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samples: basic: fade_led: use pwm_dt_spec

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Simplify sample by using pwm_dt_spec.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
This commit is contained in:
Gerard Marull-Paretas 2022-04-04 20:43:35 +02:00 committed by Carles Cufí
parent 627f9e9ec8
commit f60bb8741b
2 changed files with 15 additions and 32 deletions
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4
samples/basic/fade_led/README.rst
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@ -10,7 +10,9 @@ This application "fades" a LED using the :ref:`PWM API <pwm_api>`.
The LED starts off increases its brightness until it is fully or nearly fully
on. The brightness then decreases until the LED is off, completing on fade
cycle. Each cycle takes 2.5 seconds, and the cycles repeat forever.
cycle. Each cycle takes 2.5 seconds, and the cycles repeat forever. The PWM
period is taken from Devicetree. It should be fast enough to be above the
flicker fusion threshold.
Requirements and Wiring
***********************

43
samples/basic/fade_led/src/main.c
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@ -14,63 +14,44 @@
#include <device.h>
#include <drivers/pwm.h>
#define PWM_LED0_NODE DT_ALIAS(pwm_led0)
static const struct pwm_dt_spec pwm_led0 = PWM_DT_SPEC_GET(DT_ALIAS(pwm_led0));
#if DT_NODE_HAS_STATUS(PWM_LED0_NODE, okay)
#define PWM_CTLR DT_PWMS_CTLR(PWM_LED0_NODE)
#define PWM_CHANNEL DT_PWMS_CHANNEL(PWM_LED0_NODE)
#define PWM_FLAGS DT_PWMS_FLAGS(PWM_LED0_NODE)
#else
#error "Unsupported board: pwm-led0 devicetree alias is not defined"
#define PWM_CTLR DT_INVALID_NODE
#define PWM_CHANNEL 0
#define PWM_FLAGS 0
#endif
/*
* This period should be fast enough to be above the flicker fusion
* threshold. The steps should also be small enough, and happen
* quickly enough, to make the output fade change appear continuous.
*/
#define PERIOD_USEC 20000U
#define NUM_STEPS 50U
#define STEP_USEC (PERIOD_USEC / NUM_STEPS)
#define SLEEP_MSEC 25U
void main(void)
{
const struct device *pwm;
uint32_t pulse_width = 0U;
uint32_t step = pwm_led0.period / NUM_STEPS;
uint8_t dir = 1U;
int ret;
printk("PWM-based LED fade\n");
pwm = DEVICE_DT_GET(PWM_CTLR);
if (!device_is_ready(pwm)) {
printk("Error: PWM device %s is not ready\n", pwm->name);
if (!device_is_ready(pwm_led0.dev)) {
printk("Error: PWM device %s is not ready\n",
pwm_led0.dev->name);
return;
}
while (1) {
ret = pwm_set_usec(pwm, PWM_CHANNEL, PERIOD_USEC, pulse_width,
PWM_FLAGS);
ret = pwm_set_nsec_pulse_dt(&pwm_led0, pulse_width);
if (ret) {
printk("Error %d: failed to set pulse width\n", ret);
return;
}
if (dir) {
pulse_width += STEP_USEC;
if (pulse_width >= PERIOD_USEC) {
pulse_width = PERIOD_USEC - STEP_USEC;
pulse_width += step;
if (pulse_width >= pwm_led0.period) {
pulse_width = pwm_led0.period - step;
dir = 0U;
}
} else {
if (pulse_width >= STEP_USEC) {
pulse_width -= STEP_USEC;
if (pulse_width >= step) {
pulse_width -= step;
} else {
pulse_width = STEP_USEC;
pulse_width = step;
dir = 1U;
}
}