I’m installing a new FC in one of my TRex500 helis and, despite running three Ardupilot helis for a few years, can’t remember the detail of what I did before.
My four servos are connected to PWM outputs 2, 3, 4, and 5 and my CC Talon ESC to output 7. I am using the ESC’s governor to give a head speed of 1650rpm (4 blade head). It works, but I can’t remember the significance of the instruction “. . . see that RC3_MIN and RC3_MAX match the MIN and MAX range of the HeliRSC output, which defaults to SERVO08 output . . . “. I don’t remember having to do anything with RC3_ before.
My MAX for output 7 is set to 1500 because CC calculates that 1.486uS is the value for 1650rpm.
When you temporarily set your HeliRSC channel’s SERVOx_FUNCTION to 53 for RC3 (throttle channel) passthrough, if the RC in and the SERVOx out don’t match, you could potentially have an inaccurate calibration after you switch it back to normal configuration.
It may have been close enough in your past experiences that it didn’t matter.
Although your end result may be good on your governor speed, if it was me, I would still want to go back and do Castle Creations’ Throttle Calibration with Fixed Endpoints using MP’s Servo Output page to change low and high positions, and then setup the governor.
This method will have you start with high and low throttle values more towards each other in the middle of the range and then find the exact high and low for your ESC.
Thank you Mike. I hadn’t seen that CC leaflet before, but on reading it now I can’t understand how it relates to using the ESC in governor mode. My understanding was that once the ESC had been programmed through the CC app, the desired (programmed) rpm would be achieved whenever the PWM input was equal to or above the value given by the CC programming app. And that seems to be working for my three helis. Whenever I arm the helis the head spools up slowly until it reaches the governed speed, and then stays there whatever position the Tx collective stick is at.
I’ve just looked at the parameters for my three helis and I see that in each case RC3_MAX and _MIN are equal at 2006 and 982 (they’re all using the same Tx). My SERVOx (where x is 7 in two instances and 10 in the other) HeliRSC values are 1100/1900 or 1000/2000. So it sounds like, as you suggest, the RC3 and SERVOx values are close enough to each other.
CC’s governor setup guide states “*For this function to work properly the throttle channel of you
Tx must be calibrated in accordance to the “Setting Up Fixed
Endpoint” Instructions.”
But if you set all three “Desired Head Speeds” in CastleLink to the same RPM, practically speaking, I guess it doesn’t matter since H_RSC_SETPOINT will be somewhere within range.
Thanks Mike. Yes, I do set all three speeds to the same rpm, so that’s why it’s working for me. I’d forgotten about the option to have three different governed speeds, for which more-detailed programming would be required.