18-12-2023, 02:35
Kod:
// This code demonstrates how to generate two output signals
// with variable phase shift between them using an AVR Timer
// The output shows up on Arduino pin 9 and 10 (these are connected to the Timer1 A and B outputs respectively)
// More AVR Timer Tricks at http://josh.com
void setup() {
pinMode( 9 , OUTPUT ); // Arduino Pin 9 = OCR1A
pinMode( 10 , OUTPUT ); // Arduino Pin 10 = OCR1B
}
// prescaler of 1 will get us 4MHz - 488Hz
// User a higher prescaler for lower frequencies
#define PRESCALER 1
#define PRESCALER_BITS 0x01
// Output phase shifted waveforms on Arduino Pins 9 & 10
// half_period = 1/2 the period of both waveform in clock ticks (16Mhz clock default) note that the larger this number the lower the freq annd the more phase shift resolution you get
// shift = number of ticks delay between leading waveform and trailing. Must be < half_period
// invert_b- should we initially invert B? 1=A leads B, 0=B leads A
// To be completely out of phase, set shift=0 and invert_b=1
void startWaveforms( uint16_t half_period , uint16_t shift , byte invert_b ) {
TCCR1B = 0; // Turn off counter if it is on. Makes sure nothing happens while we are getting things set up.
// Leaves us in Normal mode, where we can do a Force Compare Match.
// First we need to get the phases of the two outputs set up correctly
// Set regs so when we force a compare it will match. This is the only way to set the state of the outputs on this chip.
//-------------------------------
// OCR2A = 127; //50% duty cycle
//OCR2B = 64; //about 25% duty cycle
OCR1A = 110;
OCR1B = 0;
TCNT1 = 0;
if (invert_b) {
TCCR1A = _BV( COM1A1 ) | _BV( COM1B1 ) | _BV( COM1B0 ); // Output A=0 and B=1 on compare match (which we will force presently)
} else {
TCCR1A = _BV( COM1A1 ) | _BV( COM1B1 ); // Output A=0 and B=0 on compare match (which we will force presently)
}
// Force a compare.
// If polarity=0, then make A=1, B=1
// If polarity=1, then make A=1, B=0
TCCR1C = _BV( FOC1A ) | _BV( FOC1B );
// Now that polarity is established, we can set things ready to run
// Both outputs into toggle mode. The output will toggle each time there is a compare match.
// Since they both toggle once per period, they will stay in whatever polarity they start in.
TCCR1A = _BV( COM1A0 ) | _BV( COM1B0 );
// OCR1A = 0;
OCR1A = 110;
OCR1B = shift;
// Set the counter to roll over on the first step. This will force a match when it rolls to 0.
TCNT1 = 0xffff;
// In CTC Waveform Generation Mode
// TCNT counts up to ICR1 then resets back to 0
ICR1 = half_period - 1; // We subtract 1 becuase when we get to ICR1 then on the next tick we go back to 0, so will make `period` ticks per cycle total.
// Turn on timer now
// Mode=CTC, clock=clkio/1 (no prescaling)
// Note: you could use a prescaller here for lower frequencies
TCCR1B = _BV( WGM13) | _BV( WGM12) | _BV( CS10 );
}
// Stop output, make both outputs low.
void stopWaveforms() {
TCCR1A = _BV( COM1A1 ) | _BV( COM1B1 ) ; // Output A=0 and B=0 on next compare match
}
// Min frequency is 16mhz / 65536 ticks per timer cyclke /2 timer cycles per waveform cycle ~= 122 hz
// freq_hz is frequency in hertz from 122 to 4,000,000
// shift_deg is phase shift between output A and output B in degrees (values outside -180 to +180 are normalized)
// Note that at frequencies above 44KHz you will loose precision on phase shift. At 4Mhz, everything is rounded to just 0 or +/-90 degrees.
// Note that all timing happens in 1/16Mhz increments, so frequencies that do not land on integer multipules of that will be aproximiate.
// Use startWaveforms() directly for more precise control.
void startQuadrature( unsigned long freq_hz , int shift_deg ) {
// This assumes prescaler = 1. For lower freqnecies, use a larger prescaler.
unsigned long clocks_per_toggle = (F_CPU / freq_hz) / 2; // /2 becuase it takes 2 toggles to make a full wave
// Normalize into 0-360 degrees
while ( shift_deg < 0 ) {
shift_deg += 360;
}
while ( shift_deg >= 360 ) {
shift_deg -= 360;
}
// Normalize a shift of more than 180 degress
byte invert = 0 ;
if (shift_deg >= 180 ) {
invert = 1 ; // Invert direction
shift_deg -= 180;
}
unsigned long offset_clocks;
offset_clocks = (clocks_per_toggle * shift_deg) / 180UL; // Do multiplication first to save precision
startWaveforms( clocks_per_toggle , offset_clocks , invert );
}
void stopQuadrature() {
stopWaveforms();
}
void loop() {
// 10KHz, A and B exactly out of phase
startQuadrature( 10000 , 180 ); //(-180 same result)
delay(10);
// stopQuadrature();
//delay(1000);
}Witam
Czy ktoś wie jak zmienić szerokość impulsu w tym generatorze?
