Atmega328p -- > esp32 program migration

Other Hardware Motors, Mechanics, Power and CNC
1

Hey, guys,
Now I'm working on a motor speed regulation project. I saw a program based on atmega328p Au processor. There's no problem with Arduino compilation, but now I want to use esp32 development board to replace atmega328p Au. There are errors in the compilation of timer. Please tell me how to modify it?

Original author project link

source program ↓

String mySt = "";
char myChar;
boolean stringComplete = false;  // whether the string is complete
boolean motor_start = false;
const byte pin_a = 2;   //for encoder pulse A
const byte pin_b = 3;   //for encoder pulse B
const byte pin_fwd = 4; //for H-bridge: run motor forward
const byte pin_bwd = 5; //for H-bridge: run motor backward
const byte pin_pwm = 6; //for H-bridge: motor speed
int encoder = 0;
int m_direction = 0;
int sv_speed = 100;     //this value is 0~255
double pv_speed = 0;
double set_speed = 0;
double e_speed = 0; //error of speed = set_speed - pv_speed
double e_speed_pre = 0;  //last error of speed
double e_speed_sum = 0;  //sum error of speed
double pwm_pulse = 0;     //this value is 0~255
double kp = 0;
double ki = 0;
double kd = 0;
int timer1_counter; //for timer
int i = 0;

void setup() {
  pinMode(pin_a, INPUT_PULLUP);
  pinMode(pin_b, INPUT_PULLUP);
  pinMode(pin_fwd, OUTPUT);
  pinMode(pin_bwd, OUTPUT);
  pinMode(pin_pwm, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(pin_a), detect_a, RISING);
  // start serial port at 9600 bps:
  Serial.begin(9600);
  
  //--------------------------timer setup
  noInterrupts();           // disable all interrupts
  TCCR1A = 0;
  TCCR1B = 0;
  timer1_counter = 59286;   // preload timer 65536-16MHz/256/2Hz (34286 for 0.5sec) (59286 for 0.1sec)


  TCNT1 = timer1_counter;   // preload timer
  TCCR1B |= (1 << CS12);    // 256 prescaler
  TIMSK1 |= (1 << TOIE1);   // enable timer overflow interrupt
  interrupts();             // enable all interrupts
  //--------------------------timer setup

  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  analogWrite(pin_pwm, 0);  //stop motor
  digitalWrite(pin_fwd, 0); //stop motor
  digitalWrite(pin_bwd, 0); //stop motor
}

void loop() {
  if (stringComplete) {
    // clear the string when COM receiving is completed
    mySt = "";  //note: in code below, mySt will not become blank, mySt is blank until '\n' is received
    stringComplete = false;
  }

  //receive command from Visual Studio
  if (mySt.substring(0, 8) == "vs_start") {
    digitalWrite(pin_fwd, 1);     //run motor run forward
    digitalWrite(pin_bwd, 0);
    motor_start = true;
  }
  if (mySt.substring(0, 7) == "vs_stop") {
    digitalWrite(pin_fwd, 0);
    digitalWrite(pin_bwd, 0);     //stop motor
    motor_start = false;
  }
  if (mySt.substring(0, 12) == "vs_set_speed") {
    set_speed = mySt.substring(12, mySt.length()).toFloat(); //get string after set_speed
  }
  if (mySt.substring(0, 5) == "vs_kp") {
    kp = mySt.substring(5, mySt.length()).toFloat(); //get string after vs_kp
  }
  if (mySt.substring(0, 5) == "vs_ki") {
    ki = mySt.substring(5, mySt.length()).toFloat(); //get string after vs_ki
  }
  if (mySt.substring(0, 5) == "vs_kd") {
    kd = mySt.substring(5, mySt.length()).toFloat(); //get string after vs_kd
  }
}

void detect_a() {
  encoder += 1; //increasing encoder at new pulse
  m_direction = digitalRead(pin_b); //read direction of motor
}
ISR(TIMER1_OVF_vect)        // interrupt service routine - tick every 0.1sec
{
  TCNT1 = timer1_counter;   // set timer
  pv_speed = 600.0 * (encoder / 130.0) / 0.1; //calculate motor speed, unit is rpm
  encoder = 0;
  //print out speed
  if (Serial.available() <= 0)
  {
    Serial.println(pv_speed);         //Print speed (rpm) value to Visual Studio
  }

  //PID program
  if (motor_start) {
    e_speed = set_speed - pv_speed;
    pwm_pulse = e_speed * kp + e_speed_sum * ki + (e_speed - e_speed_pre) * kd;
    e_speed_pre = e_speed;  //save last (previous) error
    e_speed_sum += e_speed; //sum of error
    if (e_speed_sum > 1320) e_speed_sum = 1320;
    if (e_speed_sum < -1320) e_speed_sum = -1320;
  }
  else {
    e_speed = 0;
    e_speed_pre = 0;
    e_speed_sum = 0;
    pwm_pulse = 0;
  }
  
  //update new speed
  if (pwm_pulse <255 & pwm_pulse >0) {
    analogWrite(pin_pwm, pwm_pulse); //set motor speed
  }
  else {
    if (pwm_pulse > 255) {
      analogWrite(pin_pwm, 255);
    }
    else {
      analogWrite(pin_pwm, 0);
    }
  }
}
void serialEvent() {
  while (Serial.available()) {
    // get the new byte:
    char inChar = (char)Serial.read();
    // add it to the inputString:
    if (inChar != '\n') {
      mySt += inChar;
    }
    if (inChar == '\n') {
      stringComplete = true;
    }
  }
}

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image1457×481 27.5 KB

Migrating Atmega2560 to ESP32
2

The ESP32 does not use Uno code.

The ESP32 has 4 hardware timers, General Purpose Timer - ESP32 - — ESP-IDF Programming Guide v4.3.2 documentation.

void IRAM_ATTR onTimer()
{
  BaseType_t xHigherPriorityTaskWoken;
  xEventGroupSetBitsFromISR(eg, OneMinuteGroup, &xHigherPriorityTaskWoken);
} // void IRAM_ATTR onTimer()
////

void setup()
{
  // hardware timer 4 set for one minute alarm
  timer = timerBegin( 3, 80, true );
  timerAttachInterrupt( timer, &onTimer, true );
  timerAlarmWrite(timer, 60000000, true);
  timerAlarmEnable(timer);
}
3

If you do not want to get into the details of the timers on the ESP32 I would recommend using Ticker.h which is a hardware timer library bundled into the Arduino Core for the ESP32.

There are library examples which will show you how to implement a repeating interval with a function call.

4

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