pwm.c
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/*
* Copyright (C) 2014-2016 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 cpu_lpc2387
* @ingroup drivers_periph_pwm
* @{
*
* @file
* @brief CPU specific low-level PWM driver implementation for the LPC2387
*
* The current implementation is somewhat limited: it supports only a single
* hardware PWM device (fixed to PWM1) and it is fixed on supporting 3 channels.
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "assert.h"
#include "bitarithm.h"
#include "periph/pwm.h"
/* guard file in case no PWM device is defined */
#ifdef PWM_NUMOF
/**
* @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)
{
if ((dev != PWM_DEV(0)) && (mode != PWM_LEFT)) {
return 0;
}
/* select function PWM[3] for pins */
PWM_PORT &= ~((3 << PWM_CH0_PIN * 2) |
(3 << PWM_CH1_PIN * 2) |
(3 << PWM_CH2_PIN * 2));
PWM_PORT |= (PWM_FUNC << PWM_CH0_PIN * 2) |
(PWM_FUNC << PWM_CH1_PIN * 2) |
(PWM_FUNC << PWM_CH2_PIN * 2);
/* power on PWM1 */
PCONP |= PCPWM1;
/* 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_CH0_MR = 0;
PWM_CH1_MR = 0;
PWM_CH2_MR = 0;
/* reset timer counter on MR0 match */
PWM1MCR = BIT1;
/* enable PWM1 channel 3, 4 and 5 */
PWM1PCR = (1 << (8 + PWM_CH0)) | (1 << (8 + PWM_CH1)) | (1 << (8 + PWM_CH2));
/* enable PWM1 timer in PWM mode */
PWM1TCR = BIT0 + BIT3;
/* update match registers */
PWM1LER = BIT0 | (1 << PWM_CH0) | (1 << PWM_CH1) | (1 << PWM_CH2);
return freq;
}
uint8_t pwm_channels(pwm_t dev)
{
assert(dev == PWM_DEV(0));
return PWM_CHANNELS;
}
void pwm_set(pwm_t dev, uint8_t channel, uint16_t value)
{
assert((dev == PWM_DEV(0)) && (channel < 3));
switch (channel) {
case 0:
PWM_CH0_MR = value;
PWM1LER |= (1 << PWM_CH0);
break;
case 1:
PWM_CH1_MR = value;
PWM1LER |= (1 << PWM_CH1);
break;
case 2:
PWM_CH2_MR = value;
PWM1LER |= (1 << PWM_CH2);
break;
}
}
void pwm_poweron(pwm_t dev)
{
assert(dev == PWM_DEV(0));
PCONP |= PCPWM1;
PWM1TCR |= BIT0;
}
void pwm_poweroff(pwm_t dev)
{
assert(dev == PWM_DEV(0));
PWM1TCR &= ~(BIT0);
PCONP &= ~(PCPWM1);
}
#endif /* PWM_NUMOF */