Comparison of SimonK and BLHeli 14.6 on an Afro30 ESC

Plans are being made to build another copter using a Seriously Pro F3 Flight Controller, and drive options are being considered.

Since this is a high performance flight controller with faster loop times, and Oneshot125 is used on the ESCs for faster response, an ESC that exhibits fast response is warranted to fully explore the benefits of faster loop times.

Most stock ESCs are quite slow, though with replacement firmware they can perform much better.

Though I have dismissed BLHeli for several reasons in the past, I have a set of Hobbywing Skywalker 40A Silabs based ESCs which will run BLHeli and not SimonK, so review of the current version (14.6) of BLHeli is warranted.

Dowloading 55MB of bloatware and updating the firmware using a Silabs Sticktool / C2 interface (which itself is quite fast and convenient as I have added permanent cables for the C2 interface), reminded me of most of the bad things of BLHeliSuite. Despite falling foul of the traps too many times, I achieved the desired result


This article documents some comparison tests of:

  • SimonK commit 1f75da384e5c83f83916aa752819ca6eed712565 afro_nfet.hex; and
  • BLHeli v14.6 for Hobbywing Skywalker 40A.

Continue reading Comparison of SimonK and BLHeli 14.6 on an Afro30 ESC

Dataflash on NAZE32

The Acro NAZE32 flight controller ships without a dataflash chip, which is so shortsighted of the designer / manufacturer. Many users will not be at all interested in Baro or Magnetometer which come on the deluxe version, but the dataflash is so useful in tuning a copter.

Unfortunately, the designer put pads on the rev5 board for 150mil SOIC-8 chips (SOICN), but lots of dataflash chips are in 208mil packages (SOICW) and all the large capacity chips are SOICW. Rev6 boards appear to have pads that will suit both sizes… but then the Acro comes with dataflash, even if small.

If you are happy to install a 2Mb dataflash chip, buy a SOICN package and your job is easy.

I installed a 64Mb Winbond chip (W25Q64FVSIG), they are easy to find on eBay for a dollar or so. (You will also need a 10nF ceramic 0603 cap).

If you want to install a SOICW package… Continue reading Dataflash on NAZE32

U-BLOX LEA-6T GPS module – for experiments

This article documents a LEA-6T module build for general experiments.

The LEA-6T is an inexpensive GPS module (~$40 at time of purchase, but getting cheaper) that can supply raw pseudo range data.


The module above is supplied for use on UAVs of various kinds, and came complete with a plastic radome and cables to suit an APM copter. The module also contains a 3D compass (magnetometer) which is not used here.


Above is the internals of the module with a custom cable to pick up just the RS232-TTL signals from the GPS (and supply 5V). The connector is a 8pin Hirose DF13. Continue reading U-BLOX LEA-6T GPS module – for experiments

Seriously Pro F3 flight controller gyro/acc failure

I purchased an Acro Seriously Pro F3 flight controller (FC) recently and having soldered the connectors on and loaded the current firmware, it was time for a pre-installation checkout.

The article outlines a basic pre-installation test that revealed problems that would prevent effective use of the FC.

Acc/gyro checkout


Doing no more than an acc calibration and allowing initialisation with a stabilised FC, the FC on the end of a USB cable should deliver acceptable sensor responses in Cleanflight Configurator (CC).

This flight controller has two problems:

  • offset in the gyro z axis (yaw);
  • low acc output in the Y axis (roll).

Continue reading Seriously Pro F3 flight controller gyro/acc failure

Flashing SeriouslyProF3 Cleanflight using ST-LINKV2


If for some reason you cannot use the bootloader that reads from the USB port via the CP2102, you can resort to programming the MCU chip using the SWD port and a programmer that supports that protocol.

WARNING: there is potential for damage if you get this stuff wrong. No warranty is offered, if you break it, you get to keep both parts.

Example hardware configuration


Above is the hardware configuration for programming. I have used a LiPo and BEC to supply 5V to the SPF3 board (the target), and a clone ST-LINKV2 (~$4 on eBay) is connected to the Serial Wire Debug (SWD) connector on the SPF3 with a custom cable. Note that you cannot use USART2 concurrently with SWD.
Continue reading Flashing SeriouslyProF3 Cleanflight using ST-LINKV2

Cleanflight – initialisation failure beeps

I spent quite a while chasing down a problem in a Cleanflight v1.13 flight controller which would not start properly, giving a series of beeps that one might expect hinted the problem.


Above is a scope capture of the /BEEP signal, five short beeps (50ms ON, 50ms OFF) then four long beeps (250ms ON, 250ms OFF). Continue reading Cleanflight – initialisation failure beeps

MultiStar 5200mAh 3S Lipo – initial tests

This article documents initial tests on a MultiStar 5200mAh 3S Lipo.

Two of these were purchased for about A$24 ea + delivery from the HK Australian warehouse.

On delivery, the batteries were served a balance charge to full capacity.

MultiStar52003SAbove, one of the batteries with the usual mods to suit my quadcopters. A heavy heatshrink encapsulation to reduce the risk of battery damage from crashes and flying propeller bits, rocks etc. A little velcro path to help stabilise the battery on the quad, a ‘gripper’ for the balance plug, balance plug secured to keep it out of the props, and a charge indicator for convenience.
Continue reading MultiStar 5200mAh 3S Lipo – initial tests

Lithium battery – 1S protection boards

Some of my projects use a single Lithium cell for power, and the ready availability of low-cost battery protection boards offers opportunity for better projects.

IMG_1472Above, a 1S board rated at 4A and which sells for about A$1 posted in lots of 5.


New and good quality
Use BM112 protection chip + AO8810 MOS tube
The protection board is used to protect the battery overcharge, over discharge, so can’t use as a charger,when you want to charge the battery you need to use the dedicated charger,because the protective board has a time to response to the short circuit, can’t to connect too large instant impact current, such as drills and so on

The main performance parameters:
1. PCB Size: 39 * 4 * 2mm
2. Overcharge protection voltage: 4.2750 ± 25MV
3. Over-discharge protection voltage: 2.88 ± 75MV
4. The overcurrent protection: 4-8A
5. Continue working current: > 4A

Note: Only for the equipment which instant start-up current less than 4A,those starting current instant is great, such as high-current motors, drills, etc., are not suitable for use.


Above are protected battery assemblies based on the board and a 1200mAh LiPo (sells for about A$4) and Panasonic 18650 Li-ion 3400mAh (sells for about A$12). The connectors used are 3A rated JST RCY connectors as used in RC battery applications and readily available with tails for way less than A$1 each set.

The 18650 cell has tags spot welded to the battery contact points, the LiPo has contact tags as supplied.

To use these, the power source needs to supply about 4.5V so as to ensure charging when necessary. The power source needs to be current limited unless you choose to depend on the protection boar’s limit.

RC PWM – ON/OFF switch

This article describes a remote ON/OFF switch which uses an RC receiver and adapter chip to convert the RC PWM signal into an ON/OFF output. (Suitable RC transmitters are on hand.)

The immediate application is for remote ON/OFF PTT or KEY of a transmitter for field strength testing at various locations.


Remote control hobbies have long used a multi channel digital proportional protocol for control of planes etc. The simplest multi channel receiver has an independent PWM output for each servo.

The PWM signal is a 1000-2000µs pulse with a repetition rate from about 50Hz up to 500Hz or so, the duration of the pulse conveys the information.


The converter chip is a ATTiny25 MCU with firmware that monitors the PWM stream and provides ON/OFF and OFF/ON output pins. For the immediate application, the ON/OFF (or non inverted) output drives a 2N7000 FET with ‘open collector’ output suited to the PTT and KEY lines of most modern transceivers.

The firmware ignores PWM signals with duration outside the range 900µs to 2100µs, and switches ON at 1600µs, and OFF at 1400µs to provide some hysteresis. If PWM input is lost for 125ms, the output will fail safe OFF.

rcsw01Above is the schematic. The 2N7000 is good for 60V, can handle up to 100mA without a heat sink, and had a body diode to absorb transients if the load is a relay. Continue reading RC PWM – ON/OFF switch