












In the Mixer page create a new mix for a spare channel (eg. Ch 11 but can be any spare channel)











Change Source to I-RSI (I-01)
Change Weight to 200
Change Offset to -100

This adjusts the RSSI value to a meaningful number in the OSD








Using iNav configurator


Configuration page - Turn Analogue RSSI Off

Receiver page - change the RSSI channel to Ch11

OSD page - enable RSSI and position it where you want on the screen


2. XM+ SBUS receiver
Digital RSSI on SBUS Ch 8 or Ch 16 from receiver to flight control board.
Requires the specific firmware upgrade for the XM+ receiver.

XM+ RSSI firmware upgrade and OSD setup video

Once you have installed the RSSI firmware, follow the iNav Configurator instructions above but choose Ch 8 or Ch 16 depending on your firmware choice.

Ch 8 or Ch 16 must be spare in your Taranis.

3. L9R long range non-telemetry receiver. Analogue RSSI
Analogue RSSI via direct connection. This will only be possible if the FCB supports Analogue RSSI by providing a solder pad or pin, and the receiver provides an Analogue RSSI pin.

Matek F405 Wing and F722 Wing boards support Analogue RSSI. F411 Wing board requires MATEKF411_RSSI firmware to allow RSSI on the STI pin (Thanks for the update Samantha)

Connect the RSSI pin on the L9R receiver to the RSSI pin on the FCB. Only the signal wire is needed.

Configuration page - Turn Analogue RSSI On

Trouble shooting
If you are having problems getting the OSD information to show up in your FPV feed the issue may be your camera, TV standard choice or ground wire connection. 

Try swapping to a different camera. Some FPV cameras will not play nicely with iNav OSD and flight control boards.

Make sure you are consistent with your PAL or NTSC choices for camera, video transmitter and iNav OSD.

Make sure your camera and video transmitter share a ground connection.








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