mirror of
https://github.com/RobTillaart/Arduino.git
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156 lines
3.6 KiB
C++
156 lines
3.6 KiB
C++
//
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// FILE: DHT2pin.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.1
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// PURPOSE: Experimental DHT Temperature & Humidity Sensor library for Arduino
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// URL: https://github.com/RobTillaart/DHT2pin
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// http://arduino.cc/playground/Main/DHTLib
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//
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// HISTORY:
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// 0.1.1 2020-12-19 added arduino-ci + unit test
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// 0.1.0 2020-06-30 own repository; #pragma once
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// 0.0.3 Fix issue #33
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// 0.0.2 support for non "F_CPU" boards especially Galileo
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// Tested and verified by Maria Emanuella Moura Silva (thanks)
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// changed name to DHT2pin
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// 0.0.1 initial version - 2016 SEP 05 (based upon 0.1.13 DHT)
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//
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#include "DHT2pin.h"
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/////////////////////////////////////////////////////
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//
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// PUBLIC
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//
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_CHECKSUM
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// DHTLIB_ERROR_TIMEOUT
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int DHT2pin::read11()
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{
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// READ VALUES
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int rv = _readSensor(DHTLIB_DHT11_WAKEUP);
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if (rv != DHTLIB_OK)
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{
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humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?
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temperature = DHTLIB_INVALID_VALUE; // invalid value
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return rv;
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}
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// CONVERT AND STORE
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humidity = bits[0]; // bits[1] == 0;
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temperature = bits[2]; // bits[3] == 0;
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// TEST CHECKSUM
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// bits[1] && bits[3] both 0
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uint8_t sum = bits[0] + bits[2];
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if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM;
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return DHTLIB_OK;
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}
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_CHECKSUM
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// DHTLIB_ERROR_TIMEOUT
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int DHT2pin::read()
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{
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// READ VALUES
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int rv = _readSensor(DHTLIB_DHT_WAKEUP);
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if (rv != DHTLIB_OK)
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{
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humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?
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temperature = DHTLIB_INVALID_VALUE; // invalid value
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return rv; // propagate error value
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}
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// CONVERT AND STORE
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humidity = word(bits[0], bits[1]) * 0.1;
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temperature = word(bits[2] & 0x7F, bits[3]) * 0.1;
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if (bits[2] & 0x80) // negative temperature
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{
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temperature = -temperature;
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}
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// TEST CHECKSUM
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uint8_t sum = bits[0] + bits[1] + bits[2] + bits[3];
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if (bits[4] != sum)
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{
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return DHTLIB_ERROR_CHECKSUM;
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}
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return DHTLIB_OK;
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}
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/////////////////////////////////////////////////////
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//
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// PRIVATE
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//
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_TIMEOUT
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int DHT2pin::_readSensor(uint8_t wakeupDelay)
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{
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// INIT BUFFERVAR TO RECEIVE DATA
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uint8_t mask = 128;
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uint8_t idx = 0;
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// EMPTY BUFFER
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for (uint8_t i = 0; i < 5; i++) bits[i] = 0;
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// REQUEST SAMPLE
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digitalWrite(_wpin, LOW);
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delay(wakeupDelay);
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digitalWrite(_wpin, HIGH);
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delayMicroseconds(40);
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// GET ACKNOWLEDGE or TIMEOUT
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uint16_t loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_rpin) == LOW)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_rpin) == HIGH)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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// READ THE OUTPUT - 40 BITS => 5 BYTES
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for (uint8_t i = 40; i != 0; i--)
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{
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loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_rpin) == LOW)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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uint32_t t = micros();
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loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_rpin) == HIGH)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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if ((micros() - t) > 40)
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{
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bits[idx] |= mask;
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}
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mask >>= 1;
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if (mask == 0) // next byte?
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{
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mask = 128;
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idx++;
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}
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}
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digitalWrite(_wpin, HIGH);
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return DHTLIB_OK;
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}
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//
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// END OF FILE
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//
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