Review: Betaflight F4 Flight Controller

by Oscar

Anyone who uses Betaflight should be familiar with the Betaflight F3 flight controller. FPVModel has just upgraded it and put a F4 processor in it. In this review we will also check out other changes.

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The Betaflight F4 flight controller is now available at FPVModel. To learn more about flight controllers, here is our guide.

Unboxing and Features

The Betaflight F4 FC comes in a plastic box, with only the board itself, and a 10cm servo cable. It would be nice to see some low ESR capacitors or even soft-mount rubber bobbins included.

  • F4, MPU6000
  • Integrated PDB
  • Betaflight OSD
  • Current Sensor (up to 145A)
  • Flash Memory for Blackbox
  • 5V / 1.5A BEC
  • Supports 3S, 4S, 5S and 6S LiPo battery

Betaflight F4 VS F3

Let’s compare the new and old Betaflight boards, here is our review of the Betaflight F3 FC.


The board layout and dimension are nearly identical: the motor output pins, UART’s, camera in/out etc…


The biggest change seems to be the processor. They’ve also used a lower rating but reportedly more reliable 5V BEC. It comes with BLHeli32 ESC Telemetry pads (RX1 between motor output and GND). Finally they replaced the SD card slot for Blackbox with a flash memory chip.

However just like many other F4 flight controller, you have to perform the uninverted Smart Port hack to get SPort Telemetry to work. It’s not a hard thing to do, and the latest R-XSR receiver even has a breakout pad for easy soldering.

Here is a table to summarize the changes:

Betaflight F4 Betaflight F3
Processor STM32 F405 STM32 F303
IMU (Gyro) MPU6000 MPU6000
BEC [email protected] 5V@2A
ESC Telemetry Pad Yes No
Blackbox Medium Flash Memory Micro SD Card
Price $45 $43

Why Betaflight F4?

F4 is a more powerful processor than the F3 (for detail differences between different STM32 processors, check out this post).

But is it worth the upgrade for existing Betaflight F3 users? I would say it depends heavily on how much you care about running the fastest looptime and the latest BF features. For new buyers, it’s a no brainier to get the latest F4 boards.

Since the release of Betaflight V3.2, we started to see many F3 FC users complaining about high CPU usage. This is mainly caused by the new Dynamic Filter feature, which is too much for F3 processors. F3 users have been asked to lower their looptime from 8K to 4K when running Dynamic Filter.

Therefore if you want to run the fastest possible looptime (i.e. 8K/8K) with Dynamic Filter on, more powerful processors like the F4 is the way to go.

Notes about Smart Port and SmartAudio

FPVModel suggests using Soft Serial for Smart Port Telemetry and SmartAudio, but I found that it’s not necessary to use Soft Serial, both can be setup on normal UART’s just fine.

However, I was having problem setting SmartAudio on UART1’s TX, I even try setting UART1’s TX pin as soft serial still no joy.

UART2 just doesn’t seem to work for either Smart Audio or Smart Port at all, with or without Soft Serial. Just very odd issues I have no clue why.

In the end I had to put Smart Port to UART1’s TX, and use UART3’s TX for SmartAudio. This is the only combination that works for me.

Update about UART (16 Nov 2017)

So I couldn’t get UART2 to work at all for Smart Audio and Smart Port, and it turns out UART2  has inverter on both TX and RX.

You can use UART2 for SmartPort with some modification: you will need to get a small signal schottky diode connecting TX to RX, and connect Smart Port to the RX. And turn off tlm_halfduplex in CLI

I have also successfully setup Smart Audio and Smart Port using soft serial on both UART1 and UART3. Make sure you power cycle the flight controller and TX, it didn’t work before probably because I didn’t do that.

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Bob Anderson 6th September 2019 - 2:10 am

Is there A way you can look at the Noxe f4 flight controller. It will not read voltage and I have many of these with the same problem.Running latest Betaflight and hrc 15amp 4×1 esc unable to get voltage read on osd or even in Betaflight.

Matthias 29th January 2019 - 9:49 am

Hello Oscar

I decided to use the Betaflight f4 Fc as I´ve heard it should be easy to set up. Unfortunately I have a problem and can not find a way to solve it.
The problem ist “RXLOSS”.

I checked the following steps:
1. The wiring on the FC. I have soldered the receiver to GRD, 5V and the signal wire to DSM2 SUMD.
2. The binding between my Graupner Hott mx-20 and the Graupner GR-12L SUMD+T Diversity Receiver. It works.
3. The I connected th FC to the Betaflight configurator. By default it showed on UART 6 Configuration/MSP to OFF and the Serial RX to ON.
4 On the configuration tab I selected the receiver mode to serial receiver SUMD as well as the receiver to SUMD.

After turning the transmitter to on and powering the FC with the S4 Battery I could not arm the FC.
The STATUS in the CLI of the configurator tells me always RXLOSS.
Meanwhile I tried Serial RX of UART1, UART2, UART3, UART6. No succesess.

Do you have any idea to solve my problem?
Could you please explain when to select which UART?

Best regards,

SpeedyReedy 26th March 2018 - 12:04 am

Hi Oscar, Can you please do a post explaining how to setup soft serial on UART 1 and UART 3 for this board?
either that or a post on how to wire-up FPort on the BFF4 board.

“I have also successfully setup Smart Audio and Smart Port using soft serial on both UART1 and UART3. Make sure you power cycle the flight controller and TX, it didn’t work before probably because I didn’t do that.”

Oscar 1st April 2018 - 12:46 am

I don’t have the board anymore… And there are other boards I like better so it’s unlikely i will get another.

Jake Shelhamer ( Team DV8 Pilot) 8th February 2018 - 5:00 am

Hey I get to comment on something on this awesome page because i’ve actually tested it and i don’t see another like it.

I’ve built my xClass rig with a BFF4 and i’m running 4000mah 6s on it, flew it multiple times without any issue. I’m only powering the RX and the Camera off of the BFF4 and my TBS HV VTX is powered elsewhere. I can confirm it runs 6s without and issue.

Useri 29th December 2017 - 2:15 pm

Hi Oscar, can you figure out the battery voltage? my BF F4 the voltage show 6s to 7s battery voltage. the setting are default.

Mike stevens 14th December 2017 - 3:12 pm

I have been having a video issue with one of my betaflight F4s that I cannot figure out. I am to the point where I think I either have a bad pin in the board or it’s something extremely stupid that I’m not catching. When the runcam is connected to the video in port I get no video but perfect grey screen and OSD. When I connect the camera straight to the unify I have perfect video. I’m using 5v to power the camera, but also tried it on vbat with no luck either (with the addition of a lot of noise since it was an unfiltered connection just for testing.)

John 5th February 2018 - 5:55 pm

I have the exact same issue. I can’t seem to figure out what is wrong. Any luck with this?

John W 19th March 2018 - 4:21 am

I had this exact issue also. What i ended up doing was using a external BEC to power the camera it appears that i wasn’t getting enough power on the onboard to run my cam. Hope this helps.

Mike 14th December 2017 - 11:39 am

Hi Oscar,
Great runthrough thanks.
I am in the middle of a couple of builds using F4 boards and trying to get Unify Pro HV Smartaudio working with sound from an Arrow V3 camera but really struggling. I have followed the wiring diagram set out by TBS incorporating 100nf, 4.7k and 1.8k but no joy. They work independently but not together. I have tried on Uart 6 but not softserial yet. Would you have any advice on this?

usama khurram 6th December 2017 - 5:44 pm

Is it work for big frame size 600mm.. which has a payload of 3kg?

Tim G 4th December 2017 - 6:11 pm

Hi Oscar, does it matter which end of the diode is connected TX and RX on UART 2?

Oscar 12th December 2017 - 1:37 pm

yes it matters, current/signal can only go through a diode one way. You should place the diode in a way so the signal from TX and go to RX pin.

Robin 26th May 2018 - 10:05 am

I still didn’t get that diode part. Can someone explain me?

Tim 4th December 2017 - 1:36 am

Out of all the info you listed nowhere does it say what the max input voltage is. 4s? 5s? 6s? Thanks for all you do btw.

Oscar 4th December 2017 - 4:32 pm

yes you are right, I just added the info.
It supports 3S to 6S according to FPVModel, but we have only tested 4S on this board.

Ringo 27th November 2017 - 7:56 pm

My 5V Buzzer do not work at the Buzzer-Port.
Have always 5V potential between + Buzzer port and Ground but never against the – Buzzer Port.
Anyone the same Problem?
In Betaflight i can see the comand with my aux2 channel is incomming and the red led do flash quickly but nothing happend with my buzzer.
All Buzzer options are on, the USB option too.
Any idea?

patric 8th December 2017 - 1:33 pm

I have the same issue as you, but also not a solution till today :-(
Now I am using the motors as a beeper, but the beeper would be louder and can be used during the flight. If someone has a hint would be great.

Tomas Avila 28th January 2018 - 5:26 pm

I also have the same issue. Did anyone figure this out?

s3npai 21st November 2017 - 7:12 pm

Will this one have enought UARTS available to run SBUS/Telemetry/SmartAudio/Runcam split(needs both TX and RX)? UARTS always confuse the heck out of me!

Oscar 28th November 2017 - 2:04 pm

yes, there are 3 UART’s, and 1 dedicated Sbus input, so that should be enough.
If not you can still use soft serial to utilize LED port :)

JamboFPV 15th November 2017 - 2:18 pm

I am getting pretty bad video with a lot of noise, I am using Foxeer Arrow V3 and a Tramp HV. I have tried wiring Cam to 5v which seemed to not provide enough power and now am powering direct from the batt +. I am also using a capacitor across the batter connectors. I am thinking of just running to run video directly from VTX to cam.. which kind of sucks because one of the reasons I wanted to try Betaflight is OSD. Any Ideas?

Oscar 18th November 2017 - 7:44 pm

Make sure you wire the ground of VTX and Camera to the “AGND” pad on the FC, thiis extremely important to get clean video.
You can power the VTX from batt+, but you should power your camera with the 5V from the VTX.
I would also put low ESR capacitor on the power or ESC’s if possible.

Dylan 4th December 2017 - 7:00 am

Does that literally mean to solder the vTX power wire straight on top of the positive lead for your XT60?

Oscar 4th December 2017 - 4:42 pm

depends on your VTX’s input voltage, if it supports the battery voltage then you should be able to connect them directly.
But I usually avoid doing that and power my VTX/camera with regulated and filtered power

Dylan 4th December 2017 - 9:02 pm

I have the TBS Unify Pro HV. The wiring diagram shows the vTX to be powered by vBat if I’m reading it correctly. I wasn’t sure if that literally mean to solder the vTX power wire to the same pad as the XT60 positive wire.

Here is the diagram.


Oscar 12th December 2017 - 1:41 pm

yes you can, the VTX is rated for 6S input. But i am just saying that’s not the best practice.

avinash nk 9th November 2022 - 12:12 pm

Dear sir, i am a layman in this filed, hovever i ve got a fpv frame (carbon fib)motors fc may be beta flight f4, vtx tbs uni pro, 5G8, rcvr tbs crosfire micro..this is all i ve(found in scrap) transmitter, could u pls suggest cheap n best tx for above setup ?for beginner ?

Totostao 29th October 2017 - 11:20 am

I’m using a unified TBS unify RACE, and the new FC BetaflightF4 and when I connect everything as indicated in the diagram I have the problem of not being able to see the osd, but when I disconnect the camera the osd works perfectly. How can I fix it?

BigMushyPurples 31st October 2017 - 10:25 pm

Sounds like you need to make sure you’re running NTSC or PAL (depending on what you support).

Charlie 3rd November 2017 - 2:48 am

second relpy, after a little more research. I didn’t have my camera set to the correct format, I think it was on ntsc and needed to be on pal

Charlie 3rd November 2017 - 2:14 am

I’m having the same problem, right down to disconnecting the camera and osd shows up :) I hope we can figure it out

Brian Wright 29th October 2017 - 3:04 am

I just got mine wired up but haven’t flown it other than hovering in the basement yet. The dataflash chip on mine appears to be bad. I double checked and I didn’t knick or short anything while soldering. The configurator couldn’t put the board into DFU; I had to use the boot button. I flashed 3.2.1. Configurator still can’t put the board into DFU. I’m curious to see if anyone else had that issue or if I got an unlucky manufacturer defect. Soldering was relatively easy, but the grounds for the ESCs do seem to soak up heat. I’ll report back if anything significant comes up while flying next week.

BigMushyPurples 31st October 2017 - 10:28 pm

I’ve had a number of FC’s boot button go bad on me and was preventing me from flashing via DFU. I was able to bridge the two boot pads with tweezers bypassing the button all-together. Doubt this would be an issue with a brand new board, but just sharing my experience with previous BF F3 boards.

Brian 6th November 2017 - 8:12 am

It’s been a week. No problems to report. My data flash chip started working randomly a couple of days ago after a decent crash. I suspect the factory soldering is faulty and the crash restored connectivity. Everything else seems to be performing well. I’m running 8k/8k and it’s not pushing the CPU at all. So far I’m pretty happy with the purchase. I wish it had a dedicated FPV camera control pin so I didn’t have to choose between LEDs and that.

Brian Wright 9th November 2017 - 2:11 am

The dataflash chip isn’t working again. I started get noise on the analog ground in my fpv feed. I swapped the ground on the 5v row below it and that fixed the issue. Still working very well. I was able to turn off all my static filters today and the quad flies amazingly. I think I like this board much better than the DYS F4 Pro I was using before. If the dataflash worked it would be perfect. I haven’t tuned this quad and I’m still using stock PIDs but when it comes time to tune I’m sure I’ll wish I had the blackbox.

Matt 27th October 2017 - 3:45 pm

All of my BF F3 boards started having critical failures at the same time, possibly due to CPU usage and possibly due to BEC failures. I have since upgraded all my rigs to BF F4, initially there were some really awful mid throttle oscillations, really really terrible. I did the PT1 Lowpass Filter and incrementally eliminated notch filters checking motors each time (I was worried the oscillations were bad noise). These changes made all the difference, went to butter smooth flight and motors come down cool to slightly warm. Utilizing Quadrant_32 ESC’s or any other 4in1 ESC is non trivial if you want to use the on board current sensor, also the motor pins make for a less than clean build for a 4in1. My next build will probably use the Betaflight ESC’s to check out that goodness. All in all I really like the FC though I will need to put it through its paces before I could decide if its long term tough.