Need assistance with servo motor potentiometer setup

Mbed OS
,
1

This code was supposed to move the servo motor when as the potentiometer turned, but for some reason, it doesn’t budge an inch. I am not sure if it is the program, the board, or my wiring. The board is a Nucleo STM L476RG board, and the servo is an SG90 micro servo motor and I was utilizing an imported copy of Jasper Denkers Servo library. If anyone could provide assistance that would be great.

#include "mbed.h"
#include "Servo.h"
#include "iostream"

Servo myservo(D6);
AnalogIn MyPot(A1);


int main() {
    float PotReading;
    PotReading = MyPot.read();

    while(1) {
     for(int i=0; i<100; i++) {
            myservo.SetPosition(PotReading);
            wait(0.01);
        }

        }
    }
2

Hi Jay,

Your code not working because:

  • you set the variable only once before the loop. The pot.read() must must be inside the loop or in a ticker if you want to change the value/PWM via the pot.
  • Also you miss information from the library. You need to read the Servo.h file where you can see on lines 30-50 an basic example how use this library. Or found a correct example of that library ServoTest. Or check the methods of that library, where you can found

Enable the servo. Without enabling the servo won’t be running.

  • Also you use a for cycle but not change the PotReading variable so you only 100 times set same value.

Edit:
Here you have a very basic example, what work with my servo, although it is not so smooth.

#include "mbed.h" //MbedOs 2
#include "Servo.h"

Servo servo(D10);
AnalogIn pot(D6);

int main() {
    servo.Enable(200,20000); // 200us start, period of 20ms in us
    while(1) {
        int value = 200+(pot.read()*2100);
        wait_ms(15);
        servo.SetPosition(value);
    }
}

BR, Jan