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frsky xsrf40 review

FrSky XSRF4O Flight Controller Review and LUA Setup

FrSky XSRF4O Flight Controller Review

I freaking love the FrSky XSRF4O flight controller. It has so many features crammed on a 36x36mm board. Because it has an integrated XSR built in the flight controller, you can build your stack super low and clean.

  • F4 processor
  • Built in XSR receiver with SBUS and Full telemetry
  • BetaFlightOSD
  • SD card slot
  • Configurable LED pad
  • Easy to replace antenna wires

See the full specifications on the FrSky XSRF4O product page.

2018 Race Season

I get ask all the time what parts I’d recommend. The FrSky XSRF4o will be the flight controller I’ll be using in the majority of my race builds. It will be the flight controller EnvyAstro and SedHendo will be using in their race rigs for 2018 also. If a component can stand up to the abuse these two dish out then you know it’s freaking tough. In fact, we’ve been using this flight controller for the past 3 – 5 months and we’ve yet had one fail on us.

There are a lot of F4 flight controllers out there with built in BetaFlightOSD. There aren’t many that have a built in receiver. I love that because cause it eliminates one extra component that I have to worry about when building and anytime you can eliminate a component that just reduces the amount of solder points, one less component I have to find a way to mount and one less thing that can fail in a crash. It makes it able to build super clean also.


frsky xsrf40 reviewI won’t go into too deep on the build of the FrSky XSRF4O cause I’ll be using this flight controller in a PROton race build soon. I’ll just hit the highlights here.

The first time I used the XSRF4O I didn’t like it. It needs to be powered by a 5v source and VBAT needs to be connected to the battery so you can monitor your voltage. I wish they would have just made it be able to be powered directly off the battery. It’s more of an annoyance than a deal breaker. If you use an ESC with a 5V BEC and VBAT wire like the Spedix IS30 it’s perfect. What makes this ESC perfect to use with the XSRF40 is that the wire harness has wires for the 5V and a VBAT. This makes building super easy and clean.

LUA Script and TBS SmartAudio


I have the most badass readers. One of my readers Ringo showed me where UART3 is on the board. To enable the VTX portion of the LUA script, all you have to do is connect the SmartAudio wire from the TBS Unify to TX3. Then in the ports tab, enable SmartAudio under Peripherals for UART3. No need to remap the LED.

frsky xsrf40 review

Because this board has so many features built into it, there’s not a lot of room for extra peripherals, or spare UARTS. The XSRF40 doesn’t have any but no worries. Having the built in XSR it takes up two UARTS, UART1 is SBUS and UART6 is the SmartPort. It supports LUA script but to get the TBS SmartAudio working you gotta do a simple hack. You can reconfigure the LED pad to be used for the SmartAudio.

frsky xsrf40 review

Enable Serial and Telemetry on the Configuration tab:

frsky xsrf40 review

In CLI enter these commands:

resource LED_STRIP 1 none

resource SERIAL_TX 11 B06

frsky xsrf40 review

type “save” and enter

In the Ports tab, set UART6 under Telemetry Output “SmartPort” and for SOFTSERIAL under Peripherals select “TBS SmartAudio”

frsky xsrf40 review

frsky xsrf40 reviewIf your Taranis is set up with the LUA scrip, you can get full telemetry, PID tuning and VTX channel/band from the Taranis. To be able to change the VTX channel/band/power from your Taranis you need to be using the TBS Unify or ImmersionRC Tramp.

The retail price of the XSRF4O is about $50. I know what you thinking, 50 bucks for a flight controller? But if you break it down it’s actually not that expensive. It’s an F4 flight controller with a built in XSR. Compared to similar setup, a F4 flight controller such as the BetaFlight F4 which is $42 then you add a R-XSR receiver for for $20, that’s $62. So for less money and a much cleaner install, the FrSky XSRF40 is a hit in my book. Go try it out and let me know how you like it.

Check back soon as I’ll be using the FrSky XSRF4O in a PROton build post/video.

If you found this post helpful, it would be super cool if you purchased the components from my store or purchase items from my Amazon links. These posts are expensive and take a loooong time to make so the purchases make it possible for me to keep making them. Thanks in advance, I greatly appreciate it 🙂

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