AutoQuad ESC32 v1r5

Recently the Chinese ESC design utilizing the ATMEGA which we have been flashing with Bernard Konze's firmware has been disappearing from the market.  This was the push I needed to finally decide to design and build a replacement.  Collaborating with a friend, we worked on it over the summer.  It is finished and I think it came out pretty well.  I call it ESC32:


Design goals:

- Extremely fast implementation of requested throttle setting

- Ability to take high rate input

- Multiple input protocols

- Ease of programming, real-time debugging

- Efficient

- Inexpensive

The final specifications read:

- STM32F103 72Mhz MCU - 32bit ARM

- Firmware written in straight C

- SWD connector for real-time debugging

- Input via PWM IN / UART / I2C

- 1KHz PWM update rate capable

- All N-FET design with gate drivers

- At least 40A continuous with proper cooling, maybe much more

- 2S => 5S battery

- Option to power logic side via UART or PWM IN +5v

- Command Line Interface for testing / parameter modification / back channel

- 8KHz => 64KHz PWM out

- Current sensing / limiting

- Regenerative braking capable

- Closed loop control mode - experimental

- Lots of RAM and CPU cycles available for advanced control techniques

- BOM cost < $20 at quantity

3689435997?profile=original* image courtesy of TC Pictures, LLC.

It is a drop-in replacement for the ESC's that I have been running with AutoQuad and will take standard PWM input up to 450Hz.  I will eventually design new high rate PWM timing which will bring this rate up to 1KHz.  It is a definite improvement over the ATMEGA design.  Your flight controller can ask for large, quick changes in throttle and it is able to implement them very fast.  This allows PID output to be tuned to be more aggressive and results in much smoother control.

Start ups are very smooth and I have not yet found a motor it could not start.  It uses oversampling techniques which allow it to accurately control a BLDC motor down to 200RPM.  Early indications based on some initial head to head testing with other ESC's show the it is very power efficient.  This comes from the fast switching of the N-FETs due to the use of gate drivers.  Less time is spent in the on-off / off-on transitions, so less power is used, less heat generated.  No special heat sinks or cooling should be necessary for typical 10 to 20 amp usage.  This also means that you can use higher PWM output rates without too much of a hit to efficiency.

3689436019?profile=original* image courtesy of TC Pictures, LLC.

As the ESC is an extremely important component of multi-rotor UAV's, it is critical that it keeps running, no matter what.  So you can imagine the amount of testing necessary before you can start to trust a new design with your expensive machine.  There are a handful of people flying the ESC32 now and I myself have perhaps 10 hours without incident so far.  There may still be problems, but I am fairly confident that it is trustworthy.  It's all I fly now.

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  • @Max, thanks for that its the ESC themselves are always getting harder to buy (mostly out of stock). Been following that thread too..but thanks for the link. Just in my opinion if someone got an open source multirotor targeted ESC and ready for easy flashing it would be great oh and reliability is a big plus.

    Your video makes me want to just buy anything available now and just flash it :D

  • Cool look forward it being available
  • Developer

    That really cool, I'd like to try it :)

    @Jeff E Here is very easy guide on ESC firmware flashing   

    And video of my ACM with new firmware :) It so quiet !!!

  • I love the Bill's approach when something does not meet his needs. I will do my own :)
    Well done!!
  • Hi Bill, when you have it available for commercial sale, please let us know :)

  • Quite interesting to see this ESC. I myself is needing of an ESC that has higher PWM rates tho custom firmware is available its quite hard to get the reliable ones with the ready pin out for programming/flashing. Hope this is open source.

  • Developer
    Is escs done as opensource/hardware or closed? Yeah like Randy said. Pwm is a oneway workhorse. I2C a bit unreliable and uart has problems with port counts from MCUs.

    Old esc with quax and other firmwares are not dead, we are still working with those.

    Any price estimate for the escs?
  • very cool! Look forward for comercial avaibility

  • what about CAN interface?

    what is the enhancement in using an 72Mhz chip above an 16Mhz atmega?

  • Developer

    It's not mentioned but presumably the software is opensource and you'll make it available on github or googlecode or something like that? ..or maybe Bernard Konze's Quax code is a well known piece of ESC firmware that is readily available...

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