Example Code for Arduino-Servo Control with Analog Feedback

Hardware Preparation

• DFRduino UNO R3 (or similar) x 1
• SER0044 DSS-M15S 270° Metal Servo
• M-M/F-M/F-F Jumper wires

Software Preparation

• Arduino IDE, Click to Download Arduino IDE from Arduino®

Wiring Diagram

Other Preparation Work

Before Usage
There will be some error between each servos. If you want to use the servos with scenes that require precise control, you can calibrate them separately. A quick three-point calibration method is provided here:

• 1. Drive the servo to 90 degrees (1500us), record the actual angle as reference angle A, and record the corresponding feedback analog value a;
• 2. Drive the servo to 0 degrees (500us), record the actual angle as reference angle B, and record the corresponding feedback analog value B:
• 3. Drive the servo to 270 degrees (2500c), record the actual angle as reference angle C, and record the corresponding feedback analog value C

The following formula gives the relationship between Analog value & Angle:

• Actual angle = m * Analog value n
• m=[(A-B)/(a-b) (C-A)/(c-a)]/2
• n=[(Ab-Ba)/(b-a) (Bc-Cb)/(c-b)]/2

If you doesn't need such accurate value, you can use m=0.47;n=-33.4 directly.

Sample Code

#include <Servo.h>

Servo myservo;  // create servo object to control a servo


void setup() {
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
}

void loop() {
  int pos = 0;  // variable to store the servo position
  uint16_t val;
  double dat;

  for (pos = 0; pos <= 180; pos += 1) {  // goes from 0 degrees to 180 degrees
    myservo.write(pos);                  // tell servo to go to position in variable 'pos'
    delay(15);
    val = analogRead(A0);  //Connect Analog pin to A0
    dat = (double)val * 0.47 - 33.4;
    Serial.print("Position:");  //Display the position on Serial monitor
    Serial.print(dat);
    Serial.println("Degree");  // waits 15ms for the servo to reach the position
  }

  for (pos = 180; pos >= 0; pos -= 1) {  // goes from 180 degrees to 0 degrees
    myservo.write(pos);                  // tell servo to go to position in variable 'pos'
    delay(15);
    val = analogRead(A0);  //Connect Analog pin to A0
    dat = (double)val * 0.47 - 33.4;
    Serial.print("Position:");  //Display the position on Serial monitor
    Serial.print(dat);
    Serial.println("Degree");  // waits 15ms for the servo to reach the position
  }
}

Result

Arduino will drive the servo with D9 pin, and receive the Analog feedback from A0 port.