forked from CodeForCuritiba/WeAreAllSmart
-
Notifications
You must be signed in to change notification settings - Fork 0
/
NewTone.cpp
49 lines (41 loc) · 2.46 KB
/
NewTone.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
// ---------------------------------------------------------------------------
// Created by Tim Eckel - teckel@leethost.com
// Copyright 2013 License: GNU GPL v3 http://www.gnu.org/licenses/gpl-3.0.html
//
// See "NewTone.h" for purpose, syntax, version history, links, and more.
// ---------------------------------------------------------------------------
#include "NewTone.h"
unsigned long _nt_time; // Time note should end.
uint8_t _pinMask = 0; // Pin bitmask.
volatile uint8_t *_pinOutput; // Output port register
void NewTone(uint8_t pin, unsigned long frequency, unsigned long length) {
uint8_t prescaler = _BV(CS10); // Try using prescaler 1 first.
unsigned long top = F_CPU / frequency / 4 - 1; // Calculate the top.
if (top > 65535) { // If not in the range for prescaler 1, use prescaler 256 (61 Hz and lower @ 16 MHz).
prescaler = _BV(CS12); // Set the 256 prescaler bit.
top = top / 256 - 1; // Calculate the top using prescaler 256.
}
if (length > 0) _nt_time = millis() + length; else _nt_time = 0xFFFFFFFF; // Set when the note should end, or play "forever".
if (_pinMask == 0) {
_pinMask = digitalPinToBitMask(pin); // Get the port register bitmask for the pin.
_pinOutput = portOutputRegister(digitalPinToPort(pin)); // Get the output port register for the pin.
uint8_t *_pinMode = (uint8_t *) portModeRegister(digitalPinToPort(pin)); // Get the port mode register for the pin.
*_pinMode |= _pinMask; // Set the pin to Output mode.
}
ICR1 = top; // Set the top.
if (TCNT1 > top) TCNT1 = top; // Counter over the top, put within range.
TCCR1B = _BV(WGM13) | prescaler; // Set PWM, phase and frequency corrected (ICR1) and prescaler.
TCCR1A = _BV(COM1B0);
TIMSK1 |= _BV(OCIE1A); // Activate the timer interrupt.
}
void noNewTone(uint8_t pin) {
TIMSK1 &= ~_BV(OCIE1A); // Remove the timer interrupt.
TCCR1B = _BV(CS11); // Default clock prescaler of 8.
TCCR1A = _BV(WGM10); // Set to defaults so PWM can work like normal (PWM, phase corrected, 8bit).
*_pinOutput &= ~_pinMask; // Set pin to LOW.
_pinMask = 0; // Flag so we know note is no longer playing.
}
ISR(TIMER1_COMPA_vect) { // Timer interrupt vector.
if (millis() >= _nt_time) noNewTone(); // Check to see if it's time for the note to end.
*_pinOutput ^= _pinMask; // Toggle the pin state.
}