or, in what case does the ESC lose its calibrations or de- sync?

The problem is this:  my Hex's ESCs have simonk firmware, and don't seem to hold calibration for very long. Granted I'm not an expert here and haven't yet flown a great many hours with this copter, but something has caused calibration to be lost in one or more ESCs over time, several times. ALL-at-once re-calibrations NEVER have worked reliably, necessitating calibrating them separately.

I guess i want to know if this is a process that should be included in every preflight or should I reasonably expect it to stick? Or am i obviously doing something that causes re-initiation other than the documented high throttle init?

Does everyone re-calibrate before each flight?

Thanks in advance, as always,


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Bart, The short answer is 'No. Everyone does not recal ESC before a flight.'

The usual problem is making sure you have good cal to begin with.

Are you familiar with the CLI mode in MP (mission planner)?

I ask because there are several useful tests there that could help diagnose your issue.

Also getting familiar with looking at the log files helps..at least being able to post the *.log file here.

It will also help us to know which APM you are using and your TX, RX brand.


Check if your ESCs have external oscillator (ESC specs). You want ESCs with external oscillator , the Atmel's internal oscillator is not accurate enough to sync several boards together and its frequency will vary with temp.

Internal oscillator ESCs do work, but need recalibration much more often.

I use the CLI a lot but there's plenty there im not very aquainted with, so any direction you could give in that regard would be immensely helpful. For what it's worth Im much more comfortable now knowing that i have a good calibration that has solved some other issues ive been experiencing. FOr some reason the all-at-once methodology has rarely worked for me, as opposed to 100% success rate with getting the APM outta the way and directly and singly calibrating them. Im stiill a newb so some behaviours still catch me by surprise. I havent really had it in the air since converting from quad to hex, but it could all be due to that. Hopefully i can try her tomorrow if winds are light.

I should make a sig with my setup.... sorry about that.

  • HEX - Cobbled frame yet light CF/Ply/Alum < 500g ( not Coax Y)
  • APM 2.5 /2.8.3
  • DIY Drones  stock 880kv (A-2836/9) -unsure of OEM, turnigy maybe
  • DIY Drones stock 20amp Yellowrap ESC- reflashed with simonK- unsure of OEM
  • 12 x 4.5 APC
  • 6ch DX6i spektrum TX
  • ar500 RX - soon to be Diversity UHF
  • 1.28GHz tx 8 channel
  • FPV board cam
  • MinimOSD
  • LX0 sonar
  • 5100 LiPo
  • Total Weight ~4lbs w LiPo
  • Estimated Payload 2lbs -  not yet tested but seems reasonable w 2836/9 thrust stats

Ill amend that with RC Timer 18/20A ESCs flashed with TGY.hex with, according to the ultra helpful chart link, an internal oscillator. The original question stands, though, as to what, in fact can cause de-calibration. I should elaborate i suppose by adding that on some ESCs, the zero point ended, up starting at approx. 1200 pwm, where others would range 0 at 1040 ( real zero on my zer0-trim/centered tx) to ~ 1120 or so. In short, i can see where temperature could cause a minor to moderate( ~0-10%) decal, but that scale is SERIOUSLY larger than mushyness etc and solidly into unflyabilityville. Do you mean that temp delta can decalibrate it that seriously? Or do I need to look another direction in terms of the rest of the circuitry? Ive just gotta nail down what to avoid or do in order to prevent this in the future.

Maybe I just need to invest in a better ESC? It seems like the Silabs cant be flashed with new firmware though. Are these the ESCs that utilize an external oscillator?

THanks for the insight



I personally couldn't calibrate internally oscillated ESCs properly; they would drift after some time (mostly tested on HK-SS20A-HW which run the same tgy.hex as yours). I had to re-calibrate before every flight, doing so out in the cold helped somewhat but still rather annoying.

I've been having good success with F30A (HK 'ubec' series) lately, they're still Atmel-based so you get SimonK perks but they have external oscillator. Haven't recalibrated for months now :)

Wow- ok good info there. Sorry for the stupid questions but it seems as if eveyone else is having an easier time with everything than i am right now. It's a relief to see that others have had the same issues though.  Just to be sure i have the right one, Ive included a pic, can you verify that's the ESC youve had luck with?  

they are a reasonable price, thats for sure, Hopefully I can get HK to ship before 2014 rolls around :-)

Awesome- Thanks Dimitri & RD

Yeap, that's the one. Besides externally oscillated, it's also N-FET instead of P/N-FET which is usually more efficient especially at partial loads (most of the time in multicopters). And has programming pads for easy flashing.

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