Ok, so here's the basic deal. The stock firmware coming on the ESCs works as intended but is far less than ideal for use in our quads. The problem here is that due to startup sequence timing from when you plug in the battery, each ESC has a microprocessor and code and so does the APM. The ESCs want to do some calibration when they first start and most of the time, the APM atarts it's code fast enough to send the right singals but it's a far less than ideal system. The truth is, we don't need a smart ESC. We need it to simply response to a known range of PWM from the APM and just run the motor. I presonally have seen the issues here in the forum and on my own equipment with the ESCs going into program mode and not responding because APM2.0 need you to press reset and then it boots whihc throws the entire start sequence into a wreck. THe problem again is usign off the shelf RC hardware designed to be used in all kinds of istuations where for the drones with the APM, we need one set of settings and that it.

Luckily for us, the community has done some hacking created some amazing firmware. Basically, a lot of the ESCs are from China and use Atmega 8 processors !! Most of them are clones on the same design with a different heatshrink or different form factor. The bottom line is that if you have the atmel based ESC, then likely, this will owrk and can remove 90% of the problems i have seen. I'll be the first to admit, it's a PITA to do it but after the first ESC and you verify it works, totally worth it.

My ESCs were from 3DR and they have the 3DR label and are rated at 20Amps. I also got some 30Amp ones from RCTIMER and they are the EXACT same board with a different stick and the 30amps have 3 more FETS that were missing on the 20 Amp version. Reports say that all three sizes from RCTIMER are the same 18, 20, 30, 40Amp are the same boards with more or less FETS.

SO, the good news is here are the combined instructions:

You need an AVR programmer such as Adafruit's usbtiny, or an actual AVRISP MK2 (or really any actual AVR programmer).

Some male to male jumper wires or pins

AVRdude and I used AVR burn o mat as the gui to make life easy.

Download the latest firmware from here as a zip file.https://github.com/sim-/tgy/downloads

I got the standard ICSP header  pinout (for the programmer side) from here http://www.evilmadscientist.com/article.php/avrtargetboards

This thread had the ESC info and flashing directions


FYI, both the 20Amp from 3DR and the 30 amp from RCTImer are exactly the same as the DYS 30Amp!!! It might as well be my own picture. Further, after you do one, rather than cutting the entire heatshrink off, you just cut a hole where the pins will be.

Just to be clear, here is the pic



After you get AVRdude downloaded and either follow the directions on the posting or use one of the tools to flash, you are good to go. The specific file used is tgy.hex as the new firmware for these ESCs that match the above picture.


Trust me, I flashed 10 ESCs today, 6 on the hexa from 3DR and 4 on the quad from RC timer and they are perfect. No more calibration BS, they just plain work. Due to removeal of some filtering code in the firmware, they also are faster to respond. No more BS, NO MORE CALIBRATION, just fly.

Can't believe somebody hasn't posted this before, the results are AMAZING. This firmware has been out for 2 MONTHS!!!!!



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  • Hello,

    so, I just flash this file "tgy_2012-03-21_6af38a2.zip" and that's it?

    My Jdrones 20A will be much better than?

  • Hi,

    I also had only good experience with SimonK firm. I have on my E-Flite 30A BLC, and my dirt cheap DragonSky's run like something 5 times the price.

    But do get controllers with a crystal or resonator clock source on them, this is much much better than the "ESC calibration" crutch.

    SimonK is an improvement (a vast one) of the earlier Quax firmware. There is no reason to experiment with that any more.



  • Developer

    If you plan to experiment with SimonK firmwares, this tool is worth every penny. No need to solder ICSP headers, just press the tool head over the chip and program.


  • There is a lot of enthusiasm for the Simonk firmware. Some of it warranted some not so much. Fact is you do need to calibrate them because of variances in the clock circuits from ESC to ESC even of the exact same type and brand. Latest versions of Simonk have the capability built in to do that and you do it the same way as the stock firmware - power on with the transmitter at full throttle, bring the throttle to zero and shut down the APM and then power up again. That allows you to calibrate all ESCs at the same time.

    So, why sometimes not so much? Well, you give up all safety features with Simonk. There is no over-amperage protection at all. The ESC with Simonk will simply burn up and maybe start on fire if too much current is drawn for too long. Also, no battery protection. It will let you run your batteries right down to zero. No auto slow-down or cut-off at all. Lastly, Simonk has problems with certain motors. Tiger Motors MT3506 for instance - it's not the only one. This motor is absolutely unusable with Simonk as are a number of others. Unfortunately, once you've flashed your ESC you can't go back and if you find out you've got one of the motors Simonk doesn't work on you are likely hosed - unless you've got the original firmward to re-load OR you could program up wii-esc firmware. It's another firmware for ESC that is based on the same original core firmware that Simonk based his on. The chief difference is the wii-esc really did the timing correctly and is not only able to programmed with correct timing so that motors like the MT3506 will work but it also has the capability to detect and recover from loss of timing events. Frankly, it delivers better performance than Simonk but is not as well known.

    Lastly, the Simonk firmware has been out a lot longer than 2 months. He's had many versions and the first of which were released early last year. And again, it's actually based on the work of another guy who get's no credit and, of course, none of the donations that everyone so eagerly gives to Simonk.

    I find it interesting how the Simonk thing has taken on an almost fanaticism aura in the community and especially since there are actually some other, better solutions.



  • Sorry, double post due to weird browser error?????

  • Attached now are the original 3DR and RC TIMER 20A and 30A (probably the exact same but haven't done a "diff" to check) original firmwares to backwards flash in case you messed up or want to compare performance between the upgrade "hack" firmware and stock.



  • To be fair, this has been mentioned before DIYD.

    If people are going to try this out themselves, I can recommend the HobbyKing F20A. It's got an on-board resonator so has an accurate clock, unlike other ESCs which rely on the inaccurate oscillator built into the Atmega. Also, the programming pins are all in a row which makes reprogramming them MUCH easier. They have the more efficient all N-FET design, and they are one of the cheapest ESCs to boot.

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