Restarting at 0

[prasadbodas2000]

I am trying this useful code to control input signals to two MOSFET drivers IR2104 which in turn control four MOSFETs in a H bridge. I am incorporating a start and stop switch in arduino when pressed the spwm shall start or stop. While starting I require that the zero point of the Sine wave will start. How can this be achieved? please help. I am aware of only basic programming in arduino and not much clarity about interrupts.

[prasadbodas2000]

More info on the question- currently I am switching shutdown pin of the IR2104 chips from arduino to achieve on-off of the H bridge

[Irev-Dev]

What have you tried so far? Where are you getting stuck?

[prasadbodas2000]

Thank you for your response.
This is the circuit driven from arduino digital 9 and 10 pins as pulse 1 and pulse 2. Digital pin 8 toggles the shutdown pin low to switch off the ir2104 and high to switch on.
When switching on after a switch off and since timers in arduino are already running at whatever stage it is likely that the upper MOSFET gets triggered, but the bootstrap cap may not be charged yet and the upper MOSFET may get in partial conduction and eventually destroyed. This happened intermittently and I ended up shorting any one side of the bridge. So it needs that when shutdown pin is put high at that time first few pulses need to be 0 on both digital pins 9 and 10, that will put both low side MOSFETs in conduction and will give a chance for bootstrap cap to get charged enough.

[T31328]

Respectfully Sir In this Code I want to change the output Sinusoidal frequency of 10kHZ can u suggest me any changes?

#include <avr/io.h>
#include <avr/interrupt.h>

#define LookupEntries (512)

static int microMHz = 16; // clock frequency in MHz
static int freq, amp = 25000;// Sinusoidal frequency
static long int period; // Period of PWM in clock cycles. 1600 gives 10KHz.
static unsigned int lookUp[LookupEntries];
static char theTCCR1A = 0b10000010; //varible for TCCR1A
static unsigned long int phaseinc, switchFreq;
static double phaseincMult;

int setFreq(int freq); //set in Hertz
int setSwitchFreq(int sfreq); //set in Hertz
int setAmp(float _amp); //set in % (0 - 100)
void makeLookUp(void);
void registerInit(void);

void setup(){
Serial.begin(9600);
makeLookUp();
setSwitchFreq(80000);
setFreq(25000);
setAmp(25000);
registerInit();
}

void loop(){
/*
The code in the loop reads analog values from pins A1 and A2 so that potentiometers can be connected.
These values are used to vary the amplitude and frequency of the sine wave.
The switching frequency also toggles between 5 and 15Khz.
*/
static int ampVal, freqVal, anologVal;

anologVal = analogRead(A0);
if(anologVal > freqVal1.01 || anologVal < freqVal0.99){
freqVal = anologVal;
setFreq(map(freqVal, 0, 25000, 5, 300));
Serial.println("phaseinc");
Serial.print(phaseinc>>23);
Serial.print(".");
Serial.print(phaseinc&0x007FFFFF);
Serial.print("\n");
}

anologVal = analogRead(A1);
if(anologVal > ampVal1.01 || anologVal < ampVal0.99){
ampVal = anologVal;
setAmp(map(ampVal, 0, 25000, 0, 100));
Serial.println("amplitude");
Serial.println(amp);
}

delay(20);
static char cnt = 0;
cnt++;
if(cnt == 100){
setSwitchFreq(80000);
cnt = 0;
} else if(cnt == 50){
setSwitchFreq(5000);
}
}

ISR(TIMER1_OVF_vect){
static unsigned long int phase, lastphase;
static char delay1, trig = LOW;

phase += phaseinc;

if(delay1 == 1){
theTCCR1A ^= 0b10100000;// Toggle connect and disconnect of compare output A and B.
TCCR1A = theTCCR1A;
delay1 = 0;
}
else if((phase>>31 != lastphase>>31) && !(phase>>31)){
delay1++;
trig = !trig;
digitalWrite(13,trig);
}

lastphase = phase;
OCR1A = OCR1B = ((lookUp[phase >> 23]*period) >> 12)*amp >> 10;
}

int setFreq(int _freq){
if(_freq < 0 || _freq > 25000){ // returns -1 if the frequency value is invalid
return 0;
} else {
freq = _freq;
phaseinc = (unsigned long int) phaseincMult*_freq;
return 1;
}
}

int setSwitchFreq(int sfreq){
double temp;

if(sfreq <= 0 || sfreq > 80000){
return 0;
} else {
switchFreq = sfreq;
period = microMHz1e6/sfreq;
//sindevisionsdecimalbits/1MHz =
//10242^23/1e6 = 8,589.934592
phaseincMult = (double) period8589.934592/microMHz;
phaseinc = (unsigned long int) phaseincMult*freq;
ICR1 = period;
}
}

int setAmp(float _amp)
{
if(_amp < 0 || _amp > 25000){
return 0;
} else {
amp = map(_amp,0,100,0,25000);
return 1;
}
}

void makeLookUp(void){
double temp;

cli(); //disable global interupts while lookup table is made
TCCR1A = 0b00000010; //disconnect compare A and B while lookup table is generated

for(int i = 0; i < LookupEntries; i++){ // Generating the look up table.
  temp = sin(i*M_PI/LookupEntries)*4096;
  lookUp[i] = (int)(temp+0.5);       // Round to integer.    
}

TCCR1A = theTCCR1A; // reconnect compare outputs
sei(); //re-enable interupts now that table has been made

}

void registerInit(void){
// Register initilisation, see datasheet for more detail.
TCCR1A = theTCCR1A; // 0b10000010;
/*10 clear on match, set at BOTTOM for compA.
00 compB disconected initially, toggled later to clear on match, set at BOTTOM.
00
10 WGM1 1:0 for waveform 15.
*/
TCCR1B = 0b00011001;
/*000
11 WGM1 3:2 for waveform 15.
001 no prescale on the counter.
*/
TIMSK1 = 0b00000001;
/*0000000
1 TOV1 Flag interrupt enable.
*/
sei(); // Enable global interrupts.
// Set outputs pins.
DDRB = 0b00000110; // Set PB1 and PB2 as outputs.
pinMode(13, OUTPUT); // Set trigger pin to output
}