waveblender/timer.c

#include <stdint.h>
#include "system.h"
#include "led.h"
#include "timer.h"
#include <stdlib.h>
#include "settings.h"

#define S_PER_MINUTE (60)

extern uint32_t cpu_freq;

void (*beat_callback)(uint32_t b) = NULL;

void timer_set_beat_callback(void (*b_cb)(uint32_t))
{
    beat_callback = b_cb;
}

void timer_clear_beat_callback(void)
{
    timer_set_beat_callback(NULL);
} 

int timer_set_bpm(void)
{
    uint32_t val = 0;
    uint32_t psc = 1;
    uint32_t err = 0;
    uint32_t reg = 0;
    uint32_t clock = (cpu_freq / (4 * Settings.bpm)) * (S_PER_MINUTE);;

    while (psc < 65535) {
        val = clock / psc;
        err = clock % psc;
        if ((val < 65535) && (err < (psc / 2))) {
            val--;
            break;
        }
        val = 0;
        psc++;
    }
    if (val == 0)
        return -1;
    TIM4_CR1    = 0;
    __asm__ volatile ("dmb");
    TIM4_PSC    = psc;
    TIM4_ARR    = val;
    TIM4_CNT    = val - 1;
    return 0;
}

int timer_start(void)
{
    TIM4_CR1    |= TIM_CR1_CLOCK_ENABLE;
    TIM4_DIER   |= TIM_DIER_UIE;
}

int timer_stop(void)
{
    TIM4_CR1    &= ~TIM_CR1_CLOCK_ENABLE;
    TIM4_DIER   &= ~TIM_DIER_UIE;
}

static void timer_irq_setup(void)
{
    nvic_irq_enable(NVIC_TIM4_IRQN);
    nvic_irq_setprio(NVIC_TIM4_IRQN, 0);
    APB1_CLOCK_RST |= TIM4_APB1_CLOCK_ER_VAL;
    __asm__ volatile ("dmb");
    APB1_CLOCK_RST &= ~TIM4_APB1_CLOCK_ER_VAL;
    APB1_CLOCK_ER |= TIM4_APB1_CLOCK_ER_VAL;
}


int timer_init(void)
{
    timer_stop();
    timer_irq_setup();
    timer_set_bpm();
    return 0;
}

static volatile uint32_t tim4_ticks = 0;
static volatile int pending_cb = 0;
void isr_tim1(void)
{
    TIM1_SR &= ~TIM_SR_UIF;
}

void isr_tim3(void)
{
    TIM3_SR &= ~TIM_SR_UIF;
}

static int beat = 1;
int timer_get_beat(void)
{
    return beat;
}

void timer_set_beat(int b)
{
    beat = b;
}

void timer_poll(void)
{
    if (beat_callback && (pending_cb > 0)) {
        pending_cb--;
        beat_callback(beat);
        beat++;
    }
}

void isr_tim4(void)
{
    TIM4_SR &= ~TIM_SR_UIF;
    tim4_ticks++;
    if (beat_callback) {
        pending_cb++;
    } else {
        led_beat((beat % 8) + 1);
    }
}