open_loop_youtube.ino

//Program to run a brushless motor in open loop mode
//By Juan Pablo Angulo
//Ask me questions: https://www.patreon.com/randomaccessprojects
//A simple DIY circuit to run it can be found in my Patreon: https://www.patreon.com/randomaccessprojects
//Thanks for your support!

const int potPin = A1;  // INPUT pot control for speed or position
//use ports 9, 10, 11 
const int motorPin1 =9;
const int motorPin2 =10;
const int motorPin3 =11;

// Variables
int pwmSin[] = {127,110,94,78,64,50,37,26,17,10,4,1,0,1,4,10,17,26,37,50,64,78,94,110,127,144,160,176,191,204,217,228,237,244,250,253,255,253,250,244,237,228,217,204,191,176,160,144,127}; // array of PWM duty values for 8-bit timer - sine function
int currentStepA=0; //initial pointer at 0   degrees for coil A
int currentStepB=16;//initial pointer at 120 degrees for coil B
int currentStepC=32;//initial pointer at 240 degrees for coil C
int pos;

//SETUP
void setup() {
  Serial.begin(9600);
//next commands will change the PWM frequency, so the annoying sound generated can be moved above human ear capability.
  TCCR0B = TCCR0B & 0b11111000 | 0x03 ;// changing this will also affect millis() and delay(), better to leave it default (0x03).
  TCCR1B = TCCR1B & 0b11111000 | 0x01; // set PWM frequency @ 31250 Hz for Pins 9 and 10, (0x03 is default value, gives 490 Hz).
  TCCR2B = TCCR2B & 0b11111000 | 0x01; // set PWM frequency @ 31250 Hz for Pins 11 and 3, (0x03 is default value, gives 490 Hz).
  
  ICR1 = 255 ; // 8 bit resolution for PWM
 
  pinMode(potPin, INPUT);
  pinMode(motorPin1, OUTPUT);
  pinMode(motorPin2, OUTPUT);
  pinMode(motorPin3, OUTPUT);
}
 
void loop() {
  move();
}
  
void move()
{
  currentStepA = currentStepA + 1;  //Add 1 to make the motor move step by step.
  currentStepB = currentStepA + 16; //add 120 deg of phase to whatever position StepA is. 
  currentStepC = currentStepA + 32; //add 240 deg of phase to whatever position StepA is.
  
  currentStepA = currentStepA%48; //I used remainder operation or modulo to "wrap" the values between 0 and 47
  currentStepB = currentStepB%48;
  currentStepC = currentStepC%48;

  analogWrite(motorPin1, pwmSin[currentStepA]*1); //multipliying by 0.5 to reduce output torque to half as its being supplied with 12V and can get pretty warm. make this 1 if supply is 5V or if you know what you are doing ;)
  analogWrite(motorPin2, pwmSin[currentStepC]*1);
  analogWrite(motorPin3, pwmSin[currentStepB]*1);

  //Following send data to PLX-DAQ macro for Excel
  /*Serial.print("DATA,");
  Serial.print(pwmSin[currentStepA]);
  Serial.print(","); 
  Serial.print(pwmSin[currentStepB]);
  Serial.print(","); 
  Serial.println(pwmSin[currentStepC]);
  */

  //Read pot value
  int sensorValue = analogRead(potPin); 

// Select ONLY ONE of the following lines for constant speed, speed control or position control:

  //This will give you constant speed, remember if you changed TCCR0B to 0x01, then delay(64000) = ~1 second
  //delay(5); 

  //This will give you open loop speed control with the potentiometer
  //delay(sensorValue/10);

  //This will give you open loop position control with the potentiometer
  currentStepA = sensorValue/5; //divide by a number to affect the ratio of pot position : motor position

 ////////////

   
//Serial.println(currentStepA);
  //pos=pulseIn(encoder,HIGH);
  //Serial.println(pos);
}