/*
Tone generator
v1 use timer, and toggle any digital pin in ISR
funky duration from arduino version
TODO use FindMckDivisor?
timer selected will preclude using associated pins for PWM etc.
could also do timer/pwm hardware toggle where caller controls duration
*/
// timers TC0 TC1 TC2 channels 0-2 ids 0-2 3-5 6-8 AB 0 1
// use TC1 channel 0
#define TONE_TIMER TC0
#define TONE_CHNL 0
#define TONE_IRQ TC0_IRQn
// TIMER_CLOCK4 84MHz/128 with 16 bit counter give 10 Hz to 656KHz
// piano 27Hz to 4KHz
static uint8_t pinEnabled[PINS_COUNT];
static uint8_t TCChanEnabled = 0;
static boolean pin_state = false ;
static Tc *chTC = TONE_TIMER;
static uint32_t chNo = TONE_CHNL;
volatile static int32_t toggle_count;
static uint32_t tone_pin;
// frequency (in hertz) and duration (in milliseconds).
void tone(uint32_t ulPin, uint32_t frequency, int32_t duration)
{
const uint32_t rc = VARIANT_MCK / 256 / frequency;
tone_pin = ulPin;
toggle_count = 0; // strange wipe out previous duration
if (duration > 0 ) toggle_count = 2 * frequency * duration / 1000;
else toggle_count = -1;
if (!TCChanEnabled) {
pmc_set_writeprotect(false);
pmc_enable_periph_clk((uint32_t)TONE_IRQ);
TC_Configure(chTC, chNo,
TC_CMR_TCCLKS_TIMER_CLOCK4 |
TC_CMR_WAVE | // Waveform mode
TC_CMR_WAVSEL_UP_RC ); // Counter running up and reset when equals to RC
chTC->TC_CHANNEL[chNo].TC_IER=TC_IER_CPCS; // RC compare interrupt
chTC->TC_CHANNEL[chNo].TC_IDR=~TC_IER_CPCS;
NVIC_EnableIRQ(TONE_IRQ);
TCChanEnabled = 1;
}
if (!pinEnabled[ulPin]) {
pinMode(ulPin, OUTPUT);
pinEnabled[ulPin] = 1;
}
TC_Stop(chTC, chNo);
TC_SetRC(chTC, chNo, rc); // set frequency
TC_Start(chTC, chNo);
}
void noTone(uint32_t ulPin)
{
TC_Stop(chTC, chNo); // stop timer
digitalWrite(ulPin,LOW); // no signal on pin
}
// timer ISR TC0 ch 0
void TC0_Handler ( void ) {
TC_GetStatus(TC0, 0);
if (toggle_count != 0){
// toggle pin TODO better
digitalWrite(tone_pin,pin_state= !pin_state);
if (toggle_count > 0) toggle_count--;
} else {
noTone(tone_pin);
}
}
