Electric Stunt > ESC Settings

question PWM or Blheli or?

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dave siegler:
So I have a timer design that i have been using, it works great.  It has a MEMS accelerometer so can trim up the power for climbs and turns. 

Mine uses the simple servo pulses from the timer to the ESC. 

Does anyone use the higher speed protocols that the ESC can use directly like Blheli to get faster responses?

The drone guys get higher performance out of the motor cooler operation and quieter operation,  I know its not the same application. 

So does a faster timer to ESC protocol help?     

CircuitFlyer:
I can't see how it would make a noticeable difference.  Relatively speaking, things just don't happen that fast in control line.  A typical PWM signal updates every .02 seconds.  For a typical stunter that equates to about 16 inches of linear travel and approximately 3 rotations of the prop.  How much change in velocity happens over that 16 inches?  Is it enough to warrant faster updates?  Oneshot125 can update 8 times faster, approximately every 2 inches along the flight path and 1/3 of a rotation of the prop (maybe 5 pulses from the RPM sensor).  What is the loop time on your PID controller?  How accurate is the RPM calculations based on fewer pulses?  A lot of things to consider.

I think you would see a much larger gain in performance just by using ESC's that have very little to no input filtering before going to a faster protocol.

dave siegler:
most likely you are right.  But I wonder if people get access to other times in the esc's data table.  The data that shows up on drone flight controller is impressive

Dennis Toth:
CF,
Are you using 8 as the PWM in the ESC for your .02 sec? The BadAss motors use 8 as the standard starting point. I guess another option in to increase that to 12, but this will increase temps in the ESC and motor some need to make sure the cooling is very good.

Best,    DennisT

CircuitFlyer:
Dennis,

Dave was referring to the PWM rate of the throttle signal used for the ESC input.  Control line timers currently use 50Hz, 50 times a second or one pulse every .02 seconds. 

I think you are referring to the PWM rate used to chop up the motor voltage signal on the ESC output.  8k, 12k or 16kHz.  Yes, I agree, it can be confusing.

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