Created generic DDS class for tone generation, update AFSK to start the right timers.
This commit is contained in:
Stephen Olesen
parent
55c10c503b
commit
1117542411
28
AFSK.cpp
28
AFSK.cpp
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@ -14,6 +14,8 @@
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#define PPOOL_SIZE 2
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#define COMPARE_BITS 6
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#define ACCUMULATOR_SIZE 32
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#define ACCUMULATOR_BITS 24 // This is 2^10 bits used from accum
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//#undef PROGMEM
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//#define PROGMEM __attribute__((section(".progmem.data")))
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@ -44,15 +46,15 @@ volatile unsigned long lastTx = 0;
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volatile unsigned long lastTxEnd = 0;
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volatile unsigned long lastRx = 0;
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#define REFCLK 9600
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#define REFCLK 38400
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//#define REFCLK 31372.54902
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//#define REFCLK (16000000.0/510.0)
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//#define REFCLK 31200.0
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// 2200Hz = pow(2,32)*2200.0/refclk
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// 1200Hz = pow(2,32)*1200.0/refclk
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static const unsigned long toneStep[2] = {
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pow(2,32)*2200.0/REFCLK,
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pow(2,32)*1200.0/REFCLK
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(2200.0/REFCLK)*pow(2,ACCUMULATOR_SIZE),
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(1200.0/REFCLK)*pow(2,ACCUMULATOR_SIZE)
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};
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// Set to an arbitrary frequency
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@ -143,12 +145,7 @@ void AFSK::Encoder::process() {
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accumulator += toneStep[currentTone];
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uint8_t phAng = (accumulator >> ACCUMULATOR_BITS);
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/*if(toneVolume[currentTone] != 255) {
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OCR2B = pwm * toneVolume[currentTone] / 255;
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} else {*/
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// No volume scaling required
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OCR2B = pgm_read_byte_near(sinetable + phAng);
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/*}*/
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OCR2B = pgm_read_byte_near(sinetable + phAng)>>(8-COMPARE_BITS);
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}
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bool AFSK::Encoder::start() {
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@ -368,6 +365,19 @@ bool AFSK::Decoder::read() {
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void AFSK::Decoder::start() {
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// Do this in start to allocate our first packet
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currentPacket = pBuf.makePacket(PACKET_MAX_LEN);
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ASSR &= ~(_BV(EXCLK) | _BV(AS2));
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// Do non-inverting PWM on pin OC2B (arduino pin 3) (p.159).
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// OC2A (arduino pin 11) stays in normal port operation:
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// COM2B1=1, COM2B0=0, COM2A1=0, COM2A0=0
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// Mode 1 - Phase correct PWM
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TCCR2A = (TCCR2A | _BV(COM2B1)) & ~(_BV(COM2B0) | _BV(COM2A1) | _BV(COM2A0)) |
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_BV(WGM21) | _BV(WGM20);
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// No prescaler (p.162)
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TCCR2B = (TCCR2B & ~(_BV(CS22) | _BV(CS21))) | _BV(CS20) | _BV(WGM22);
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OCR2A = pow(2,COMPARE_BITS)-1;
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OCR2B = 0;
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// Configure the ADC and Timer1 to trigger automatic interrupts
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TCCR1A = 0;
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TCCR1B = _BV(CS11) | _BV(WGM13) | _BV(WGM12);
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@ -0,0 +1,82 @@
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#include <Arduino.h>
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#include "DDS.h"
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// To start the DDS, we use Timer1, set to the reference clock
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// We use Timer2 for the PWM output, running as fast as feasible
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void DDS::start() {
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// Use the clkIO clock rate
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ASSR &= ~(_BV(EXCLK) | _BV(AS2));
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// First, the timer for the PWM output
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// Setup the timer to use OC2B (pin 3) in fast PWM mode with a configurable top
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// Run it without the prescaler
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TCCR2A = (TCCR2A | _BV(COM2B1)) & ~(_BV(COM2B0) | _BV(COM2A1) | _BV(COM2A0)) |
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_BV(WGM21) | _BV(WGM20);
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TCCR2B = (TCCR2B & ~(_BV(CS22) | _BV(CS21))) | _BV(CS20) | _BV(WGM22);
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// Set the top limit, which will be our duty cycle accuracy.
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// Setting Comparator Bits smaller will allow for higher frequency PWM,
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// with the loss of resolution.
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OCR2A = pow(2,COMPARATOR_BITS)-1;
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OCR2B = 0;
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// Second, setup Timer1 to trigger the ADC interrupt
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// This lets us use decoding functions that run at the same reference
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// clock as the DDS.
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TCCR1B = _BV(CS11) | _BV(WGM13) | _BV(WGM12);
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TCCR1A = 0;
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ICR1 = ((F_CPU / 8) / DDS_REFCLK_DEAULT) - 1;
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// Configure the ADC here to automatically run and be triggered off Timer1
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ADMUX = _BV(REFS0) | _BV(ADLAR) | 0; // Channel 0, shift result left (ADCH used)
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DDRC &= ~_BV(0);
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PORTC &= ~_BV(0);
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DIDR0 |= _BV(0);
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ADCSRB = _BV(ADTS2) | _BV(ADTS1) | _BV(ADTS0);
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ADCSRA = _BV(ADEN) | _BV(ADSC) | _BV(ADATE) | _BV(ADIE) | _BV(ADPS2); // | _BV(ADPS0);
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}
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void DDS::stop() {
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// TODO: Stop the timers.
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}
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// Set our current sine wave frequency in Hz
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void DDS::setFrequency(unsigned short freq) {
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// Fo = (M*Fc)/2^N
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// M = (Fo/Fc)*2^N
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if(refclk == DDS_REFCLK_DEAULT) {
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// Try to use precalculated values if possible
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if(freq == 2200) {
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stepRate = (2200.0 / DDS_REFCLK_DEAULT) * pow(2,ACCUMULATOR_BITS);
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} else if (freq == 1200) {
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stepRate = (1200.0 / DDS_REFCLK_DEAULT) * pow(2,ACCUMULATOR_BITS);
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}
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} else {
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// Do the actual math instead.
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stepRate = (freq / refclk) * pow(2,ACCUMULATOR_BITS);
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}
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}
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void DDS::clockTick() {
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accumulator += stepRate;
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if(running) {
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if(tickDuration == 0) {
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OCR2B = 0;
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running = false;
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} else {
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OCR2B = getPhaseAngle();
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}
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// Reduce our playback duration by one tick
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tickDuration--;
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}
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}
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uint8_t DDS::getPhaseAngle() {
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#if ACCUMULATOR_BIT_SHIFT >= 24
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uint16_t phAng;
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#else
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uint8_t phAng;
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#endif
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phAng = (accumulator >> ACCUMULATOR_BIT_SHIFT);
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return pgm_read_byte_near(ddsSineTable + phAng)>>(8-COMPARATOR_BITS);
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}
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@ -0,0 +1,171 @@
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#ifndef _DDS_H_
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#define _DDS_H_
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#include <avr/pgmspace.h>
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#define SHORT_ACCUMULATOR
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#ifdef SHORT_ACCUMULATOR
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#define ACCUMULATOR_BITS 16
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#else
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#define ACCUMULATOR_BITS 32
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#endif
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#define COMPARATOR_BITS 6
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#define DDS_REFCLK_DEAULT 38400
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#define DDS_TABLE_LARGE
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#ifdef DDS_TABLE_LARGE
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#define ACCUMULATOR_BIT_SHIFT (ACCUMULATOR_BITS-10)
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static const uint8_t ddsSineTable[1024] PROGMEM = {
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128,128,129,130,131,131,132,133,134,135,135,136,137,138,138,139,
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140,141,142,142,143,144,145,145,146,147,148,149,149,150,151,152,
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152,153,154,155,155,156,157,158,158,159,160,161,162,162,163,164,
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165,165,166,167,167,168,169,170,170,171,172,173,173,174,175,176,
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176,177,178,178,179,180,181,181,182,183,183,184,185,186,186,187,
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188,188,189,190,190,191,192,192,193,194,194,195,196,196,197,198,
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198,199,200,200,201,202,202,203,203,204,205,205,206,207,207,208,
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208,209,210,210,211,211,212,213,213,214,214,215,215,216,217,217,
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218,218,219,219,220,220,221,221,222,222,223,224,224,225,225,226,
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226,227,227,228,228,228,229,229,230,230,231,231,232,232,233,233,
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234,234,234,235,235,236,236,236,237,237,238,238,238,239,239,240,
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240,240,241,241,241,242,242,242,243,243,243,244,244,244,245,245,
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245,246,246,246,246,247,247,247,248,248,248,248,249,249,249,249,
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250,250,250,250,250,251,251,251,251,251,252,252,252,252,252,252,
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253,253,253,253,253,253,253,254,254,254,254,254,254,254,254,254,
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254,254,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
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255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,254,
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254,254,254,254,254,254,254,254,254,254,253,253,253,253,253,253,
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253,252,252,252,252,252,252,251,251,251,251,251,250,250,250,250,
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250,249,249,249,249,248,248,248,248,247,247,247,246,246,246,246,
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245,245,245,244,244,244,243,243,243,242,242,242,241,241,241,240,
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240,240,239,239,238,238,238,237,237,236,236,236,235,235,234,234,
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234,233,233,232,232,231,231,230,230,229,229,228,228,228,227,227,
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226,226,225,225,224,224,223,222,222,221,221,220,220,219,219,218,
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218,217,217,216,215,215,214,214,213,213,212,211,211,210,210,209,
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208,208,207,207,206,205,205,204,203,203,202,202,201,200,200,199,
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198,198,197,196,196,195,194,194,193,192,192,191,190,190,189,188,
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188,187,186,186,185,184,183,183,182,181,181,180,179,178,178,177,
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176,176,175,174,173,173,172,171,170,170,169,168,167,167,166,165,
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165,164,163,162,162,161,160,159,158,158,157,156,155,155,154,153,
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152,152,151,150,149,149,148,147,146,145,145,144,143,142,142,141,
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140,139,138,138,137,136,135,135,134,133,132,131,131,130,129,128,
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128,127,126,125,124,124,123,122,121,120,120,119,118,117,117,116,
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115,114,113,113,112,111,110,110,109,108,107,106,106,105,104,103,
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103,102,101,100,100,99,98,97,97,96,95,94,93,93,92,91,
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90,90,89,88,88,87,86,85,85,84,83,82,82,81,80,79,
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79,78,77,77,76,75,74,74,73,72,72,71,70,69,69,68,
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67,67,66,65,65,64,63,63,62,61,61,60,59,59,58,57,
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57,56,55,55,54,53,53,52,52,51,50,50,49,48,48,47,
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47,46,45,45,44,44,43,42,42,41,41,40,40,39,38,38,
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37,37,36,36,35,35,34,34,33,33,32,31,31,30,30,29,
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29,28,28,27,27,27,26,26,25,25,24,24,23,23,22,22,
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21,21,21,20,20,19,19,19,18,18,17,17,17,16,16,15,
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15,15,14,14,14,13,13,13,12,12,12,11,11,11,10,10,
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10,9,9,9,9,8,8,8,7,7,7,7,6,6,6,6,
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5,5,5,5,5,4,4,4,4,4,3,3,3,3,3,3,
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2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,
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1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
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1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,
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2,3,3,3,3,3,3,4,4,4,4,4,5,5,5,5,
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5,6,6,6,6,7,7,7,7,8,8,8,9,9,9,9,
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10,10,10,11,11,11,12,12,12,13,13,13,14,14,14,15,
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15,15,16,16,17,17,17,18,18,19,19,19,20,20,21,21,
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21,22,22,23,23,24,24,25,25,26,26,27,27,27,28,28,
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29,29,30,30,31,31,32,33,33,34,34,35,35,36,36,37,
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37,38,38,39,40,40,41,41,42,42,43,44,44,45,45,46,
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47,47,48,48,49,50,50,51,52,52,53,53,54,55,55,56,
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57,57,58,59,59,60,61,61,62,63,63,64,65,65,66,67,
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67,68,69,69,70,71,72,72,73,74,74,75,76,77,77,78,
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79,79,80,81,82,82,83,84,85,85,86,87,88,88,89,90,
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90,91,92,93,93,94,95,96,97,97,98,99,100,100,101,102,
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103,103,104,105,106,106,107,108,109,110,110,111,112,113,113,114,
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115,116,117,117,118,119,120,120,121,122,123,124,124,125,126,127
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};
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#else
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#define ACCUMULATOR_BIT_SHIFT (ACCUMULATOR_BITS-8)
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static const uint8_t ddsSineTable[256] PROGMEM = {
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128,131,134,137,140,143,146,149,152,155,158,162,165,167,170,173,
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176,179,182,185,188,190,193,196,198,201,203,206,208,211,213,215,
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218,220,222,224,226,228,230,232,234,235,237,238,240,241,243,244,
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245,246,248,249,250,250,251,252,253,253,254,254,254,255,255,255,
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255,255,255,255,254,254,254,253,253,252,251,250,250,249,248,246,
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245,244,243,241,240,238,237,235,234,232,230,228,226,224,222,220,
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218,215,213,211,208,206,203,201,198,196,193,190,188,185,182,179,
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176,173,170,167,165,162,158,155,152,149,146,143,140,137,134,131,
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128,124,121,118,115,112,109,106,103,100,97,93,90,88,85,82,
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79,76,73,70,67,65,62,59,57,54,52,49,47,44,42,40,
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37,35,33,31,29,27,25,23,21,20,18,17,15,14,12,11,
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10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,
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0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,
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10,11,12,14,15,17,18,20,21,23,25,27,29,31,33,35,
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37,40,42,44,47,49,52,54,57,59,62,65,67,70,73,76,
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79,82,85,88,90,93,97,100,103,106,109,112,115,118,121,124
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};
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#endif /* DDS_TABLE_LARGE */
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class DDS {
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public:
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DDS(): refclk(DDS_REFCLK_DEAULT), accumulator(0), running(false) {};
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void start();
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const bool isRunning() { return running; };
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void stop();
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// Start the PWM output, or stop it
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void on() {
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running = true;
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}
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// Provide a duration in ms for the tone
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void on(unsigned short duration) {
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// Duration in ticks from milliseconds is:
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// t = (1/refclk)
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tickDuration = duration / (1000.0/refclk);
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running = true;
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}
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void off() {
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running = false;
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}
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// Generate a tone for a specific amount of time
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void play(unsigned short freq, unsigned short duration) {
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setFrequency(freq);
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on(duration);
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}
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// Blocking version
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void playWait(unsigned short freq, unsigned short duration) {
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setFrequency(freq);
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on(duration);
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delay(duration * 1000);
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}
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// Our maximum clock isn't very high, so our highest
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// frequency supported will fit in a short.
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void setFrequency(unsigned short freq);
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// Adjustable reference clock
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void setReferenceClock(unsigned long ref);
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uint8_t getPhaseAngle();
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void clockTick();
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private:
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bool running;
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unsigned long tickDuration;
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#ifdef SHORT_ACCUMULATOR
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unsigned short accumulator;
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unsigned short stepRate;
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unsigned short refclk;
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#else
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unsigned long accumulator;
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unsigned long stepRate;
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unsigned long refclk;
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#endif
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static DDS *sDDS;
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};
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#endif /* _DDS_H_ */
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