Example Code for Arduino-Motor Speed PID Control

Hardware Preparation

• DFRduino UNO x1
• DC power supply x1
• L298 x1

Software Preparation

• Arduino IDE Download Arduino IDE
• Download and install Arduino PID

Wiring Diagram

This tutorial is intended to use the encoder, Select D2 pin and D3 pin, Wherein D2 as an interrupt port, D3 as an input pin. In practice, two pins need to ensure that one of pins must be an interrupt pin, and the other definable (see the interrupt port with different board).

Other Preparation Work

1. Motor power port is connected to the L298 drive motor M1 port
2. Download and install Arduino PID

Sample Code

//The sample code for driving one way motor encoder
#include <PID_v1.h>
const byte encoder0pinA = 2;//A pin -> the interrupt pin 0
const byte encoder0pinB = 3;//B pin -> the digital pin 3
int E_left =5; //The enabling of L298PDC motor driver board connection to the digital interface port 5
int M_left =4; //The enabling of L298PDC motor driver board connection to the digital interface port 4
byte encoder0PinALast;
double duration,abs_duration;//the number of the pulses
boolean Direction;//the rotation direction
boolean result;

double val_output;//Power supplied to the motor PWM value.
double Setpoint;
double Kp=0.6, Ki=5, Kd=0;
PID myPID(&abs_duration, &val_output, &Setpoint, Kp, Ki, Kd, DIRECT);

void setup()
{
  Serial.begin(9600);//Initialize the serial port
   pinMode(M_left, OUTPUT);   //L298P Control port settings DC motor driver board for the output mode
   pinMode(E_left, OUTPUT);
   Setpoint =80;  //Set the output value of the PID
   myPID.SetMode(AUTOMATIC);//PID is set to automatic mode
   myPID.SetSampleTime(100);//Set PID sampling frequency is 100ms
  EncoderInit();//Initialize the module
}

void loop()
{
      advance();//Motor Forward
      abs_duration=abs(duration);
      result=myPID.Compute();//PID conversion is complete and returns 1
      if(result)
      {
        Serial.print("Pluse: ");
        Serial.println(duration);
        duration = 0; //Count clear, wait for the next count
      }


}

void EncoderInit()
{
  Direction = true;//default -> Forward
  pinMode(encoder0pinB,INPUT);
  attachInterrupt(0, wheelSpeed, CHANGE);
}

void wheelSpeed()
{
  int Lstate = digitalRead(encoder0pinA);
  if((encoder0PinALast == LOW) && Lstate==HIGH)
  {
    int val = digitalRead(encoder0pinB);
    if(val == LOW && Direction)
    {
      Direction = false; //Reverse
    }
    else if(val == HIGH && !Direction)
    {
      Direction = true;  //Forward
    }
  }
  encoder0PinALast = Lstate;

  if(!Direction)  duration++;
  else  duration--;

}
void advance()//Motor Forward
{
     digitalWrite(M_left,LOW);
     analogWrite(E_left,val_output);
}
void back()//Motor reverse
{
     digitalWrite(M_left,HIGH);
     analogWrite(E_left,val_output);
}

void Stop()//Motor stops
{
     digitalWrite(E_left, LOW);
}

Result

The code PID value has been set as 80, so the motor will stabilize at about 80 rpm. If outside forces such as changes in motor drive voltage, the motor's resistance, etc affect the speed, the program will adjust the PWM value to stabilize the rotational speed at 80.