Phase correct PWM : Inverting Mode ERROR for use in sine 3 phase pwm

wongsagornkunlaphaet · November 26, 2023, 6:41am

I am trying to create a 3 phase sine PWM signal from all 6 pins using the code from https://github.com/cmasenas/3-Phase-Sine-Arduino/blob/Release/DDS_Generator.ino Modified to be 6 pins (with low side) which can be used OCR1A (High A) and OCR1B (Low A or Inverting Mode of OCR1A), OCR4A (High B) and OCR4B (Low B), OCR3A (High C) and OCR3B (Low C). After trying to simulate in the program, it was found that phase A has no problem, phase C has no problem. But phase B (OCR4B cannot be invert of OCR4A) has a problem. Please help me view and edit the code.Use code tags to format code for the forum

#include "avr/pgmspace.h" 
/*#define Nsample 256
#define Nsample_2_3 175
#define Nsample_1_3 85*/
//#include "PWM2560EBIKE.h"

// Look Up table of a single sine period divied up into 256 values. 
const PROGMEM int sine256[]  = {
  127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
  242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
  221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
  76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
  33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124
};

/*int Isample_a =0; int Isample_b =0; int Isample_c =0;
int Xsample_a =0; int Xsample_b =0; int Xsample_c =0;
int Vm = 1023;
int Vx = 1023;
int fm = 0;
int Vmid = (ICR1+1)>>1;
int duty = 100;*/

#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit)) //define a bit to have the properties of a clear bit operator
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit)) //define a bit to have the properties of a set bit operator

int deadtime = 2;

//High side
int PWM1 = 11;// PWM1 output, phase 1 OC1A
int PWM2 = 6; //PWM2 ouput, phase 2 OC4B        
int PWM3 = 5; //PWM3 output, phase 3 OC3A
//Low side
int PWM4 = 12; //PWM4 output, phase 1 OC1B
int PWM5 = 7; //PWM5 output, phase 2 OC4C
int PWM6 = 2; //PWM5 output, phase 3 OC3B

int phaseshift_1 = 85; //offset 1 is 120 degrees out of phase 256/3 = 85
int phaseshift_2 = 170; //offset 2 is 120 degrees out of phase 256*2/3 = 170

double dfreq;
const double refclk=31376.6;      // measured output switching frequency

// variables used inside interrupt service declared as voilatile
volatile byte current_count;              // Keep track of where the current count is in sine 256 array
volatile byte ms4_delay;             //variable used to generate a 4ms delay
volatile byte c4ms;              // after every 4ms this variable is incremented, its used to create a delay of 1 second
volatile unsigned long phase_accumulator;   
volatile unsigned long tword_m;  // dds tuning word m
// Hall sensor 
/*int HallY = A1;
int HallG = A2;
int HallB = A3;*/

void setup()
{
  pinMode(PWM1, OUTPUT);      //sets the digital pin 11 as output
  pinMode(PWM2, OUTPUT);      //sets the digital pin 6 as output
  pinMode(PWM3, OUTPUT);      //sets the digital pin 5 as output
  pinMode(PWM4, OUTPUT);      //sets the digital pin 12 as output
  pinMode(PWM5, OUTPUT);      //sets the digital pin 7 as output
  pinMode(PWM6, OUTPUT);      //sets the digital pin 2 as output
  
  Setup_timer1();
  Setup_timer4();
  Setup_timer3();
  
  //Disable Timer 0 interrupt to avoid any timing delays
  cbi (TIMSK0,TOIE0);              //disable Timer0 delay() is now not available
  sbi (TIMSK1,TOIE1);              //enable Timer2 Interrupt

  dfreq=50.0;                    //initial output frequency = 50.0 Hz
  tword_m=pow(2,32)*dfreq/refclk;  //calulate DDS new tuning word 

}
void loop()
{
  while(1) 
  {
      if (c4ms > 250) // c4ms = 4ms, thus 4ms *250 = 1 second delay
       {                 
        c4ms=0;                          //Reset c4ms
        dfreq=analogRead(0);             //Read voltage on analog 0 to see desired output frequency, 0V = 0Hz, 5V = 1.023kHz
        cbi (TIMSK1,TOIE1);              //Disable Timer2 Interrupt
        tword_m=pow(2,32)*dfreq/refclk;  //Calulate DDS new tuning word
        sbi (TIMSK1,TOIE1);              //Enable Timer2 Interrupt 
       
      }
  }
}

void Setup_timer1(void)
{
  // Timer1 Clock Prescaler to : 1
  // Set clock prescale to 1 for maximum PWM frequency
  // TCCR1B |= (0 << CS12) | (0 << CS11) | (1 << CS10); //
  sbi (TCCR1B, CS10);
  cbi (TCCR1B, CS11);
  cbi (TCCR1B, CS12);

  // Timer1 PWM Mode set to Phase Correct PWM มันตั้งได้ 2 Register คือ A กับ B โดยจะตั้ง A เป็น High (Non-invert), B เป็น Low (Invert)
  //      MODE              COMnX1  COMnX2                        DesCription
  // Fast PWM                  1       0        Clear OCnX on compare, Set OCnX at BOTTOM (non-inverting)
  // Fast PWM                  1       1        Set OCnX on compare, Clear OCnX at BOTTOM (inverting)
  // PWM Phase/Freq Correct    1       0        Clear OCnX on compare Up-Cnt, Set OCnX on compare Down-Cnt
  // PWM Phase/Freq Correct    1       1        Set OCnX on compare Up-Cnt, Clear OCnX on compare Down-Cnt  

  // TCCR1A |= (1 << COM1A1) | (0 << COM1A0); //non-inverting 
  cbi (TCCR1A, COM1A0);      
  sbi (TCCR1A, COM1A1);

  // TCCR1A |= (1 << COM1B1) | (1 << COM1B0); //inverting
  sbi (TCCR1A, COM1B0); 
  sbi (TCCR1A, COM1B1);

  // Mode 1 / Phase Correct PWM
  sbi (TCCR1A, WGM10); 
  cbi (TCCR1A, WGM11);
  cbi (TCCR1B, WGM12);
  cbi (TCCR1B, WGM13);
}

//Timer 1 setup 
//Set prscaler to 1, PWM mode to phase correct PWM,  16000000/510 = 31372.55 Hz clock
void Setup_timer4() 
{
  // Timer4 Clock Prescaler to : 1
  // TCCR4B |= (0 << CS42) | (0 << CS41) | (1 << CS40);
  sbi (TCCR4B, CS40);
  cbi (TCCR4B, CS41);
  cbi (TCCR4B, CS42);

  // Timer4 PWM Mode set to Phase Correct PWM มันตั้งได้ 2 Register คือ A กับ B โดยจะตั้ง A เป็น High (Non-invert), B เป็น Low (Invert)
  //      MODE              COMnX1  COMnX2                        DesCription
  // Fast PWM                  1       0        Clear OCnX on compare, Set OCnX at BOTTOM (non-inverting)
  // Fast PWM                  1       1        Set OCnX on compare, Clear OCnX at BOTTOM (inverting)
  // PWM Phase/Freq Correct    1       0        Clear OCnX on compare Up-Cnt, Set OCnX on compare Down-Cnt
  // PWM Phase/Freq Correct    1       1        Set OCnX on compare Up-Cnt, Clear OCnX on compare Down-Cnt  
  // Timer2 PWM Mode set to Phase Correct PWM

  // TCCR4A |= (1 << COM4A1) | (0 << COM4A0); //non-inverting 
  cbi (TCCR4A, COM4A0);  // clear Compare Match
  sbi (TCCR4A, COM4A1);

  // TCCR4A |= (1 << COM4B1) | (1 << COM4B0); //inverting 
  sbi (TCCR4A, COM4B0); 
  sbi (TCCR4A, COM4B1);
  
  // Mode 1  / Phase Correct PWM
  sbi (TCCR4A, WGM40);  
  cbi (TCCR4A, WGM41);
  cbi (TCCR4B, WGM42);
  cbi (TCCR4B, WGM43);
}

void Setup_timer3() 
{
  // Timer3 Clock Prescaler to : 1
  // TCCR3B |= (0 << CS32) | (0 << CS31) | (1 << CS30);
  sbi (TCCR3B, CS30);
  cbi (TCCR3B, CS31);
  cbi (TCCR3B, CS32);            

  // Timer3 PWM Mode set to Phase Correct PWM มันตั้งได้ 2 Register คือ A กับ B โดยจะตั้ง A เป็น High (Non-invert), B เป็น Low (Invert)
  //      MODE              COMnX1  COMnX2                        DesCription
  // Fast PWM                  1       0        Clear OCnX on compare, Set OCnX at BOTTOM (non-inverting)
  // Fast PWM                  1       1        Set OCnX on compare, Clear OCnX at BOTTOM (inverting)
  // PWM Phase/Freq Correct    1       0        Clear OCnX on compare Up-Cnt, Set OCnX on compare Down-Cnt
  // PWM Phase/Freq Correct    1       1        Set OCnX on compare Up-Cnt, Clear OCnX on compare Down-Cnt  
  // Timer2 PWM Mode set to Phase Correct PWM

  // TCCR3A |= (1 << COM3A1) | (0 << COM3A0); //non-inverting 
  cbi (TCCR3A, COM3A0);  // clear Compare Match
  sbi (TCCR3A, COM3A1);

  // TCCR3A |= (1 << COM3B1) | (1 << COM3B0); //inverting 
  sbi (TCCR3A, COM3B0); 
  sbi (TCCR3A, COM3B1);
  
  // Mode 1  / Phase Correct PWM
  sbi (TCCR3A, WGM30);  
  cbi (TCCR3A, WGM31);
  cbi (TCCR3B, WGM32);
  cbi (TCCR3B, WGM33);
}

//Timer2 Interrupt Service at 31372,550 KHz = 32uSec

//FOUT = (M (REFCLK)) / (2 exp 32)
//Runtime : 8 microseconds
ISR(TIMER1_OVF_vect)
{
  
  phase_accumulator=phase_accumulator+tword_m; //Adds tuning M word to previoud phase accumulator. refer to DDS_calculator (from Martin Nawrath) for explination.
  current_count=phase_accumulator >> 24;     // use upper 8 bits of phase_accumulator as frequency information                      
  
  OCR1A = pgm_read_byte_near(sine256 + current_count); // read value fron ROM sine table and send to PWM
  OCR1B = OCR1A;

  OCR4A = pgm_read_byte_near(sine256 + (uint8_t)(current_count + phaseshift_1)); // read value fron ROM sine table and send to PWM, 120 Degree out of phase of PWM1
  OCR4B = OCR4A;

  OCR3A = pgm_read_byte_near(sine256 + (uint8_t)(current_count + phaseshift_2));// read value fron ROM sine table and send to PWM, 120 Degree out of phase of PWM2
  OCR3B = OCR3A;
  
  //increment variable ms4_delay every 4mS/125 =  milliseconds 32uS

  if(ms4_delay++ == 125) 
  {  
    c4ms++;
    ms4_delay=0; //reset count
   }   

}

I'm sorry if I did something wrong. Please give me some advice and help. I'm still a beginner.

jremington · November 26, 2023, 7:04am

Please explain the problem. What did you expect to happen, and what happened instead? What have you done to determine the nature of the problem?

Tell us which Arduino you are using.

The screen shot tells us nothing.

wongsagornkunlaphaet · November 26, 2023, 8:13am

I used Arduino Mega2560 in the simulation and the result is that pin 7 is not an inverter of pin 6 as programmed. which I want to come out like this picture
Reference_pwm
But in actual it happend

jremington · November 26, 2023, 4:50pm

Maybe the simulation is wrong. Test the function of Timer4 by itself, using a real Arduino, as well as the simulation.

Again, the screen shots tell us nothing. It wastes time and space to post a picture without a complete explanation of how it is to be interpreted.

wongsagornkunlaphaet · November 27, 2023, 4:08pm

Thank you for your reply. I use Timer 2 and its work! i found that problem is come from Timer number 4.

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