mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
162 lines
3.5 KiB
C++
162 lines
3.5 KiB
C++
//
|
|
// FILE: dht.cpp
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.1.07
|
|
// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
|
|
// URL: http://arduino.cc/playground/Main/DHTLib
|
|
//
|
|
// HISTORY:
|
|
// 0.1.07 added support for DHT21
|
|
// 0.1.06 minimize footprint (2012-12-27)
|
|
// 0.1.05 fixed negative temperature bug (thanks to Roseman)
|
|
// 0.1.04 improved readability of code using DHTLIB_OK in code
|
|
// 0.1.03 added error values for temp and humidity when read failed
|
|
// 0.1.02 added error codes
|
|
// 0.1.01 added support for Arduino 1.0, fixed typos (31/12/2011)
|
|
// 0.1.0 by Rob Tillaart (01/04/2011)
|
|
//
|
|
// inspired by DHT11 library
|
|
//
|
|
// Released to the public domain
|
|
//
|
|
|
|
#include "dht.h"
|
|
|
|
#define TIMEOUT (F_CPU/1600) // unsigned int in code, for higher CPU speeds this might exceed MAXINT.
|
|
|
|
/////////////////////////////////////////////////////
|
|
//
|
|
// PUBLIC
|
|
//
|
|
|
|
// return values:
|
|
// DHTLIB_OK
|
|
// DHTLIB_ERROR_CHECKSUM
|
|
// DHTLIB_ERROR_TIMEOUT
|
|
int dht::read11(uint8_t pin)
|
|
{
|
|
// READ VALUES
|
|
int rv = read(pin);
|
|
if (rv != DHTLIB_OK)
|
|
{
|
|
humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?
|
|
temperature = DHTLIB_INVALID_VALUE; // invalid value
|
|
return rv;
|
|
}
|
|
|
|
// CONVERT AND STORE
|
|
humidity = bits[0]; // bit[1] == 0;
|
|
temperature = bits[2]; // bits[3] == 0;
|
|
|
|
// TEST CHECKSUM
|
|
// bits[1] && bits[3] both 0
|
|
uint8_t sum = bits[0] + bits[2];
|
|
if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM;
|
|
|
|
return DHTLIB_OK;
|
|
}
|
|
|
|
// return values:
|
|
// DHTLIB_OK
|
|
// DHTLIB_ERROR_CHECKSUM
|
|
// DHTLIB_ERROR_TIMEOUT
|
|
int dht::read21(uint8_t pin)
|
|
{
|
|
return read22(pin); // dataformat identical to DHT22
|
|
}
|
|
|
|
// return values:
|
|
// DHTLIB_OK
|
|
// DHTLIB_ERROR_CHECKSUM
|
|
// DHTLIB_ERROR_TIMEOUT
|
|
int dht::read22(uint8_t pin)
|
|
{
|
|
// READ VALUES
|
|
int rv = read(pin);
|
|
if (rv != DHTLIB_OK)
|
|
{
|
|
humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?
|
|
temperature = DHTLIB_INVALID_VALUE; // invalid value
|
|
return rv; // propagate error value
|
|
}
|
|
|
|
// CONVERT AND STORE
|
|
humidity = word(bits[0], bits[1]) * 0.1;
|
|
|
|
if (bits[2] & 0x80) // negative temperature
|
|
{
|
|
temperature = -0.1 * word(bits[2] & 0x7F, bits[3]);
|
|
}
|
|
else
|
|
{
|
|
temperature = 0.1 * word(bits[2], bits[3]);
|
|
}
|
|
|
|
// TEST CHECKSUM
|
|
uint8_t sum = bits[0] + bits[1] + bits[2] + bits[3];
|
|
if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM;
|
|
|
|
return DHTLIB_OK;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////
|
|
//
|
|
// PRIVATE
|
|
//
|
|
|
|
// return values:
|
|
// DHTLIB_OK
|
|
// DHTLIB_ERROR_TIMEOUT
|
|
int dht::read(uint8_t pin)
|
|
{
|
|
// INIT BUFFERVAR TO RECEIVE DATA
|
|
uint8_t cnt = 7;
|
|
uint8_t idx = 0;
|
|
|
|
// EMPTY BUFFER
|
|
for (uint8_t i=0; i< 5; i++) bits[i] = 0;
|
|
|
|
// REQUEST SAMPLE
|
|
pinMode(pin, OUTPUT);
|
|
digitalWrite(pin, LOW);
|
|
delay(20);
|
|
digitalWrite(pin, HIGH);
|
|
delayMicroseconds(40);
|
|
pinMode(pin, INPUT);
|
|
|
|
// GET ACKNOWLEDGE or TIMEOUT
|
|
unsigned int loopCnt = TIMEOUT;
|
|
while(digitalRead(pin) == LOW)
|
|
if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
|
|
|
|
loopCnt = TIMEOUT;
|
|
while(digitalRead(pin) == HIGH)
|
|
if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
|
|
|
|
// READ THE OUTPUT - 40 BITS => 5 BYTES
|
|
for (uint8_t i=0; i<40; i++)
|
|
{
|
|
loopCnt = TIMEOUT;
|
|
while(digitalRead(pin) == LOW)
|
|
if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
|
|
|
|
unsigned long t = micros();
|
|
|
|
loopCnt = TIMEOUT;
|
|
while(digitalRead(pin) == HIGH)
|
|
if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
|
|
|
|
if ((micros() - t) > 40) bits[idx] |= (1 << cnt);
|
|
if (cnt == 0) // next byte?
|
|
{
|
|
cnt = 7;
|
|
idx++;
|
|
}
|
|
else cnt--;
|
|
}
|
|
|
|
return DHTLIB_OK;
|
|
}
|
|
//
|
|
// END OF FILE
|
|
//
|