The XM+ radio receiver is a tiny SBUS diversity RX from Frsky. It’s insanely light weight making it a great alternative to X4R-SB and XSR RX for micro quad builds. In this post we will show you the features of XM+ and how to use it.
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What are the advantages of XM+ receiver?
- Much smaller size and lighter weight than X4R-SB and XSR
- It’s a full range receiver, similar range to X4R-SB and XSR
- Using same antenna/connector as the X4R-SB, replacement is very easy
- It’s possible to direct solder RX to FC with header pins without wires (if FC supports it)
- Only 3 pins: Vcc, GND and Signal – there is no confusion
- XM+ is even smaller than the LR1000 by FuriousFPV, great RX option for their micro quads (such as the Moskito70)
Only downside of XM+ RX is the lack of S.Port full telemetry (Smart Port), there is only RSSI telemetry. RSSI has a dedicated solder pad and it’s also available on the 16th channel.
More info on XM+ RSSI Output
For those who would like to display RSSI in OSD.
RSSI pin outputs PWM signal (0-3.3V). Please be aware that this signal should not be connected to MinimOSD directly, as it will give you 0% or 100% only. You will need a digital to analogue converter (low pass filter) to convert PWM to analogue voltage level.
However the XM+ can output RSSI through Channel 16, so in Betaflight/Cleanflight should be set to use CH16 for telemetry signal and limit aux channels to 12.
Binding and Failsafe
Binding and Failsafe Setup process is exactly the same as other X series Frsky Receivers:
Red LED on RX means it’s not bound or not detecting TX. To bind, enter Bind mode on TX, hold down F/S button on RX and power on. After a few seconds, Green LED will light up indicates binding has completed.
To setup up failsafe, power on both TX and RX. Set your TX channels to desire positions, and press the F/S button on the RX. The green LED should flashes and indicates F/S has been setup. Please confirm if F/S is now working as expected by turning off TX. To remove F/S, simply rebind the RX.
Differences Between XM and XM+ (plus) versions
Both are SBUS receivers, but there is some differences between the 2 RX.
- Size and Weight are different
- XM – 15.0×10.0x3.5mm – 1.0g
- XM+ (plus) – 21.5x12x3.5mm – 1.6g
- The XM+ has Diversity Antennas (2 antennas), XM only has 1 antenna. Diversity antennas gives better range
- Slightly different input voltage:
- XM – 3.5V-10V
- XM+ (plus) – 3.7V-10V
RX is bound, but not getting signal in FC
One common problem getting SBUS to work: RX is bound to TX (solid LED on RX) but not getting signal to FC (no activity in receiver tab).
- Make sure TX is in D16 mode
- Some FC has built-in SBUS inversion, some don’t. Try setting SBUS inversion on or off, it normally fix it.
set sbus_inversion = on