The current RSSI_PIN expects RSSI signal from 0V to 5V. The new FrSky X8R receiver has RSSI output signal with 0V to 3.3V levels.
It would be nice if the RSSI_PIN had option to re-scale (software re-scaling) the input level to 0-5 to get accurate readings.
if (RSSI_RANGE is 3.3) then RSSI = RSSI * 5 / 3.3;
This should require one additional RSSI_RANGE parameter and one or two simple lines of code.
As of now, the RSSI_PIN works with X8R receiver but when at MAX it obviously shows only 66% signal strenght.