Chapter 8: RSSI Setup

Common receivers include ELRS, TBS_CRSF, and SIYI receivers. SBUS receivers do not provide RSSI.

RSSI is represented through a PWM channel.

ELRS receivers use CH15 to output simulated LQ signal quality, TBS CRSF receivers use CH12, and SIYI receivers use CH16.

Configure the RSSI parameter by searching for RSSI__TYPE in All Parameters.

ELRS receivers primarily use LQ to report signal quality, so select 3 for this parameter as shown above. For a SIYI receiver, select 2. Write the parameter, disconnect the flight controller USB cable, and remove power from the flight controller.

Reconnect the flight controller and search for “RSSI_CHANNEL”.

For an ELRS receiver, set RSSI_CHANNEL 15 and click “Write Parameters”.

For a TBS CRSF receiver, set RSSI_CHANNEL 12.

For a SIYI receiver, set RSSI_CHANNEL 16.

During radio transmitter calibration, the radio signal remains at full strength. Consequently, the maximum and minimum values may both remain at 2000 for ELRS channel 15, TBS CRSF channel 12, or SIYI channel 16. Adjust the minimum and maximum values for the relevant channel to ensure the correct RSSI feedback range.

The following example configures the ELRS RSSI channel, channel 15. Search for RC15 in All Parameters as shown below. For a SIYI receiver, search for RC16; for a TBS receiver, search for RC12.

Set RC15_MAX 2000 and RC15_MIN 1000.

The RSSI value for the corresponding channel will then display correctly during flight.

Testing with a SIYI FM30 RF module and SIYI receiver shows RSSI 99 when the radio transmitter is on. If the transmitter is switched off at the same location, RSSI may remain at 99; this behavior has no known workaround.

This does not affect normal range testing or flight. The displayed RSSI still decreases with distance and obstructions. In testing, with the aircraft indoors, carrying the display, radio transmitter, and FM30 RF module outside, closing the door, and walking downstairs caused RSSI to decrease progressively. Switching off the transmitter at that point changed RSSI to 0, automatically triggered failsafe, and activated RTL mode.