Why Use XM+ Plus Receiver for Taranis?

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.

Get your Frsky XM+ receiver from http://bit.ly/2nx0pe6

For more information about RX, check out our list of Frsky radio receivers for mini quads.

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.

XM+ Frsky RX Radio receiver PCB top XM+ Frsky RX Radio receiver PCB back

Frsky SBUS receiver size comparison - XM XM+ XSR X4R-SB

Credit: http://imgur.com/Jo56aKV

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.

  1. Size and Weight are different
    • XM – 15.0×10.0x3.5mm – 1.0g
    • XM+ (plus) – 21.5x12x3.5mm – 1.6g
  2. The XM+ has Diversity Antennas (2 antennas), XM only has 1 antenna. Diversity antennas gives better range
  3. 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

22 thoughts on “Why Use XM+ Plus Receiver for Taranis?

  1. Frank

    Hi,

    i accidently tried to flash the wrong firmware.
    Now i it is just impossible to flash any firmware on my xm+. Allways get failure message.
    Any advice on this?

    Reply
  2. Chris Young

    Oscar, when using RSSI on ch 16, is it necessary to do any calibration? It would seem that any PWM value 2000 reads 100%. Everything else is in between but there must be a need to calibrate this?

    Reply
    1. Oscar Post author

      no the RSSI on ch16 is a PWM signal not an analog signal, so your FC is probably not seeing the signal correctly.
      You might need a ADC to convert the signal to anaolog signal first before feeding it to your FC.
      Or you can do this hack

      Reply
  3. Adam K.

    Oscar, I have done a lot of range testing with my x4r-sb and these XM+ antennas, and I’m happy to say that I actually get much better range with the XM+! I thought it was a fluke, but after putting 5 xm+ receivers on my quads they all perform the same. I have a test field that I fly, and 1,500 feet out my x4r-sb is getting in the low 70s for RSSI, while the XM+ is still in the mid/low 90s. I don’t really understand how these are getting a good amount better range, but it’s great. Just thought I would share with you and others that read this website!

    Reply
    1. Paul

      I’ve flashed 2 xmplus with latest firmware both 16 and 8 channel for non LGBT.
      And I am getting the worst signal ever.
      Only about 10meters and the quad drops from the sky.

      I’ve tried my x4r and that completely works a treat no drop outs.

      So confirmed it is not the radio.

      Could someone help shed some light on this please?

      Thank you.

      Reply
  4. Alex

    I get a green light after binding but wont arm. was working before on old receiver. Fc is kombini and using a passado osd. do you have any thought on what to check?

    Reply
    1. Oscar Post author

      this is one of those common problem, try to Google it first. But here are a few things you can check:
      – check receiver tab activity
      – check if you have the correct configuration setup for RX

      Reply
  5. fl0PPsy

    Being able to adjust PIDs, Rates and VTX settings over the S.Port link makes not having that feature a big fail for these receivers.

    Reply
    1. Oscar Post author

      like I said in the title, it’s great for micro builds, where space and weight are constraints. Anyway it’s great too on bigger builds if S.Port is not needed.

      Reply

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