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303 lines
8.6 KiB
303 lines
8.6 KiB
// -----------------------------------------------------------------------------
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// DHTXX Sensor
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// Copyright (C) 2017-2019 by Xose Pérez <xose dot perez at gmail dot com>
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// -----------------------------------------------------------------------------
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#if SENSOR_SUPPORT && DHT_SUPPORT
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#pragma once
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#include <Arduino.h>
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#include "../gpio.h"
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#include "../utils.h"
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#include "BaseSensor.h"
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constexpr const double DHT_DUMMY_VALUE = -255;
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constexpr const size_t DHT_MAX_DATA = 5;
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constexpr const size_t DHT_MAX_ERRORS = 5;
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constexpr const uint32_t DHT_MIN_INTERVAL = 2000;
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enum class DHTChipType {
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DHT11,
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DHT12,
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DHT21,
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DHT22,
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AM2301,
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SI7021
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};
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// Note: backwards compatibility for configuration headers
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#define DHT_CHIP_DHT11 DHTChipType::DHT11
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#define DHT_CHIP_DHT12 DHTChipType::DHT12
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#define DHT_CHIP_DHT22 DHTChipType::DHT22
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#define DHT_CHIP_DHT21 DHTChipType::DHT21
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#define DHT_CHIP_AM2301 DHTChipType::AM2301
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#define DHT_CHIP_SI7021 DHTChipType::SI7021
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int dhtchip_to_number(DHTChipType chip) {
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switch (chip) {
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case DHTChipType::DHT11:
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return 11;
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case DHTChipType::DHT12:
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return 12;
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case DHTChipType::DHT21:
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case DHTChipType::AM2301:
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return 21;
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case DHTChipType::DHT22:
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case DHTChipType::SI7021:
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return 22;
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default:
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return -1;
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}
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}
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class DHTSensor : public BaseSensor {
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public:
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// ---------------------------------------------------------------------
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// Public
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// ---------------------------------------------------------------------
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DHTSensor() {
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_count = 2;
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_sensor_id = SENSOR_DHTXX_ID;
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}
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~DHTSensor() {
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gpioUnlock(_gpio);
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}
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// ---------------------------------------------------------------------
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void setGPIO(unsigned char gpio) {
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_gpio = gpio;
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}
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void setType(DHTChipType type) {
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_type = type;
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}
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// ---------------------------------------------------------------------
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unsigned char getGPIO() {
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return _gpio;
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}
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int getType() {
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return dhtchip_to_number(_type);
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}
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DHTChipType getChipType() {
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return _type;
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}
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// ---------------------------------------------------------------------
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// Sensor API
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// ---------------------------------------------------------------------
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// Initialization method, must be idempotent
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void begin() {
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_count = 0;
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// Manage GPIO lock (note that this only handles the basic *hw* I/O)
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if (_previous != GPIO_NONE) {
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gpioUnlock(_previous);
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}
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_previous = GPIO_NONE;
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if (!gpioLock(_gpio)) {
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_error = SENSOR_ERROR_GPIO_USED;
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return;
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}
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_previous = _gpio;
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// Set now to fail the check in _read at least once
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_last_ok = millis();
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_count = 2;
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_ready = true;
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}
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// Pre-read hook (usually to populate registers with up-to-date data)
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void pre() {
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_error = SENSOR_ERROR_OK;
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_read();
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}
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// Descriptive name of the sensor
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String description() {
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char buffer[20];
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snprintf(buffer, sizeof(buffer), "DHT%d @ GPIO%d", dhtchip_to_number(_type), _gpio);
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return String(buffer);
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}
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// Descriptive name of the slot # index
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String description(unsigned char index) {
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return description();
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};
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// Address of the sensor (it could be the GPIO or I2C address)
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String address(unsigned char index) {
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return String(_gpio);
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}
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// Type for slot # index
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unsigned char type(unsigned char index) {
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if (index == 0) return MAGNITUDE_TEMPERATURE;
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if (index == 1) return MAGNITUDE_HUMIDITY;
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return MAGNITUDE_NONE;
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}
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// Current value for slot # index
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double value(unsigned char index) {
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if (index == 0) return _temperature;
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if (index == 1) return _humidity;
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return 0;
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}
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protected:
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// ---------------------------------------------------------------------
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// Protected
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// ---------------------------------------------------------------------
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void _read() {
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if ((_last_ok > 0) && (millis() - _last_ok < DHT_MIN_INTERVAL)) {
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if ((_temperature == DHT_DUMMY_VALUE) && (_humidity == DHT_DUMMY_VALUE)) {
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_error = SENSOR_ERROR_WARM_UP;
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} else {
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_error = SENSOR_ERROR_OK;
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}
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return;
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}
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unsigned long low = 0;
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unsigned long high = 0;
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unsigned char dhtData[DHT_MAX_DATA] = {0};
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unsigned char byteInx = 0;
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unsigned char bitInx = 7;
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pinMode(_gpio, OUTPUT);
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// Send start signal to DHT sensor
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if (++_errors > DHT_MAX_ERRORS) {
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_errors = 0;
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digitalWrite(_gpio, HIGH);
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nice_delay(250);
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}
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noInterrupts();
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digitalWrite(_gpio, LOW);
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if ((_type == DHT_CHIP_DHT11) || (_type == DHT_CHIP_DHT12)) {
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nice_delay(20);
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} else if (_type == DHT_CHIP_SI7021) {
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delayMicroseconds(500);
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} else {
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delayMicroseconds(1100);
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}
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digitalWrite(_gpio, HIGH);
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delayMicroseconds(40);
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pinMode(_gpio, INPUT_PULLUP);
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delayMicroseconds(10);
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// No errors, read the 40 data bits
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for( int k = 0; k < 41; k++ ) {
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// Starts new data transmission with >50us low signal
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low = _signal(100, LOW);
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if (low == 0) {
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_error = SENSOR_ERROR_TIMEOUT;
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return;
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}
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// Check to see if after >70us rx data is a 0 or a 1
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high = _signal(100, HIGH);
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if (high == 0) {
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_error = SENSOR_ERROR_TIMEOUT;
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return;
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}
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// Skip the first bit
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if (k == 0) continue;
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// add the current read to the output data
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// since all dhtData array where set to 0 at the start,
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// only look for "1" (>28us us)
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if (high > low) dhtData[byteInx] |= (1 << bitInx);
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// index to next byte
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if (bitInx == 0) {
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bitInx = 7;
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++byteInx;
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} else {
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--bitInx;
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}
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}
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interrupts();
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// Verify checksum
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if (dhtData[4] != ((dhtData[0] + dhtData[1] + dhtData[2] + dhtData[3]) & 0xFF)) {
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_error = SENSOR_ERROR_CRC;
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return;
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}
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// Get humidity from Data[0] and Data[1]
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if (_type == DHT_CHIP_DHT11) {
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_humidity = dhtData[0];
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} else if (_type == DHT_CHIP_DHT12) {
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_humidity = dhtData[0];
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_humidity += dhtData[1] * 0.1;
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} else {
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_humidity = dhtData[0] * 256 + dhtData[1];
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_humidity /= 10;
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}
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// Get temp from Data[2] and Data[3]
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if (_type == DHT_CHIP_DHT11) {
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_temperature = dhtData[2];
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} else if (_type == DHT_CHIP_DHT12) {
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_temperature = (dhtData[2] & 0x7F);
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_temperature += dhtData[3] * 0.1;
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if (dhtData[2] & 0x80) _temperature *= -1;
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} else {
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_temperature = (dhtData[2] & 0x7F) * 256 + dhtData[3];
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_temperature /= 10;
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if (dhtData[2] & 0x80) _temperature *= -1;
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}
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_last_ok = millis();
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_errors = 0;
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_error = SENSOR_ERROR_OK;
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}
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unsigned long _signal(unsigned long usTimeOut, bool state) {
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unsigned long uSec = 1;
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while (digitalRead(_gpio) == state) {
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if (++uSec > usTimeOut) return 0;
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delayMicroseconds(1);
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}
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return uSec;
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}
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DHTChipType _type = DHT_CHIP_DHT22;
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unsigned char _gpio = GPIO_NONE;
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unsigned char _previous = GPIO_NONE;
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unsigned long _last_ok = 0;
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unsigned char _errors = 0;
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double _temperature = DHT_DUMMY_VALUE;
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double _humidity = DHT_DUMMY_VALUE;
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};
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#endif // SENSOR_SUPPORT && DHT_SUPPORT
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