187a8ad09b
Some boards may define LEDs but disable them by default due to conflicts
with other peripherals. In this case, the new sample code introduced in
a5fd92b ("samples: fade_led: use all available LEDs") fails to build
with a missing symbol error.
Fix this by checking if the PWM device (the parent of the LED alias) is
enabled before using it. This implicitly discards invalid aliases.
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>
75 lines
1.8 KiB
C
75 lines
1.8 KiB
C
/*
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* Copyright (c) 2016 Intel Corporation
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* Copyright (c) 2020 Nordic Semiconductor ASA
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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-based LED fade
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*/
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#include <zephyr/kernel.h>
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#include <zephyr/sys/printk.h>
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#include <zephyr/device.h>
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#include <zephyr/drivers/pwm.h>
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#define PWM_LED_ALIAS(i) DT_ALIAS(_CONCAT(pwm_led, i))
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#define PWM_LED_IS_OKAY(i) DT_NODE_HAS_STATUS_OKAY(DT_PARENT(PWM_LED_ALIAS(i)))
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#define PWM_LED(i, _) IF_ENABLED(PWM_LED_IS_OKAY(i), (PWM_DT_SPEC_GET(PWM_LED_ALIAS(i)),))
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#define MAX_LEDS 10
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static const struct pwm_dt_spec pwm_leds[] = {LISTIFY(MAX_LEDS, PWM_LED, ())};
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#define NUM_STEPS 50U
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#define SLEEP_MSEC 25U
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int main(void)
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{
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uint32_t pulse_widths[ARRAY_SIZE(pwm_leds)];
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uint32_t steps[ARRAY_SIZE(pwm_leds)];
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uint8_t dir = 1U;
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int ret;
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printk("PWM-based LED fade. Found %d LEDs\n", ARRAY_SIZE(pwm_leds));
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for (size_t i = 0; i < ARRAY_SIZE(pwm_leds); i++) {
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pulse_widths[i] = 0;
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steps[i] = pwm_leds[i].period / NUM_STEPS;
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if (!pwm_is_ready_dt(&pwm_leds[i])) {
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printk("Error: PWM device %s is not ready\n", pwm_leds[i].dev->name);
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return 0;
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}
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}
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while (1) {
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for (size_t i = 0; i < ARRAY_SIZE(pwm_leds); i++) {
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ret = pwm_set_pulse_dt(&pwm_leds[i], pulse_widths[i]);
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if (ret) {
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printk("Error %d: failed to set pulse width for LED %d\n", ret, i);
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}
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printk("LED %d: Using pulse width %d%%\n", i,
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100 * pulse_widths[i] / pwm_leds[i].period);
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if (dir) {
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if (pulse_widths[i] + steps[i] >= pwm_leds[i].period) {
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pulse_widths[i] = pwm_leds[i].period;
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dir = 0U;
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} else {
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pulse_widths[i] += steps[i];
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}
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} else {
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if (pulse_widths[i] <= steps[i]) {
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pulse_widths[i] = 0;
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dir = 1U;
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} else {
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pulse_widths[i] -= steps[i];
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}
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}
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}
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k_sleep(K_MSEC(SLEEP_MSEC));
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}
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return 0;
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}
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