servo settings

Tinchus

Hello. Im having a small issue with servo. I tried different models so now I can say it is something related to the electronics and not the servosd. All servos I have tried mode well, power to the servos are provided by an independant source (6C, 2 amps, more than enough for these servos). Signal is controlled of course by a duet 3 board.
The "problem" i have is that despite the servos move very well, once final position has been reached, that position is not hold orpoerly, like if the servo looses its toorque force.

Servo on duet3 is configured with:
M950 S0 C"0.out9"

I have contacted tech support and thehy asked me the following:

What signal voltage and update rate are you using to control the servo?

I dont know that information, can oyu provide me with it?
Thanks in advance

dc42

@Tinchus which Duet are you using, and how have you connected the servo to it?

droftarts

@Tinchus Send M950 S0 to see the parameters set, eg when I set it on my Mini 5+ (using out6):

M950 S0 C"out6"
M950 S0
GPIO/servo port 0 pin (out6,laser,vfd) frequency 50Hz

Update rate is 50Hz.
Signal voltage is 3.3V if you use the out9 header (on 6HC) or 5V if you use the LASER/VFD header, which is shared with out9.

If you share a link to the servo specification, we can suggest different values for frequency, if needed.

Ian

Tinchus

@dc42 It is a duet3 board. Now it is connected to the servo/laser pin for the signal. Power for the servo is provided by an independant PSU (it is a 6V servo, signal requires 3.3V)

So following the information provided below, I have the source of my problem here. Im giving a 5V siignal to the servo instead of 3.3V

So I should change the siognal pin connection to the out9 pin the one marked as "pwm fan"?

Thanlks in advance for the help

T3P3Tony

@Tinchus if you want ot use 3.3V signalling for a hobby servo, then use any of the 6HC IO outputs that support PWM

https://docs.duet3d.com/Duet3D_hardware/Duet_3_family/Duet_3_Mainboard_6HC_Hardware_Overview#io-headers

so IO 4,5,7

those a 3.3V signalling level.

Tinchus

@T3P3Tony Thanks for the info. I will try using those ones. I have tried using out9, but using that output just doesnt work (my initial setup was connecting to tthe signal provided by the laser/servo output wich is shared with out9 right? so following advice (above) I change the conection to the out9 pin, and the servo just doesnt work.
So to have it really clear: I will connect the signal cable to the ouput pin on io4 for example?

T3P3Tony

@Tinchus said in servo settings:

So to have it really clear: I will connect the signal cable to the ouput pin on io4 for example?

yes

dc42

@Tinchus you will also need to common the grounds of your external PSU and the Duet.

Tinchus

@dc42 Thanks for the advice! Without being an electronic guy and since Y dont want to blow anything jajajaja.... can you tell me how to do this? For you to have full info: I have a PSY feeding the duet, and I have a small stepdown PSU for the servo to feed it with 6V. This stepdown get the energy from the PSU feeding the duet

jay_s_uk

@Tinchus if the stepdown is fed from the PSU feeding the Duet then you don't need to do anything