56 lines
3.0 KiB
C++
56 lines
3.0 KiB
C++
// ---------------------------------------------------------------------------
|
|
// Created by Tim Eckel - teckel@leethost.com
|
|
// Copyright 2015 License: GNU GPL v3 http://www.gnu.org/licenses/gpl-3.0.html
|
|
//
|
|
// See "toneAC2.h" for purpose, syntax, version history, links, and more.
|
|
// ---------------------------------------------------------------------------
|
|
|
|
#include "toneAC2.h"
|
|
|
|
unsigned long _tAC2_time; // Used to track end note with timer when playing note in the background.
|
|
volatile uint8_t *_pinMode1; // Pin modes.
|
|
uint8_t _pinMask1 = 0; // Bitmask for pins.
|
|
volatile uint8_t *_pinOutput1; // Output port registers for each pin.
|
|
int _tAC2_prescale[] = { 2, 16, 64, 128, 256, 512, 2048 }; // Prescaler.
|
|
|
|
void toneAC2(uint8_t pin1, unsigned int frequency, unsigned long length, uint8_t background) {
|
|
long top;
|
|
uint8_t prescaler;
|
|
|
|
for (prescaler = 1; prescaler < 8; prescaler++) { // Find the appropriate prescaler
|
|
top = F_CPU / (long) frequency / (long) _tAC2_prescale[prescaler - 1] - 1; // Calculate the top.
|
|
if (top < 256) break; // Fits, break out of for loop.
|
|
}
|
|
if (top > 255) { noToneAC2(); return; } // Frequency is out of range, turn off sound and return.
|
|
|
|
if (length > 0) _tAC2_time = millis() + length - 1; else _tAC2_time = 0xFFFFFFFF; // Set when the note should end, or play "forever".
|
|
|
|
if (_pinMask1 == 0) { // This gets the port registers and bitmaps for the two pins and sets the pins to output mode.
|
|
_pinMask1 = digitalPinToBitMask(pin1); // Get the port register bitmask for pin 1.
|
|
_pinOutput1 = portOutputRegister(digitalPinToPort(pin1)); // Get the output port register for pin 1.
|
|
_pinMode1 = (uint8_t *) portModeRegister(digitalPinToPort(pin1)); // Get the port mode register for pin 1.
|
|
*_pinMode1 |= _pinMask1; // Set pin 1 to Output mode.
|
|
}
|
|
|
|
OCR2A = top; // Set the top.
|
|
if (TCNT2 > top) TCNT2 = top; // Counter over the top, put within range.
|
|
TCCR2B = _BV(WGM22) | prescaler; // Set Fast PWM and prescaler.
|
|
TCCR2A = _BV(WGM20) | _BV(WGM21); // Fast PWM and normal port operation, OC2A/OC2B disconnected.
|
|
TIMSK2 &= ~_BV(OCIE2A); // Stop timer 2 interrupt while we set the pin states.
|
|
TIMSK2 |= _BV(OCIE2A); // Activate the timer interrupt.
|
|
|
|
if (length > 0 && !background) { delay(length); noToneAC2(); } // Just a simple delay, doesn't return control till finished.
|
|
}
|
|
|
|
void noToneAC2() {
|
|
TIMSK2 &= ~_BV(OCIE2A); // Remove the timer interrupt.
|
|
TCCR2B = _BV(CS22); // Default clock prescaler of 64.
|
|
TCCR2A = _BV(WGM20); // Set to defaults so PWM can work like normal (PWM, phase corrected, 8bit).
|
|
*_pinMode1 &= ~_pinMask1; // Set pin 1 to INPUT.
|
|
_pinMask1 = 0; // Flag so we know note is no longer playing.
|
|
}
|
|
|
|
ISR(TIMER2_COMPA_vect) { // Timer interrupt vector.
|
|
if (millis() > _tAC2_time) noToneAC2(); // Check to see if it's time for the note to end.
|
|
*_pinOutput1 ^= _pinMask1; // Toggle the pin 1 state.
|
|
} |