Servo SAADC With nRF52832

[L.Baggio]

Hello everybody. I need to rotate servo and check adc on potentiometer to stop it if something is blocking the shaft.

I need to change servo position step by step and check saadc values on each step.

I was able to measure voltage on potentiometer using saadc library and rotate servo with PWM Library in one project, everything works fine, but don't know how to check voltage on every step.

I am very new to microcontroller development and particularly to nrf. On Arduino changing steps just in for loop and measuring voltage gave me that I want. but in nrf52832 I can't find something like that.

I hope for your help. Thank you..

[haakonsh]

but don't know how to check voltage on every step.

 What do you mean by every step? 

Can you share your code?

[L.Baggio]

I mean how can I check if something is blocking the shaft of servo while rotating?

[haakonsh]

That depends on your application.  

The most omportant question is exactly WHEN do you want to sample the ADC? 

What control signals do you send to the servo? 

Is the servo just a DC motor, AC motor, stepper motor, or a regular hobby servo?

[L.Baggio]

hi

I'am using MG996R, hobby servo 0-180 degrees.

I'm sending signal using pwm driver library with this function: nrfx_pwm_simple_playback(&m_pwm0, &seq0, 1, NRFX_PWM_FLAG_STOP);

I want to sample the adc while sending commands to servo or is there other method to check if shaft is blocked?

[haakonsh]

I suggest you use the Limits event monitoring feature of the SAADC. This feature enables the SAADC to function similarly to a comparator. 

You can set up the limits to correspond with a servo blocking state and start and stop continuous sampling on the PWM's EVENTS_SEQSTARTED and EVENTS_SEQEND events respectivly. 
Then the SAADC will operate only when the PWM is running, and notify your application when the prest voltage limit has been reached.