RIOT/cpu/lpc2387/periph/pwm.c

/*
 * Copyright (C) 2014 Freie Universität Berlin
 *
 * This file is subject to the terms and conditions of the GNU Lesser General
 * Public License v2.1. See the file LICENSE in the top level directory for more
 * details.
 */

/**
 * @ingroup     lpc2387
 * @{
 *
 * @file
 * @brief       CPU specific low-level PWM driver implementation for the LPC2387
 *
 * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
 *
 * @}
 */

#include "bitarithm.h"
#include "lpc2387.h"
#include "periph_conf.h"

/* guard file in case no PWM device is defined */
#if (PWM_0_EN || PWM_1_EN)

/* pull the PWM header inside the guards for now. Guards will be removed on
 * adapting this driver implementation... */
#include "periph/pwm.h"

/**
 * @note The PWM is always initialized with left-aligned mode.
 *
 * TODO: add center and right aligned modes
 */
uint32_t pwm_init(pwm_t dev, pwm_mode_t mode, uint32_t freq, uint16_t res)
{
    (void) mode; /* unused */

    switch (dev) {
#if PWM_0_EN
        case PWM_0:
            /* select function PWM[3] for pins */
            PWM_0_PORT &= ~((3 << PWM_0_CH0_PIN * 2) |
                            (3 << PWM_0_CH1_PIN * 2) |
                            (3 << PWM_0_CH2_PIN * 2));
            PWM_0_PORT |= (PWM_0_FUNC << PWM_0_CH0_PIN * 2) |
                          (PWM_0_FUNC << PWM_0_CH1_PIN * 2) |
                          (PWM_0_FUNC << PWM_0_CH2_PIN * 2);

            /* power on PWM1 */
            pwm_poweron(dev);

            /* select PWM1 clock */
            PCLKSEL0 &= ~(BIT13);
            PCLKSEL0 |= (BIT12);

            /* reset PWM1s counter */
            PWM1TCR = BIT1;

            /* set prescaler */
            PWM1PR = (CLOCK_CORECLOCK / (freq * res)) - 1;

            /* set match register */
            PWM1MR0 = res;
            PWM_0_CH0_MR = 0;
            PWM_0_CH1_MR = 0;
            PWM_0_CH2_MR = 0;

            /* reset timer counter on MR0 match */
            PWM1MCR = BIT1;

            /* enable PWM1 channel 3, 4 and 5 */
            PWM1PCR = (1 << (8 + PWM_0_CH0)) | (1 << (8 + PWM_0_CH1)) | (1 << (8 + PWM_0_CH2));

            /* enable PWM1 timer in PWM mode */
            PWM1TCR = BIT0 + BIT3;

            /* update match registers */
            PWM1LER = BIT0 | (1 << PWM_0_CH0) | (1 << PWM_0_CH1) | (1 << PWM_0_CH2);
            break;
#endif
        default:
            return 0;
    }

    return freq;
}

uint8_t pwm_channels(pwm_t dev)
{
    if (dev == PWM_0) {
        return PWM_0_CHANNELS;
    }
    return 0;
}

void pwm_set(pwm_t dev, uint8_t channel, uint16_t value)
{
    switch (dev) {
#if PWM_0_EN
        case PWM_0:
            switch (channel) {
                case 0:
                    PWM_0_CH0_MR = value;
                    PWM1LER |= (1 << PWM_0_CH0);
                    break;
                case 1:
                    PWM_0_CH1_MR = value;
                    PWM1LER |= (1 << PWM_0_CH1);
                    break;
                case 2:
                    PWM_0_CH2_MR = value;
                    PWM1LER |= (1 << PWM_0_CH2);
                    break;
                default:
                    return;
                    break;
            }
            break;
#endif
    }
}

void pwm_start(pwm_t dev)
{
    switch (dev) {
#if PWM_0_EN
        case PWM_0:
            PWM1TCR |= BIT0;
            break;
#endif
    }
}

void pwm_stop(pwm_t dev)
{
    switch (dev) {
#if PWM_0_EN
        case PWM_0:
            PWM1TCR &= ~(BIT0);
            break;
#endif
    }
}

void pwm_poweron(pwm_t dev)
{
    switch (dev) {
#if PWM_0_EN
        case PWM_0:
            PCONP |= PCPWM1;
            break;
#endif
    }
}

void pwm_poweroff(pwm_t dev)
{
    switch (dev) {
#if PWM_0_EN
        case PWM_0:
            PCONP &= ~(PCPWM1);
            break;
#endif
    }
}

#endif /* (PWM_0_EN || PWM_1_EN) */