Servo motors are not disabling/releasing after setting angle to None

[scprotz]

I'm using a Raspberry Pi 4 to control the PCA9685. I have generic MG996R-style servos connected (2 different brands). When I set the servo.angle = None, the servos just hold their current position without releasing.

I'm using servokit 1.3.13, pca9685 3.4.6, and motor 3.4.5

(I do have a version on a different raspberry pi that is running servokit 1.3.6, pca9685 3.39 and motor 3.3.2 that does work correctly, though it uses a different brand of servo).

I am not quite sure if this is due to a regression or certain brands of servos not recognizing the angle = None.

Any insight would be appreciated. I may try to upgrade the second raspberry pi and see if those servos get the issue. That would help narrow down if this is a per-servo-brand bug or a regression.

[Recelis]

I have the same issue too. My micro servo motors are disabling correctly but it seems like the bigger servos 1501MG https://www.pololu.com/product/1057 aren't being disabled.

[ladyada]

do you know that the motors will 'release' when not receiving a 50hz signal because thats the only way to release motors - if your servo doesnt do that, it has nothing to do with this firmware

[scprotz]

How can we programmatically tell it not to send the 50hz signal then. I would have thought setting angle = None should do something like that. Is there another command?

[scprotz]

So just a note. It appears I can set the duty_cycle to nothing and it turns off this type of servo.

There are two ways (which are effectively the same based on the source code in github):

either kit.servo[0]._pwm_out.duty_cycle = 0

or kit.servo[0].fraction = None

Both of these turn off duty cycle 'release' the motor.

[scprotz]

I misspoke. This does not release the motor. It just stops the duty cycle. I'll play around and see if there is another way to cut power completely to the servo.

[arnaudbore]

@scprotz do you have any update on this? It feels like you've been working with this for quite some time. If you have some time can you answer #73 ? Thank you in advance

[scprotz]

Just wanted to add another comment. I have tried a number of things and still certain brands of motors will not disconnect/release when I set fraction = None, nor Angle = None. It appears there is a way to turn off the servo pins on the PCA9685. On this page: https://learn.adafruit.com/16-channel-pwm-servo-driver/library-reference It states that (using an Arduino), I can setPWM(1, 0, 4096) to disable the servo pins (and I hope turn off the servo).

Is there a way to do the same with CircuitPython_Motor (or one of the lower level APIs)?

[scprotz]

Extra notes: https://forums.adafruit.com/viewtopic.php?f=22&t=178641 says that setting the PWM duty_cycle to 0 should shut off the PCA9685 pins, but again, this does not seem to be the case as some servos continue to 'hold' even after setting the duty cycle to 0 for those servo's pins.