rt-thread/bsp/apollo2/board/pwm.c

/*
 * File      :_pwm.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2006 - 2017, RT-Thread Development Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Change Logs:
 * Date           Author       Notes
 * 2017-12-04     Haley        the first version
 */

#include <rtthread.h>
#include <rtdevice.h>
#include "am_mcu_apollo.h"
#include "board.h"

#ifdef RT_USING_PWM

// LED3 is pin 19
#define AM_BSP_GPIO_PWM_LED                 19
#define AM_BSP_GPIO_CFG_PWM_LED             AM_HAL_PIN_19_TCTB1

#define AM_BSP_PWM_LED_TIMER                1
#define AM_BSP_PWM_LED_TIMER_SEG            AM_HAL_CTIMER_TIMERB
#define AM_BSP_PWM_LED_TIMER_INT            AM_HAL_CTIMER_INT_TIMERB1

/**
 * @brief LED brightness profile
 *
 * This function define LED brightness profile
 *
 * @return None.
 */
volatile uint32_t g_ui32Index = 0;
const uint32_t g_pui32Brightness[64] =
{
    1, 1, 1, 2, 3, 4, 6, 8,
    10, 12, 14, 17, 20, 23, 25, 28,
    31, 35, 38, 40, 43, 46, 49, 51,
    53, 55, 57, 59, 60, 61, 62, 62,
    63, 62, 62, 61, 60, 59, 57, 55,
    53, 51, 49, 46, 43, 40, 38, 35,
    32, 28, 25, 23, 20, 17, 14, 12,
    10, 8, 6, 4, 3, 2, 1, 1
};

/**
 * @brief Interrupt handler for the Timer
 *
 * This function is Interrupt handler for the Timer
 *
 * @return None.
 */
void am_ctimer_isr(void)
{
    /* Clear the interrupt that got us here */
    am_hal_ctimer_int_clear(AM_BSP_PWM_LED_TIMER_INT);

    /* Now set new PWM half-period for the LED */
    am_hal_ctimer_period_set(AM_BSP_PWM_LED_TIMER, AM_BSP_PWM_LED_TIMER_SEG,
                             64, g_pui32Brightness[g_ui32Index]);

    /* Set up the LED duty cycle for the next pulse */
    g_ui32Index = (g_ui32Index + 1) % 64;
}

/**
 * @brief Initialize the PWM
 *
 * This function initialize the PWM
 *
 * @return 0.
 */
int rt_hw_pwm_init(void)
{
    /* init pwm gpio */
    am_hal_gpio_pin_config(AM_BSP_GPIO_PWM_LED, AM_BSP_GPIO_CFG_PWM_LED);

    /* Configure a timer to drive the LED */
    am_hal_ctimer_config_single(AM_BSP_PWM_LED_TIMER, AM_BSP_PWM_LED_TIMER_SEG,
                                (AM_HAL_CTIMER_FN_PWM_REPEAT |
                                 AM_HAL_CTIMER_XT_2_048KHZ |
                                 AM_HAL_CTIMER_INT_ENABLE |
                                 AM_HAL_CTIMER_PIN_ENABLE));

    /* Set up initial timer period */
    am_hal_ctimer_period_set(AM_BSP_PWM_LED_TIMER, AM_BSP_PWM_LED_TIMER_SEG,
                             64, 32);

    /* Enable interrupts for the Timer we are using on this board */
    am_hal_ctimer_int_enable(AM_BSP_PWM_LED_TIMER_INT);
    am_hal_interrupt_enable(AM_HAL_INTERRUPT_CTIMER);

    /* Start the timer */
    am_hal_ctimer_start(AM_BSP_PWM_LED_TIMER, AM_BSP_PWM_LED_TIMER_SEG);

    rt_kprintf("pwm_init!\n");

    return 0;
}
#ifdef RT_USING_COMPONENTS_INIT
INIT_BOARD_EXPORT(rt_hw_pwm_init);
#endif

#endif

/*@}*/