Servo with Firmware 3.3

Marco_76

Hi, I just updated my firmware from 2.05 to the latest version 3.3
I have a duet wifi + duex configuration and I'm now doing all required changes.

I'm using a servo which was working fine with the old configuration. It is attached to the duex PWM pins. Here changes I did:

OLD Config.g
M307 H5 A-1 C-1 D-1 ; Disable the 5th Heater to free up PWM channel 3 on the Duex board
NEW Config.g
M950 P0 C"exp.heater5" ; map 5th Heater or PWM channel 3 on the Duex board

with the old configuration, to move the servo from 0 to 180 degrees I was just using M280 P0 S0, or M280 P0 S90. Now it is still moving, but the servo doing very small movements (about 10 degrees).

My servo is an MG996R

Thanks for your help.

Marco

dc42

@marco_76 said in Servo with Firmware 3.3:

M950 P0 C"exp.heater5" ; map 5th Heater or PWM channel 3 on the Duex board

For servos, use S0 in that command not P0.

Marco_76

@dc42 I tired but using S0 it is not even moving. At least with P0 was doing small angle movements. any Idea?

dc42

@marco_76 P0 uses the wrong PWM frequency which is why the movements were incorrect. S0 defaults to a lower frequency, 50HZ AFAIR. Try S0 again. If that doesn't work, try P0 Q50.

Marco_76

@dc42
I confirm that if I use M950 S0 C"exp.heater5" doesn't work. I tired with M950 S0 C"exp.heater5" Q500 and it's working but with the small movement again. I checked the tech specs of the servo and should operate at 50Hz.

dc42

@marco_76 I said use Q50 not Q500. Did you try that?

Edit: you may need to invert the pin i.e. use "!exp.heater5", I can't remember.

Marco_76

@dc42 Thank you. The issue was in the pin to be inverted. I used "!exp.heater5" and not it's working again.

As always you are top starts in supporting the community.