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https://github.com/mytechnotalent/Embedded-Hacking.git
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81 lines
2.7 KiB
C
81 lines
2.7 KiB
C
/**
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* @file ir.c
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* @brief Implementation of NEC IR receiver (decoder)
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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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#include "ir.h"
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#include "pico/stdlib.h"
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#include "pico/time.h"
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#include "hardware/gpio.h"
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static unsigned int ir_pin = 0;
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// Wait for 'gpio' to reach 'level' or timeout (microseconds). Return elapsed us or -1.
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static int64_t wait_for_level(unsigned int gpio, bool level, uint32_t timeout_us) {
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absolute_time_t start = get_absolute_time();
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while (gpio_get(gpio) != level) {
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if (absolute_time_diff_us(start, get_absolute_time()) > (int64_t)timeout_us) {
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return -1;
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}
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}
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return absolute_time_diff_us(start, get_absolute_time());
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}
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void ir_init(uint8_t pin) {
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ir_pin = pin;
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gpio_init(pin);
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gpio_set_dir(pin, GPIO_IN);
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gpio_pull_up(pin);
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}
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int ir_getkey(void) {
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// leader low (~9 ms)
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if (wait_for_level(ir_pin, 0, 150000) < 0) return -1;
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int64_t t = wait_for_level(ir_pin, 1, 12000);
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if (t < 8000 || t > 10000) return -1;
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t = wait_for_level(ir_pin, 0, 7000);
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if (t < 3500 || t > 5000) return -1;
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uint8_t data[4] = {0, 0, 0, 0};
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for (int i = 0; i < 32; ++i) {
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if (wait_for_level(ir_pin, 1, 1000) < 0) return -1;
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t = wait_for_level(ir_pin, 0, 2500);
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if (t < 200) return -1;
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int byte_idx = i / 8;
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int bit_idx = i % 8;
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if (t > 1200) data[byte_idx] |= (1 << bit_idx); // logical '1'
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}
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// Validate address/data inverted pairs
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if ((uint8_t)(data[0] + data[1]) == 0xFF && (uint8_t)(data[2] + data[3]) == 0xFF) {
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return data[2];
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}
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return -1;
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}
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