led.cpp

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 *
 *   Copyright (C) 2015 PX4 Development Team. All rights reserved.
 *   Author: David Sidrane<david_s5@nscdg.com>
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#include <nuttx/config.h>

#include <stdint.h>

#include <arch/board/board.h>
#include "hardware/stm32_tim.h"


#include "led.hpp"

void rgb_led(int r, int g, int b, int freqs)
{

    long fosc = 72000000;
    long prescale = 2048;
    long p1s = fosc / prescale;
    long p0p5s  = p1s / 2;
    stm32_tim_channel_t mode = (stm32_tim_channel_t)(STM32_TIM_CH_OUTPWM | STM32_TIM_CH_POLARITY_NEG);
    static struct stm32_tim_dev_s *tim = 0;

    if (tim == 0) {
        tim = stm32_tim_init(3);
        STM32_TIM_SETMODE(tim, STM32_TIM_MODE_UP);
        STM32_TIM_SETCLOCK(tim, p1s - 8);
        STM32_TIM_SETPERIOD(tim, p1s);
        STM32_TIM_SETCOMPARE(tim, 1, 0);
        STM32_TIM_SETCOMPARE(tim, 2, 0);
        STM32_TIM_SETCOMPARE(tim, 3, 0);
        STM32_TIM_SETCHANNEL(tim, 1, mode);
        STM32_TIM_SETCHANNEL(tim, 2, mode);
        STM32_TIM_SETCHANNEL(tim, 3, mode);
    }

    long p  = freqs == 0 ? p1s : p1s / freqs;
    STM32_TIM_SETPERIOD(tim, p);

    p  = freqs == 0 ? p1s + 1 : p0p5s / freqs;

    STM32_TIM_SETCOMPARE(tim, 1, (r * p) / 255);
    STM32_TIM_SETCOMPARE(tim, 2, (g * p) / 255);
    STM32_TIM_SETCOMPARE(tim, 3, (b * p) / 255);
}