Review: CL Racing F7 Flight Controller

CL Racing F7 FC is finally here! I have been a great fan of the F4 so I cannot wait to check out their latest offering. The F7 maintains the same killer layout, and introduces a few pioneering features which we will go over in the review.

Learn more about mini quad flight controller in this article.

I just received the board, so I can’t comment on how reliable this FC is yet. But so far it’s been nothing but pure joy to build. The CL Racing F7 probably has one of the most logical and practical soldering pad layout I’ve seen!

Camera power, signal and control connections are at the front, while VTX connections are at the rear with jumpers to choose input voltage for the camera and VTX. All the pads are on the edge so there is no wires overlapping each other which often creates a huge mess that looks like a bowl of spaghetti.

This board is designed to be used with 4in1 ESC, so there is no integrated PDB. But you can also use it with separate ESC’s by using a dedicated PDB.

In the package you will find a cable for connecting 4in1 ESC, extra connector headers to match different 4in1 ESCs, and spare rubber grommets for soft mounting.

Beware that it doesn’t come with any standoff or nylon hardware, so make sure to get your own.

Here are the basic spec of the CLRacing F7:

  • STM32 F722 MCU
  • ICM20602 Gyro – Up to 32KHz Sampling Rate
  • BEC: [email protected], [email protected]
  • 2S – 8S Direct LiPo Input (up to 36V)
  • 1Gbit Flash Memory for Blackbox
  • VTX Pitmode built into to the FC
  • 6 UART’s
  • Reversed polarity protection
  • 5 Motor Outputs
  • Built-in Camera Control for OSD Pin

There are some pioneering features in this flight controller. Well I am not sure if others have done it before but this is certainly the first time I heard about them in a flight controller.

1Gbit Flash Memory?!

I personally prefer using flash memory for Blackbox, because it’s more convenient to use and doesn’t require an SD card. They also take up less physical space compared to micro SD card readers, and reduce the overall thickness of the board. But the 16MB flash chips on existing FC just aren’t quite large enough…

Introducing the 1Gbit memory chip on the CL Racing F7 flight controller, which is equivalent to 128MB, should be plenty for Blackbox log. Assuming if you log at 4K for 4 minutes each flight, 128MB should be adequate for 15+ flights.

FC Pitmode

Pitmode is basically a feature to turn down VTX power near zero when you are not flying, in order to minimize interference to other pilots.

Now the CL Racing F7 has this feature built into it, it allows you to turn your VTX on or off using a switch on the radio whenever you want.

Direct Solder Buzzer

I don’t know if it’s intentional, they leave just enough spacing between the beeper solder pads, so you can solder the buzzer on the FC directly without the need for extension wires.

Of course this is only possible if your frame has the space, but it’s such a nice touch!

Camera Control

By connecting CAMC pin on the FC to the OSD pin on your FPV camera, you can adjust your camera settings using your sticks! This was a pretty complicated thing to setup in the past, I am glad that CL Racing has it integrated.

I didn’t have to do any of the configuration, I simply soldered the OSD pin from my Runcam Eagle 2 to the FC and it just works!

Loving the layout, it’s so clean! The FC comes with the iconic yellow rubber grommets for soft mounting.

The pins are available on both sides of the board, which makes it flexible for soldering and wiring. The 1Gb flash memory chip is located on the bottom right, and is noticeably bigger than the 16MB ones.

The build quality appears to be top notch.

Make sure to check out the manual if you are building the CL Racing F7.

When connecting it to a 4in1 ESC, double check… no… triple check the wire orders! Even better, check each wire with a multimeter to avoid burning your FC.

When connecting Frsky SBUS and Smartport, don’t worry about inversion, any UART will work just fine. That’s the beauty of F7 compared to F4 🙂

Here is the official wiring diagram provided by CL Racing. Note that there is a mistake, they had TX1 and RX1 the other way round. Just follow the print screen on your board and you should be fine.

ICM series gyros was known to have noise issue, and everyone suggests using MPU6000 gyro for this reason. So why did CL Racing go with this seemingly “bad choice”?

Well, it turns out the noise problem associated with ICM gyro’s in the past was caused by poor hardware design – bad power supply to the gyro without proper decoupling.

CL Racing reassured me that they’ve eliminated this noise issue. I will report back once I have tested it.

The 128MB memory chip isn’t working yet in the current Betaflight release (BF 3.5.2). I have been informed that the support for this flash chip is only likely to be merged into Betaflight from version 4.0.

If you can’t wait, you can flash your board with their own compiled BF firmware, download here.

Unfortunately I had some problem with FC Pitmode. Since both of my FPV camera and VTX are powered by 5V from the FC, I think they must be putting some stress on the 5V BEC. Every time I flip the Pitmode switch to try to turn on the VTX, it causes the FC to restart and so the VTX fails to turn on.

After talking to CL Racing, they reckon the VTX draws too much initial current when turning on, and causes the 5V rail to drop below a threshold.

As an attempt to “fix” it, I soldered a capacitor (470uF) to the 5V pad and it worked! CL Racing is also looking to upgrade the 5V BEC from 1.5A to 3A in future revision.

It could be a VTX specific issue (I am using the OBVTX). If you have a different VTX, or you are powering the VTX from LiPo, you shouldn’t have this problem.


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