Malenki-ESC open source Antweight ESC

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MarkR
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Malenki-ESC open source Antweight ESC

Post by MarkR » Tue Mar 26, 2019 11:11 am

Hi,

I've designed an open-source hardware Antweight ESC.

It is still under development, but I now have my first actual board made. It doesn't work yet because the firmware isn't finished.

* Three channels of DC motor drive (maximum current TBC, but should be at least 2A)
* Takes PPM/CPPM/ i-bus (and maybe S-bus) single wire signal from a RX (like drone controllers do)
* Open source hardware; open source firmware.
* Almost as small as a Dasmikro (about 24x26 mm)

I will post more information later. In the mean time,

Source code is here: https://github.com/MarkR42/malenki-esc

Image

Schematic: http://vectrex.org.uk/mark/esc-marketin ... ematic.pdf

PS: apologies for installing R2 upside-down, all the electrons will fall out :) - I will do it the right way next time.
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Re: Malenki-ESC open source Antweight ESC

Post by MySolderIsOlder » Tue Mar 26, 2019 12:16 pm

This is VERY exciting (or should I say 'ochen volnuyushche') news, Mark! Support for cPPM would make life so much easier, especially if/when HK ever get the OrangeRx R614XN back in stock. Best of luck finishing it off.
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Re: Malenki-ESC open source Antweight ESC

Post by LimaHotel » Tue Mar 26, 2019 3:12 pm

Now THAT looks exciting! :D
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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Fri Mar 29, 2019 10:00 pm

Now I have a strange issue.

I've got the ESC working and decoding PPM signals. They seem to work ok, my receivers will stop sending pulses when they lose signal, and after a short time then we turn the motors off (as you'd expect) to implement failsafe.

I'm now working on supporting serial protocols such as Flysky/Turnigy i-bus.

But using the Flysky I-bus protocol, the Turnigy iA6C (this one) continues sending pulses (with the sticks in their last known position) even after the transmitter is turned off.

This would be really inconvenient and violate the rules, because we can't implement failsafe, a spinning robot could keep spinning until its battery ran out.

I've got another receiver which is the Turnigy FS-A8S which doesn't exhibit this problem.

I'm guessing that the "smarter" telemetry rx is trying to be clever, or waiting for telemetry from the drone it's in (good luck) before it stops sending packets.
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Re: Malenki-ESC open source Antweight ESC

Post by Kyro » Fri Mar 29, 2019 11:57 pm

menu, rx setup, failsafe... play with these settings... may help with your issue...

works only for the afhds 2a as the regular afhds seems to do it automatically if signal is lost
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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Sat Mar 30, 2019 2:30 pm

Update:

What works/ is done:

* The motor drivers work. I've tested it with a spare N20 and it can drive it with no problem at variable speed in both directions.
* Tank-mixing
* The receiver can automatically decode PPM signals or ibus (Turnigy)
* I wrote some end-user documentation

What is still TODO:

* Decoding S-Bus signals (S-bus uses a different serial speed, inverted signals and requires some bit-twiddling)
* Make a better programming / testing system - because right now I have wires soldered on to surface mount pads
* Build a test robot!
* Fully document the hardware (BOM, assembly instructions, PCB manufacture notes)

I have made some very minor revisions to the PCB for the next batch to allow easier assembly and update the silk-screen.

If anyone is interested, the hardware design and firmware, etc, is all here: https://github.com/MarkR42/malenki-esc
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Mon Apr 01, 2019 4:08 pm

Another update:

* Firmware is mostly working, it reads PPM, ibus or S-Bus and will autodetect (there is only one rx pin)

I intend to build a robot with it shortly to see if it will actually bot :)

Here is a size comparison, left to right: £1, DasMikro2S6A (2-channel), Malenki-ESC (3-channel), €1

Image
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Re: Malenki-ESC open source Antweight ESC

Post by Paulmchurd » Thu Apr 04, 2019 6:51 pm

This looks awesome, however I’m a little confused. Does this only work through a single signal wire?

All 3 Signal wires are through 1 wire??

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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Fri Apr 05, 2019 9:06 am

Yes, there is only one signal wire.

Drones commonly use this, the signal wire speaks one of several commonly used protocols, either CPPM (which is several PWM signals multiplexed in time) or one of the serial bus protocols S-Bus or i-bus.

It allows more channels with fewer wires. I can incorporate more than three channels, for example, channel 5 I used as an invert switch in case the robot is upside down.
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Re: Malenki-ESC open source Antweight ESC

Post by LimaHotel » Fri Apr 05, 2019 4:12 pm

So how does that work with regards to wiring it into a receiver?
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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Fri Apr 05, 2019 5:03 pm

There are three wires to connect. Two for power, and the third carries signals for all channels.

Typically there's a dupont connector with three pins, gnd, power, signal. This is mechanically same as a servo, except it is electrically different. The ESC provides power to the RX (just like the Dasmikro, etc)

Look at your rx manual. In some RXs the "bind plug" doubles up as a PPM or serial interface.

During testing, I used Turnigy / Flysky receivers, incuding this one

https://hobbyking.com/en_us/fs-a8s-2-4g ... tore=en_us

Which is incredibly tiny and light - it has a tiny little connector but comes with a lead that has normal 0.1" dupont connector on the other end.


If you look at this product picture (Hobbyking)

https://cdn-global-hk.hobbyking.com/med ... 5267_1.jpg

You'll see the type of connector. The yellow wire is for PPM, the white for ibus / sbus, and the red/black carry power. You only need the yellow *or* white, not both, so could snip the yellow (I prefer the ibus as it's fully digital and gives the values in microseconds-equivalent-pulse).

Flysky transmitters have an option in the menu to tell the rx whether to use ibus or sbus - they use the same pin but not at the same time.

Sbus is used on other brands of rx too, for example on the Frsky stuff. I haven't tested it yet because I don't have one, but I expect it's very similar.

EDIT: Update: unfortunately the Malenki-ESC is not working too well, it runs ok off USB power or a bench supply, but Lipos seem to sometimes make the microcontroller go pop, I think I need to change the power circuitry.
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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Sat Apr 13, 2019 10:14 pm

Hi,

It seems the Malenki-ESC is now working a lot better.

* It does bot :) - I've built part of my next bot and it's driving just fine with 2 N20s.
* I solved the voltage regulation problem which caused 2 mcus to be destroyed

If I make a *small* number of these boards, does anyone want to test one? I can probably ship them out for about £8 (NB: This is the prototype price, there is no guarantee that they could be volume made for this price)

I will need to order some parts soon, so I'm trying to gauge interest.
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Re: Malenki-ESC open source Antweight ESC

Post by LimaHotel » Sat Apr 13, 2019 10:23 pm

Would absolutely be interested in trying one - what kinda rx would I need to make the fancy 1 wire signal thing work? I usually use lemons, do you know if their bind pin would support it?
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Re: Malenki-ESC open source Antweight ESC

Post by MarkR » Sat Apr 13, 2019 10:40 pm

Do you have a link to the datasheet?
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Re: Malenki-ESC open source Antweight ESC

Post by Kyro » Sat Apr 13, 2019 11:20 pm

i may consider one... but R2 would definitely have to be the right way up... i cannot afford to lose any electrons ;)
Team Rocket Robotics
Esper(4wd flipper)
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Dominus (SPINNAAAAAH under construction)
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I got in touch with my inner self today....... Thats the last time i buy cheap toilet paper!!

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