| /* |
| * Copyright (c) 2016 Intel Corporation |
| * Copyright (c) 2020 Nordic Semiconductor ASA |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| /** |
| * @file Sample app to demonstrate PWM-based LED fade |
| */ |
| |
| #include <zephyr.h> |
| #include <sys/printk.h> |
| #include <device.h> |
| #include <drivers/pwm.h> |
| |
| #define PWM_LED0_NODE 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; |
| 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); |
| return; |
| } |
| |
| while (1) { |
| ret = pwm_pin_set_usec(pwm, PWM_CHANNEL, PERIOD_USEC, |
| pulse_width, PWM_FLAGS); |
| 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; |
| dir = 0U; |
| } |
| } else { |
| if (pulse_width >= STEP_USEC) { |
| pulse_width -= STEP_USEC; |
| } else { |
| pulse_width = STEP_USEC; |
| dir = 1U; |
| } |
| } |
| |
| k_sleep(K_MSEC(SLEEP_MSEC)); |
| } |
| } |