Motor Noise comparison (0 min 46 sec)

3 ESCs were compared to find the least noise. None were as silent as a household fan, but SimonK at 18khz was the quietest.

After debating the issue all day, decided to go with the original plan of installing SimonK firmware.

An hour of intricate soldering attached a programming header directly to the Atmega8 SCK, MOSI, MISO, RESET. It had the same pinout as the Atmega328. This was a SuperSimple 15-18A from 2007, predating Arduino by many years. Atmel had yet to even label it as an Atmega.

The firmware was on https://github.com/sim-/tgy

Making the particular image required make tp.hex. There was also a tp_8khz.hex target, which generated 8khz PWM. tp.hex generated 18khz PWM. Installation used the Arduino as ISP sketch, using:

/amazon/root/arduino.heroine/hardware/tools/avr/bin/avrdude -C/amazon/root/arduino.heroine/hardware/tools/avr/etc/avrdude.conf -v -patmega8 -cstk500v1 -P/dev/ttyACM0 -b19200 -Uflash:w:tp.hex:i -Ulock:w:0x0F:m

The motor was now quieter than all the others, even at 19V. 19V at minimum throttle previously made the loudest squeel. There was still a slight wine from commutation, but the squeel was gone. It was quieter than the Castle Creation 35, which was rated at 32khz. The Castle still squeeled at 32khz, probably due to a bug.

There was a nugget on http://majek.mamy.to/en/hobbyking-su...monk-firmware/ about the tp.hex image containing a bootloader, but it required some fuse mangling & yet another Arduino sketch.

Hmm, but you are comparing the Castle on a different motor, and it definitely doesn't sound like 32kHz. If you'd like, you can try changing POWER_RANGE in my tree to try different PWM frequencies. It's software PWM, and the implementation skews a bit as a result, but it will let you set mostly any 16-bit tick value (interval) to get pretty much any frequency.