mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
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80 lines
2.6 KiB
C
80 lines
2.6 KiB
C
/**
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* @file dht11.c
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* @brief Implementation of DHT11 temperature and humidity sensor driver
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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 "dht11.h"
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#include "hardware/gpio.h"
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#include "pico/time.h"
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static uint dht_pin;
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void dht11_init(uint8_t pin) {
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dht_pin = pin;
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gpio_init(pin);
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gpio_pull_up(pin);
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}
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bool dht11_read(float *humidity, float *temperature) {
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uint8_t data[5] = {0};
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// Start signal
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gpio_set_dir(dht_pin, GPIO_OUT);
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gpio_put(dht_pin, 0);
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sleep_ms(18);
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gpio_put(dht_pin, 1);
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sleep_us(40);
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gpio_set_dir(dht_pin, GPIO_IN);
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// Wait for response
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uint32_t timeout = 10000;
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while (gpio_get(dht_pin) == 1) if (--timeout == 0) return false;
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timeout = 10000;
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while (gpio_get(dht_pin) == 0) if (--timeout == 0) return false;
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timeout = 10000;
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while (gpio_get(dht_pin) == 1) if (--timeout == 0) return false;
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// Read 40 bits
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for (int i = 0; i < 40; i++) {
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timeout = 10000;
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while (gpio_get(dht_pin) == 0) if (--timeout == 0) return false;
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uint32_t start = time_us_32();
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timeout = 10000;
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while (gpio_get(dht_pin) == 1) if (--timeout == 0) return false;
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uint32_t duration = time_us_32() - start;
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data[i / 8] <<= 1;
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if (duration > 40) data[i / 8] |= 1;
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}
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// Check checksum
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if (data[4] != ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) return false;
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*humidity = data[0] + data[1] * 0.1f;
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*temperature = data[2] + data[3] * 0.1f;
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return true;
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}
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