mirror of
https://github.com/RobTillaart/Arduino.git
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266 lines
7.7 KiB
C++
266 lines
7.7 KiB
C++
//
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// FILE: dht.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.33
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// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino, AVR optimized
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// URL: https://github.com/RobTillaart/DHTlib
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// http://arduino.cc/playground/Main/DHTLib
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//
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// HISTORY:
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// 0.1.33 2021-02-16 fix #6 T-GO signal in handshake. (needed for long wires)
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// 0.1.32 2021-02-01 fix negative temperature DHT22 again (code from DHTNew)
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// 0.1.31 2020-12-15 fix negative temperature DHT22 (code from DHTNew)
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// 0.1.30 2020-06-30 own repo;
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// 0.1.29 2018-09-02 fix negative temperature DHT12 - issue #111
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// 0.1.28 2018-04-03 refactor
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// 0.1.27 2018-03-26 added _disableIRQ flag
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// 0.1.26 2017-12-12 explicit support for AM23XX series and DHT12
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// 0.1.25 2017-09-20 FIX https://github.com/RobTillaart/Arduino/issues/80
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// 0.1.24 2017-07-27 FIX https://github.com/RobTillaart/Arduino/issues/33 double -> float
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// 0.1.23 2017-07-24 FIX https://github.com/RobTillaart/Arduino/issues/31
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// 0.1.22 undo delayMicroseconds() for wakeups larger than 8
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// 0.1.21 replace delay with delayMicroseconds() + small fix
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// 0.1.20 Reduce footprint by using uint8_t as error codes. (thanks to chaveiro)
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// 0.1.19 masking error for DHT11 - FIXED (thanks Richard for noticing)
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// 0.1.18 version 1.16/17 broke the DHT11 - FIXED
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// 0.1.17 replaced micros() with adaptive loopcount
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// removed DHTLIB_INVALID_VALUE
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// added DHTLIB_ERROR_CONNECT
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// added DHTLIB_ERROR_ACK_L DHTLIB_ERROR_ACK_H
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// 0.1.16 masking unused bits (less errors); refactored bits[]
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// 0.1.15 reduced # micros calls 2->1 in inner loop.
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// 0.1.14 replace digital read with faster (~3x) code => more robust low MHz machines.
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//
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// 0.1.13 fix negative temperature
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// 0.1.12 support DHT33 and DHT44 initial version
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// 0.1.11 renamed DHTLIB_TIMEOUT
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// 0.1.10 optimized faster WAKEUP + TIMEOUT
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// 0.1.09 optimize size: timeout check + use of mask
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// 0.1.08 added formula for timeout based upon clockspeed
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// 0.1.07 added support for DHT21
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// 0.1.06 minimize footprint (2012-12-27)
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// 0.1.05 fixed negative temperature bug (thanks to Roseman)
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// 0.1.04 improved readability of code using DHTLIB_OK in code
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// 0.1.03 added error values for temp and humidity when read failed
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// 0.1.02 added error codes
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// 0.1.01 added support for Arduino 1.0, fixed typos (31/12/2011)
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// 0.1.00 by Rob Tillaart (01/04/2011)
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//
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// inspired by DHT11 library
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#include "dht.h"
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/////////////////////////////////////////////////////
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//
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// PUBLIC
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//
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int8_t dht::read11(uint8_t pin)
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{
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// READ VALUES
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if (_disableIRQ) noInterrupts();
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int8_t result = _readSensor(pin, DHTLIB_DHT11_WAKEUP, DHTLIB_DHT11_LEADING_ZEROS);
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if (_disableIRQ) interrupts();
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// these bits are always zero, masking them reduces errors.
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bits[0] &= 0x7F;
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bits[2] &= 0x7F;
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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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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 result;
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}
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int8_t dht::read12(uint8_t pin)
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{
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// READ VALUES
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if (_disableIRQ) noInterrupts();
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int8_t result = _readSensor(pin, DHTLIB_DHT11_WAKEUP, DHTLIB_DHT11_LEADING_ZEROS);
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if (_disableIRQ) interrupts();
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// CONVERT AND STORE
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humidity = bits[0] + bits[1] * 0.1;
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temperature = bits[2] + (bits[3] & 0x7F) * 0.1;
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if (bits[3] & 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 result;
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}
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int8_t dht::read(uint8_t pin)
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{
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// READ VALUES
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if (_disableIRQ) noInterrupts();
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int8_t result = _readSensor(pin, DHTLIB_DHT_WAKEUP, DHTLIB_DHT_LEADING_ZEROS);
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if (_disableIRQ) interrupts();
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// these bits are always zero, masking them reduces errors.
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bits[0] &= 0x03;
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bits[2] &= 0x83;
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// CONVERT AND STORE
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humidity = (bits[0] * 256 + bits[1]) * 0.1;
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int16_t t = (bits[2] * 256 + bits[3]);
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temperature = t * 0.1;
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// HEXDUMP DEBUG
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/*
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Serial.println();
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// CHECKSUM
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if (_bits[4] < 0x10) Serial.print(0);
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Serial.print(_bits[4], HEX);
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Serial.print(" ");
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// TEMPERATURE
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if (_bits[2] < 0x10) Serial.print(0);
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Serial.print(_bits[2], HEX);
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if (_bits[3] < 0x10) Serial.print(0);
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Serial.print(_bits[3], HEX);
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Serial.print(" ");
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Serial.print(temperature, 1);
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Serial.print(" ");
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// HUMIDITY
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if (_bits[0] < 0x10) Serial.print(0);
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Serial.print(_bits[0], HEX);
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if (_bits[1] < 0x10) Serial.print(0);
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Serial.print(_bits[1], HEX);
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Serial.print(" ");
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Serial.print(humidity, 1);
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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 result;
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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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int8_t dht::_readSensor(uint8_t pin, uint8_t wakeupDelay, uint8_t leadingZeroBits)
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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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uint8_t data = 0;
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uint8_t state = LOW;
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uint8_t pstate = LOW;
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uint16_t zeroLoop = DHTLIB_TIMEOUT;
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uint16_t delta = 0;
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leadingZeroBits = 40 - leadingZeroBits; // reverse counting...
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// replace digitalRead() with Direct Port Reads.
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// reduces footprint ~100 bytes => portability issue?
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// direct port read is about 3x faster
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uint8_t bit = digitalPinToBitMask(pin);
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uint8_t port = digitalPinToPort(pin);
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volatile uint8_t *PIR = portInputRegister(port);
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// REQUEST SAMPLE
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pinMode(pin, OUTPUT);
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digitalWrite(pin, LOW); // T-be
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if (wakeupDelay > 8) delay(wakeupDelay);
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else delayMicroseconds(wakeupDelay * 1000UL);
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digitalWrite(pin, HIGH); // T-go
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pinMode(pin, INPUT);
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uint16_t loopCount = DHTLIB_TIMEOUT * 2; // 200uSec max
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// while(digitalRead(pin) == HIGH)
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while ((*PIR & bit) != LOW )
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{
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if (--loopCount == 0)
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{
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return DHTLIB_ERROR_CONNECT;
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}
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}
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// GET ACKNOWLEDGE or TIMEOUT
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loopCount = DHTLIB_TIMEOUT;
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// while(digitalRead(pin) == LOW)
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while ((*PIR & bit) == LOW ) // T-rel
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{
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if (--loopCount == 0)
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{
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return DHTLIB_ERROR_ACK_L;
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}
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}
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loopCount = DHTLIB_TIMEOUT;
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// while(digitalRead(pin) == HIGH)
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while ((*PIR & bit) != LOW ) // T-reh
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{
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if (--loopCount == 0)
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{
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return DHTLIB_ERROR_ACK_H;
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}
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}
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loopCount = DHTLIB_TIMEOUT;
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// READ THE OUTPUT - 40 BITS => 5 BYTES
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for (uint8_t i = 40; i != 0; )
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{
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// WAIT FOR FALLING EDGE
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state = (*PIR & bit);
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if (state == LOW && pstate != LOW)
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{
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if (i > leadingZeroBits) // DHT22 first 6 bits are all zero !! DHT11 only 1
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{
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zeroLoop = min(zeroLoop, loopCount);
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delta = (DHTLIB_TIMEOUT - zeroLoop)/4;
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}
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else if ( loopCount <= (zeroLoop - delta) ) // long -> one
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{
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data |= 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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bits[idx] = data;
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idx++;
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data = 0;
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}
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// next bit
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--i;
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// reset timeout flag
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loopCount = DHTLIB_TIMEOUT;
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}
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pstate = state;
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// Check timeout
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if (--loopCount == 0)
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{
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return DHTLIB_ERROR_TIMEOUT;
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}
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}
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// pinMode(pin, OUTPUT);
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// digitalWrite(pin, 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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