124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
/*
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2023 Based on:
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https://github.com/arduino/ArduinoCore-avr/blob/a7edf4d66f66d42ebb7e166762ac7c11cb299a3f/cores/arduino/Tone.cpp
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A Tone Generator Library
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Written by Brett Hagman
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <avr/interrupt.h>
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// Pin for buzzer: PD0
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#define BZ_PIN_PORT PORTD
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#define BZ_PIN_DDR DDRD
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#define BZ_PIN_MASK (1<<1)
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volatile long toggle_count;
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static void toneBegin(void)
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{
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// Timer 1
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//TCCR1A = 0;
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//TCCR1B = 0;
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// CTC mode
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//TCCR1B |= WGM12;
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TCCR1B |= _BV(WGM12);
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// No prescaling
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//TCCR1B |= CS10;
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TCCR1B |= _BV(CS10);
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BZ_PIN_DDR |= BZ_PIN_MASK;
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BZ_PIN_PORT |= BZ_PIN_MASK;
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}
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// frequency (in hertz) and duration (in milliseconds).
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void tone(unsigned int frequency, unsigned long duration)
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{
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uint8_t prescalarbits = 0b001;
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uint32_t ocr = 0;
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toneBegin();
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// Set the pinMode as OUTPUT
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BZ_PIN_DDR |= BZ_PIN_MASK;
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// two choices for the 16 bit timers: ck/1 or ck/64
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ocr = F_CPU / frequency / 2 - 1;
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prescalarbits = 0b001; // CLKio/1
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if (ocr > 0xffff) {
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ocr = F_CPU / frequency / 2 / 64 - 1;
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prescalarbits = 0b011; // CLKio/64
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}
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TCCR1B = (TCCR1B & 0b11111000) | prescalarbits;
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// Calculate the toggle count
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if (duration > 0) {
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toggle_count = 2 * frequency * duration / 1000;
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} else {
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toggle_count = -1;
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}
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uint8_t sreg = SREG;
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cli();
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OCR1AH = (ocr >> 8) & 0xff;
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OCR1AL = ocr & 0xff;
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SREG = sreg;
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// enable interrupt
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TIMSK1 |= (1<<OCIE1A);
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}
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// XXX: this function only works properly for timer 2 (the only one we use
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// currently). for the others, it should end the tone, but won't restore
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// proper PWM functionality for the timer.
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void disableTimer(void)
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{
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// disable interrupt
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TIMSK1 &= ~(1<<OCIE1A);
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TCCR1A = 0;
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TCCR1B = 0;
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uint8_t sreg = SREG;
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cli();
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OCR1AH = 0;
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OCR1AL = 0;
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SREG = sreg;
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}
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void noTone(void)
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{
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disableTimer();
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BZ_PIN_PORT &= ~(BZ_PIN_MASK);
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}
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ISR(TIMER1_COMPA_vect)
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{
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if (toggle_count != 0) {
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// toggle the pin
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BZ_PIN_PORT ^= BZ_PIN_MASK;
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if (toggle_count > 0)
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toggle_count--;
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} else {
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disableTimer();
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BZ_PIN_PORT &= ~(BZ_PIN_MASK);
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}
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}
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