SP3 Racing F3

Preamble

I have killed my KK Mini flight controller by powering it up with the polarity reversed, see KK Mini, so I was in the market for another flight controller. I thought about simply replacing the KK Mini with another one, but could I get something better for my money as the KK Mini is rather a noddy affair. I saw the SP3 Racing F3 (also labelled as  the SP Racing F3), and thought that it might be worth taking a look.

I saw a cheap combo deal on eBay for a set of four 1806 motors (which I needs for my TL250A (see Drone kit -Building a Tarot Mini 250 (TL250A)) and a SP3 Racing F3 Acro, 4 x 1806 2280KV Motors + 1 x SP Racing F3 Acro for FPV Racing Quadcopter Drone, for £25.5o

There is also a third EVO version, see Oscar Liang’s SPRACING F3 EVO FC SETUP TUTORIAL and DroneTrest’s SP Racing F3 Evo Flight Controller Guide:

SP Racing F3 EVO
SP Racing F3 EVO

In addition, there is a smaller SP Racing F3 Mini MkII:

SP Racing F3 Mini MkII
SP Racing F3 Mini MkII

Confused? Well… there is also an even smaller (cloned?) version called the SP Racing F3 EVO brushed, which is for quadcopters only, as it has a reduced set of four ESC outputs, instead of eight:

SP Racing F3 EVO Brushed
SP Racing F3 EVO Brushed

As I already have a Naze32, I wondered what the advantages were.

you cannot use soft serial in the latest betaflight releases if you are using F1 flight controller due to resources limitation, it won’t arm if you do.

you can still use softserial for Smartport, but just means you cannot run 2Khz mode, and you probably have to stick with PID controller 1 (rewrite)

The SPF3 is pretty damn solid compared to the Naze32. It’s just the really weak connector system that let’s it down.

I been flying one for three weeks now without UART1. So no access to the FC for updates or tuning.
Done a pretty good job considering.
Check out the two videos I posted for a good idea of what the SPF3 can do even when damaged.

The reason to pick an F3 board has way more to do with convenience features than flight performance, unless to are running at 4 kHz gyro rate or higher. At the default of 1 kHz, there is literally no difference in flight performance between a Naze and an SP3. They even use the exact same gyro chip. The SP3 uses a faster processor, but it’s not actually doing anything different until you get above 2 kHz gyro rate.

Basically, the SPRF3 does what the Naze can do but better, faster and all at the same time with lower looptimes.

The SP3 is good but overpriced and the mini plugs on the board can come off in a bad crash! Check out the Seriously Dodo from Readymaderc. It’s cheap and runs the same hardware as the SP3.

Other F3 Links

Lumenier LUX F3 Flight Controller:

Good things about the LUX

Overall great quality flight controller board, Very well thought out, very well laid out. It’s very pleasant to install my electronics on it and not having to worry about too much where the cabling goes.

RX Pins and Solder bridges

very clever Radio receiver type jumper (between PPM and Serial – SBUS), you can just hook your RX up to the dedicated 3 pins on the board (RX signal, VCC and GND) then you are good to go.

You can select which type of receiver you want to run on the solder bridge on the back of the board. you can also select what voltage you want to power your RX, e.g. 5V or 3.3V by shorting the solder bridge.

Also this board powers the RX with USB meaning you can test your receiver without plugging in your LiPo battery, while your FC is connected to the computer via USB. It’s a lot safer.

Other good things

  • The 4 motor pins are at the four corners, so it cleans up your build substantially
  • It has a bootloader button to simplify firmware flashing
  • It’s using SPI Gyro so you can run 4 Khz mode (250 looptime) even 8 Khz mode (125 looptime)

Negatives about the LUX FC

MPU6500 Gyro

This MPU has worse noise spec than the MPU6050 or MPU6000 gyros that are used on some other boards.

You can tell in Blackbox, the traces just look noisier with this type of gyro. It really affects the tuning and how high your PID can go.

To fix that, you might have to turn gyro_lpf on (set gyro_lpf=188hz), and also set dterm_cut_hz=40 to clean up the traces and get rid of the noise.

Missing Softserial feature

It won’t run SoftSerial. Although it has 3 UARTs (serial ports), but if you need more serial ports than that, you won’t have it. Because they use the pin for the Gyro SPI.
For example you cannot run SBUS + Smartport telemetry + MinimOSD + External blackbox…. you will probably have to give up the OSD or Smart port telemetry as most people only use one of these.

No Flash memory chip
No flash memory, so you need external openlog SD card for blackbox

Features

There are two versions of the SP3 flight controller: the Acro and the Deluxe, with the deluxe having an additional MS5611 barometer and HMC5883 compass, source SeriouslyPro.

CPU comparison

  • The Naze32 has a STM32F103CBT6 @ 72 MHz (F1 – based on ARM Cortex-M3)
  • The SP3 has a STM32F303 @ 72MHz (F3 – based on ARM Cortex-M4F )

From Wikipedia – STM32:

STM32 is a family of 32-bit microcontrollerintegrated circuits by STMicroelectronics. The STM32 chips are grouped into related series that are based around the same 32-bitARM processor core.

See also Oscar Liang’s F1, F3 AND F4 FLIGHT CONTROLLER EXPLAINED for a run down as to the differences between the F1, F3 and F4 boards.

 

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