标题:
arduino 温湿度传感器dht11程序
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作者:
riceCake
时间:
2020-7-22 10:13
标题:
arduino 温湿度传感器dht11程序
//
// FILE: dht22.cpp
// VERSION: 0.1.00
// PURPOSE: DHT22 Temperature & Humidity Sensor library for Arduino
//
// DATASHEET:
//
// HISTORY:
// 0.1.0 by Rob Tillaart (01/04/2011)
// inspired by DHT11 library
//
#include "dht.h"
#define TIMEOUT 10000
/////////////////////////////////////////////////////
//
// PUBLIC
//
// return values:
// 0 : OK
// -1 : checksum error
// -2 : timeout
int dht::read11(uint8_t pin)
{
// READ VALUES
int rv = read(pin);
if (rv != 0) return rv;
// CONVERT AND STORE
humidity = bits[0]; // bit[1] == 0;
temperature = bits[2]; // bits[3] == 0;
// TEST CHECKSUM
uint8_t sum = bits[0] + bits[2]; // bits[1] && bits[3] both 0
if (bits[4] != sum) return -1;
return 0;
}
// return values:
// 0 : OK
// -1 : checksum error
// -2 : timeout
int dht::read22(uint8_t pin)
{
// READ VALUES
int rv = read(pin);
if (rv != 0) return rv;
// CONVERT AND STORE
humidity = word(bits[0], bits[1]) * 0.1;
int sign = 1;
if (bits[2] & 0x80) // negative temperature
{
bits[2] = bits[2] & 0x7F;
sign = -1;
}
temperature = sign * word(bits[2], bits[3]) * 0.1;
// TEST CHECKSUM
uint8_t sum = bits[0] + bits[1] + bits[2] + bits[3];
if (bits[4] != sum) return -1;
return 0;
}
/////////////////////////////////////////////////////
//
// PRIVATE
//
// return values:
// 0 : OK
// -2 : timeout
int dht::read(uint8_t pin)
{
// INIT BUFFERVAR TO RECEIVE DATA
uint8_t cnt = 7;
uint8_t idx = 0;
// EMPTY BUFFER
for (int 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 -2;
loopCnt = TIMEOUT;
while(digitalRead(pin) == HIGH)
if (loopCnt-- == 0) return -2;
// READ THE OUTPUT - 40 BITS => 5 BYTES
for (int i=0; i<40; i++)
{
loopCnt = TIMEOUT;
while(digitalRead(pin) == LOW)
if (loopCnt-- == 0) return -2;
unsigned long t = micros();
loopCnt = TIMEOUT;
while(digitalRead(pin) == HIGH)
if (loopCnt-- == 0) return -2;
if ((micros() - t) > 40) bits[idx] |= (1 << cnt);
if (cnt == 0) // next byte?
{
cnt = 7;
idx++;
}
else cnt--;
}
return 0;
}
//
// END OF FILE
//
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