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Mar 23, 2018, 09:29 PM
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Writing esc firmware for the stm32 part two + it FLIES !


Everything is working as it should, I had one little glitch and blew up one motor in testing but the end result is a custom esc that behaves like an esc should. Responsive and fast. Next step is to make an interface to connect to the pc and change settings.
I am still playing around with different PWM techniques. One PWM pulse per commutation might be a good way to drive motors to very high rpms and avoid any phase locking. This means that pwm frequency will change as motor frequency increases. I am lacking very high rpms motors to test properly with though. Anyway that's for future posts.
It looks a little ridiculous strapping such a big esc on but, I couldn't wait to finalize the firmware or make a normal sized esc. I had to try it out on a quad. I forgot to change the throttle min to a normal range so it starts long before the other motors but that's a minor fix.
First flight with open 32 bit ESC on a quadcopter (0 min 58 sec)

First blog post without a schematic attached but i'll dig one up to put on tomorrow. The schematic for this speed controller is in my last blog post.
Last edited by AlkaM; Apr 15, 2019 at 08:59 AM.
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Mar 24, 2018, 07:25 AM
360 rodeo.
OrtisFlow's Avatar
Hey AlkaM,

I like your stuff and wondering what's the cost to make these escs.
Mar 24, 2018, 08:59 AM
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Originally Posted by OrtisFlow
Hey AlkaM,

I like your stuff and wondering what's the cost to make these escs.
The cost for a 32 bit esc goes something like this. USD.
stm32f051 = $2.50
mp6531 = $2.50
switching regulator and parts $1.20 or (linear reg under 20v 0.50)
caps and resistors about $1.00
Mosfets - $2.10 - $6.00 . This is what varies the most from 0.35 cents for a 2.4mohm mosfet to 1.00 or more for a nice 1mOhm. Price also goes up depending on the voltage requirement.
I get a whole bunch of different boards made out on one 10cmx10cm square so it works out to less than 50 cents per pcb.

So the end build cost is between 9 and 13 dollars depending on the power requirement and voltage. A bit more if you want to put a heatsink on for use in vehicle or high continuous current draw. This is the most expensive esc I have built so far but has the most capability. Most are around the 4-8 dollar range like the silabs based ones or the ones with transistor gate drivers instead of a chip. I think the cheapest 30 amp capable esc worked out to $3.50. I had a post on that a while back.
Apr 13, 2018, 09:18 AM
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4 flying stm32 dev boards betaflight proshot (1 min 55 sec)


Outdoor flight diy esc, Firmware version 1 0 (1 min 7 sec)


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