Basic understanding of ESC

I'm trying to find out what is the maximum update rate for a typical ESC is. I saw that most quad copter designed require the ESC update rate to be very high, i.e 100Hz or more.My understanding a ESC takes a PPM signal from 1ms to 2ms with a 20ms duty cycle. So a max of 50Hz update rate, is that correct? Is there some "play" in the duty cycle maybe max of 10ms. Or I'm way off base? Looking at ESC data sheets seem to be missing this information.
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  • thank you, a lot of good stuff here...
  • It's all there, look at the schematics in the hardware folder
  • I saw your web page for your quad, could you share a parts list?
  • Yes, you can set the minimum and maximum throttle with the programming card or with the interactive setup, I don't remember the procedure since I did it long ago.
  • Hm, ok, impressive. Guess I just assumed they werent that sensitive. When you say "set up" you mean with one of those ESC programmer cards?
  • I wrote "alomost 500 Hz" and I meant exactly that, it's actually around 490 Hz. I use pulse widths of 0.8 to 1.8 msec (I set up the ESC for that).

    Dror
  • Yes, this a quad. I'm waiting on new micro controller LPC2148 board... for a first pass, then a PIC32, a new version is coming from sparkfun with 512K flash and 128k of RAM...
  • It's hard to say. Not an easy thing to test. Probably depends on the motor (torque and mass), as well as what it's attached to. Anecdotally, seems like 100hz helps with a quad. More than that is debatable. Some people do claim they get a lot more out of their fancy 1khz escs. For me, not worth the extra money, at least for now. You can certainly get a flying quad with 100hz, probably even 50hz.

    If we're talking about anything other than a quad, you probably dont need anywhere near this level of control.
  • Even if you change the ESC at 100Hz can the motor see that change that quickly?
  • At 500Hz 2ms pulses will blend into a steady signal. Never tried it, but it seems like that would confuse the esc.
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