Example Code for Arduino-PWM mode drive DC motor with encoder

Hardware Preparation

• DFR0994 Romeo ESP32-S3 x 1
• TT Motor with Encoder x1

Software Preparation

• Download Arduino IDE: Click to download Arduino IDE
• Add ESP32 board to Arduino IDE

PWM mode drives the motor

Truth table of PWM control mode

Sample Code

The motor rotation speed is controlled by PID

/**
 *@brief motorSpeeddetectionbyPWMwithencoder.ino
 *@ Motor driver in PWM mode (with encoder)
 */
#include "driver/mcpwm.h"
#include "soc/mcpwm_struct.h" 
#include "soc/mcpwm_reg.h"
#include <PID_v1.h>

//IO12->M1_IN1
//IO13->M1_IN2
#define MOTOR_PWM_IN1 12 
#define MOTOR_PWM_IN2 13

const byte encoder0pinA = 3;//A pin -> the interrupt pin 3
const byte encoder0pinB = 4;//B pin -> the digital pin 4
byte encoder0PinALast;
double duration,abs_duration;//the number of the pulses
boolean Direction;//the rotation direction
boolean result;
double val_output;//Used to provide PWM power values to the motor.
double Setpoint;
double Kp=0.6, Ki=5, Kd=0;
PID myPID(&abs_duration, &val_output, &Setpoint, Kp, Ki, Kd, DIRECT);

//Initialize the pins needed to generate the PWM signal
void mcpwm_init(void)
{
  //The binding needs to output the PWM pin to the PWM channel
  mcpwm_gpio_init(MCPWM_UNIT_0,MCPWM0A,MOTOR_PWM_IN1);
  mcpwm_gpio_init(MCPWM_UNIT_0,MCPWM0B,MOTOR_PWM_IN2);

  //Configure mcpwm information
  mcpwm_config_t pwm_config;
  pwm_config.frequency = 1000;/*!<Set frequency of MCPWM in Hz*/
  pwm_config.cmpr_a = 0;/*!<Set % duty cycle for operator a(MCPWMXA), i.e for 62.3% duty cycle, duty_a = 62.3*/
  pwm_config.cmpr_b = 0;/*!<Set % duty cycle for operator b(MCPWMXB), i.e for 48% duty cycle, duty_b = 48.0*/
  pwm_config.counter_mode/*!<Set  type of MCPWM counter*/ = MCPWM_UP_COUNTER/*!<For asymmetric MCPWM*/; 
  pwm_config.duty_mode/*!<Set type of duty cycle*/ = MCPWM_DUTY_MODE_0/*!<Active high duty, i.e. duty cycle proportional to high time for asymmetric MCPWM*/;

  // Initializes a unit of mcpwm and binds the clock
  mcpwm_init(MCPWM_UNIT_0,MCPWM_TIMER_0,&pwm_config);
}


void advance(/*range：0~100*/uint8_t speed)
{
  mcpwm_set_duty_type(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_A,MCPWM_DUTY_MODE_0);
  mcpwm_set_signal_low(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_B);
  mcpwm_set_duty(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_A,speed);
}

void retreat(/*range：0~100*/uint8_t speed)
{
  //Give MOTOR_DIRECTION_PIN a continuous low level
  mcpwm_set_signal_low(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_A);

  /*
   * Call function mcpwm_set_duty_type() every time after mcpwm_set_signal_high() 
   * or mcpwm_set_signal_low() to resume with previously set duty cycle.
   */
  mcpwm_set_duty_type(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_B,MCPWM_DUTY_MODE_0);
  
  //The MOTOR_STEP_PIN pin outputs a PWM wave with a duty cycle of "speed"
  mcpwm_set_duty(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_B,speed);
}

void stop(void)
{
  mcpwm_set_signal_low(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_A);
  mcpwm_set_signal_low(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_B);
}

void breake(void)
{
  mcpwm_set_signal_high(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_A);
  mcpwm_set_signal_high(MCPWM_UNIT_0,MCPWM_TIMER_0,MCPWM_GEN_B);
}

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 EncoderInit()
{
  Direction = true;//default -> Forward
  pinMode(encoder0pinB,INPUT);
  attachInterrupt(digitalPinToInterrupt(encoder0pinA), wheelSpeed, CHANGE);
}

void setup() {
  Serial.begin(115200);//Initialize the serial port
  mcpwm_init();
  advance(70);
  Setpoint =80;  //Set the output value of PID
  myPID.SetMode(AUTOMATIC);//Set PID to automatic mode
  myPID.SetSampleTime(100);//Set the PID sampling frequency to 100ms
  EncoderInit();//Initialize the module
}

void loop() {
  abs_duration=abs(duration);
  result=myPID.Compute();//The return value of PID conversion is 1
  if(result)
  {
    Serial.print("Pluse: ");
    Serial.println(duration);
    duration = 0; //Count clear and wait for the next count
  }  
}