mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-05-25 00:44:10 +02:00
Kevin Thomas
85 lines
3.0 KiB
C
85 lines
3.0 KiB
C
/**
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* @file 0x04_pwm.c
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* @brief PWM demonstration: LED breathing effect via duty-cycle sweep
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* @author Kevin Thomas
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* @date 2025
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*
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* MIT License
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*
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* Copyright (c) 2025 Kevin Thomas
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* -----------------------------------------------------------------------------
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*
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* Demonstrates PWM output using the pwm driver (pwm.h / pwm.c). A 1 kHz
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* signal on GPIO 25 (onboard LED) sweeps its duty cycle from 0% to 100%
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* and back to produce a smooth breathing effect. The current duty is
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* reported over UART at 115200 baud.
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*
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* Wiring:
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* GPIO0 -> UART TX (USB-to-UART adapter RX)
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* GPIO1 -> UART RX (USB-to-UART adapter TX)
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* GPIO25 -> Onboard LED (no external wiring needed)
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*/
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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "pwm.h"
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#define PWM_PIN 25
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#define PWM_FREQ_HZ 1000
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/**
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* @brief Sweep the PWM duty cycle between start and end in given steps
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*
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* Iterates from start to end with the given step increment, updating
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* the PWM duty cycle and printing each value with a 50 ms delay.
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*
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* @param start Starting duty percentage
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* @param end Ending duty percentage
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* @param step Increment per iteration (negative for descending)
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*/
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static void _sweep_duty(int start, int end, int step) {
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for (int duty = start; (step > 0) ? duty <= end : duty >= end; duty += step) {
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pwm_driver_set_duty_percent((uint8_t)duty);
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printf("Duty: %3d%%\r\n", duty);
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sleep_ms(50);
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}
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}
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/**
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* @brief Application entry point for the PWM LED breathing demo
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*
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* Initializes PWM at 1 kHz on the onboard LED and enters an infinite
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* loop that sweeps the duty cycle up and down to produce a smooth
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* breathing effect, reporting each step over UART.
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*
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* @return int Does not return
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*/
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int main(void) {
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stdio_init_all();
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pwm_driver_init(PWM_PIN, PWM_FREQ_HZ);
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printf("PWM initialized: GPIO%d @ %d Hz\r\n", PWM_PIN, PWM_FREQ_HZ);
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while (true) {
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_sweep_duty(0, 100, 5);
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_sweep_duty(100, 0, -5);
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}
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}
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