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Change amplitude scaling. Go back to refclk for ICR1. Added phase changes.

This commit is contained in:
Stephen Olesen 2015-07-02 18:04:12 -06:00
parent 0e9a549f56
commit 2152100873
2 changed files with 27 additions and 6 deletions
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21
DDS.cpp
View File

@ -42,8 +42,8 @@ void DDS::start() {
// clock as the DDS. // clock as the DDS.
TCCR1B = _BV(CS11) | _BV(WGM13) | _BV(WGM12); TCCR1B = _BV(CS11) | _BV(WGM13) | _BV(WGM12);
TCCR1A = 0; TCCR1A = 0;
//ICR1 = ((F_CPU / 8) / refclk) - 1; ICR1 = ((F_CPU / 8) / refclk) - 1;
ICR1 = ((F_CPU / 8) / 9600) - 1; //ICR1 = ((F_CPU / 8) / 9600) - 1;
// Configure the ADC here to automatically run and be triggered off Timer1 // Configure the ADC here to automatically run and be triggered off Timer1
ADMUX = _BV(REFS0) | _BV(ADLAR) | 0; // Channel 0, shift result left (ADCH used) ADMUX = _BV(REFS0) | _BV(ADLAR) | 0; // Channel 0, shift result left (ADCH used)
@ -77,8 +77,21 @@ void DDS::setFrequency(unsigned short freq) {
} }
} }
// Degrees should be between -360 and +360 (others don't make much sense)
void DDS::setPhaseDeg(int16_t degrees) {
accumulator = degrees * (pow(2,ACCUMULATOR_BITS)/360.0);
}
void DDS::changePhaseDeg(int16_t degrees) {
accumulator += degrees * (pow(2,ACCUMULATOR_BITS)/360.0);
}
// TODO: Clean this up a bit.. // TODO: Clean this up a bit..
void DDS::clockTick() { void DDS::clockTick() {
/* if(running) {
accumulator += stepRate;
OCR2A = getDutyCycle();
}
return;*/
if(running) { if(running) {
accumulator += stepRate; accumulator += stepRate;
if(timeLimited && tickDuration == 0) { if(timeLimited && tickDuration == 0) {
@ -129,5 +142,7 @@ uint8_t DDS::getDutyCycle() {
phAng = (accumulator >> ACCUMULATOR_BIT_SHIFT); phAng = (accumulator >> ACCUMULATOR_BIT_SHIFT);
uint8_t position = pgm_read_byte_near(ddsSineTable + phAng)>>(8-COMPARATOR_BITS); uint8_t position = pgm_read_byte_near(ddsSineTable + phAng)>>(8-COMPARATOR_BITS);
// Apply scaling and return // Apply scaling and return
return position >> amplitude; uint16_t scaled = position;
scaled *= amplitude;
return scaled>>8;
} }

12
DDS.h
View File

@ -42,7 +42,7 @@
// This is how often we'll perform a phase advance, as well as ADC sampling // This is how often we'll perform a phase advance, as well as ADC sampling
// rate. The higher this value, the smoother the output wave will be, at the // rate. The higher this value, the smoother the output wave will be, at the
// expense of CPU time. It maxes out around 62000 (TBD) // expense of CPU time. It maxes out around 62000 (TBD)
#define DDS_REFCLK_DEFAULT 9600 #define DDS_REFCLK_DEFAULT 38400
// As each Arduino crystal is a little different, this can be fine tuned to // As each Arduino crystal is a little different, this can be fine tuned to
// provide more accurate frequencies. Adjustments in the range of hundreds // provide more accurate frequencies. Adjustments in the range of hundreds
// is a good start. // is a good start.
@ -193,10 +193,16 @@ public:
// frequency supported will fit in a short. // frequency supported will fit in a short.
void setFrequency(unsigned short freq); void setFrequency(unsigned short freq);
// Handle phase shifts
void setPhaseDeg(int16_t degrees);
void changePhaseDeg(int16_t degrees);
// Adjustable reference clock. This shoud be done before the timers are // Adjustable reference clock. This shoud be done before the timers are
// started, or they will need to be restarted. Frequencies will need to // started, or they will need to be restarted. Frequencies will need to
// be set again to use the new clock. // be set again to use the new clock.
void setReferenceClock(unsigned long ref); void setReferenceClock(unsigned long ref) {
refclk = ref;
}
unsigned long getReferenceClock() { unsigned long getReferenceClock() {
return refclk; return refclk;
} }
@ -206,7 +212,7 @@ public:
// Set a scaling factor. To keep things quick, this is a power of 2 value. // Set a scaling factor. To keep things quick, this is a power of 2 value.
// Set it with 0 for lowest (which will be off), 8 is highest. // Set it with 0 for lowest (which will be off), 8 is highest.
void setAmplitude(unsigned char amp) { void setAmplitude(unsigned char amp) {
amplitude = 8 - amp; amplitude = amp;
} }
// This is the function called by the ADC_vect ISR to produce the tones // This is the function called by the ADC_vect ISR to produce the tones