db611e6781
Add support for requesting an inverted PWM pulse (active-low) when setting up the period and pulse width of a PWM pin. This is useful when driving external, active-low circuitry (e.g. an LED) with a PWM signal. All in-tree PWM drivers is updated to match the new API signature, but no driver support for inverted PWM signals is added yet. All in-tree PWM consumers are updated to pass a flags value of 0 (0 meaning default, which is normal PWM polarity). Fixes #21384. Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
72 lines
1.3 KiB
C
72 lines
1.3 KiB
C
/*
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* Copyright (c) 2016 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file Sample app to demonstrate PWM.
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*
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* This app uses PWM[0].
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*/
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#include <zephyr.h>
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#include <sys/printk.h>
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#include <device.h>
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#include <drivers/pwm.h>
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#ifndef DT_ALIAS_PWM_0_LABEL
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#error "Choose supported board or add new board for the application"
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#endif
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/*
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* Unlike pulse width, period is not a critical parameter for
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* motor control. 20ms is commonly used.
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*/
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#define PERIOD (USEC_PER_SEC / 50U)
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/* all in micro second */
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#define STEPSIZE 100
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#define MINPULSEWIDTH 700
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#define MAXPULSEWIDTH 2300
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void main(void)
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{
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struct device *pwm_dev;
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u32_t pulse_width = MINPULSEWIDTH;
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u8_t dir = 0U;
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printk("PWM demo app-servo control\n");
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pwm_dev = device_get_binding(DT_ALIAS_PWM_0_LABEL);
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if (!pwm_dev) {
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printk("Cannot find PWM device!\n");
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return;
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}
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while (1) {
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if (pwm_pin_set_usec(pwm_dev, 0, PERIOD, pulse_width, 0)) {
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printk("pwm pin set fails\n");
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return;
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}
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if (dir) {
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if (pulse_width <= MINPULSEWIDTH) {
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dir = 0U;
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pulse_width = MINPULSEWIDTH;
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} else {
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pulse_width -= STEPSIZE;
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}
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} else {
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pulse_width += STEPSIZE;
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if (pulse_width >= MAXPULSEWIDTH) {
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dir = 1U;
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pulse_width = MAXPULSEWIDTH;
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}
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}
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k_sleep(MSEC_PER_SEC);
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}
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}
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