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+ 0.1.18 fixed support for DHT11 again

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rob tillaart 2014-11-25 19:40:25 +01:00
parent 94a48c2283
commit baa1e15833
3 changed files with 24 additions and 18 deletions
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28
libraries/DHTlib/dht.cpp
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@ -1,11 +1,12 @@
//
// FILE: dht.cpp
// AUTHOR: Rob Tillaart
// VERSION: 0.1.17
// VERSION: 0.1.18
// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
// URL: http://arduino.cc/playground/Main/DHTLib
//
// HISTORY:
// 0.1.18 version 1.16/17 broke the DHT11 - FIXED
// 0.1.17 replaced micros() with adaptive loopcount
// removed DHTLIB_INVALID_VALUE
// added DHTLIB_ERROR_CONNECT
@ -43,11 +44,11 @@
int dht::read11(uint8_t pin)
{
// READ VALUES
int result = _readSensor(pin, DHTLIB_DHT11_WAKEUP);
int result = _readSensor(pin, DHTLIB_DHT11_WAKEUP, DHTLIB_DHT11_LEADING_ZEROS);
// these bits are always zero, masking them reduces errors.
bits[0] &= 0x03;
bits[2] &= 0x83;
bits[0] &= 0x3F;
bits[2] &= 0x3F;
// CONVERT AND STORE
humidity = bits[0]; // bits[1] == 0;
@ -66,7 +67,7 @@ int dht::read11(uint8_t pin)
int dht::read(uint8_t pin)
{
// READ VALUES
int result = _readSensor(pin, DHTLIB_DHT_WAKEUP);
int result = _readSensor(pin, DHTLIB_DHT_WAKEUP, DHTLIB_DHT_LEADING_ZEROS);
// these bits are always zero, masking them reduces errors.
bits[0] &= 0x03;
@ -94,12 +95,20 @@ int dht::read(uint8_t pin)
// PRIVATE
//
int dht::_readSensor(uint8_t pin, uint8_t wakeupDelay)
int dht::_readSensor(uint8_t pin, uint8_t wakeupDelay, uint8_t leadingZeroBits)
{
// INIT BUFFERVAR TO RECEIVE DATA
uint8_t mask = 128;
uint8_t idx = 0;
uint8_t data = 0;
uint8_t state = LOW;
uint8_t pstate = LOW;
uint16_t zeroLoop = DHTLIB_TIMEOUT;
uint16_t delta = 0;
leadingZeroBits = 40 - leadingZeroBits; // reverse counting...
// replace digitalRead() with Direct Port Reads.
// reduces footprint ~100 bytes => portability issue?
// direct port read is about 3x faster
@ -136,12 +145,7 @@ int dht::_readSensor(uint8_t pin, uint8_t wakeupDelay)
if (--loopCount == 0) return DHTLIB_ERROR_ACK_H;
}
uint8_t data = 0;
uint8_t state = LOW;
uint8_t pstate = LOW;
loopCount = DHTLIB_TIMEOUT;
uint16_t zeroLoop = DHTLIB_TIMEOUT;
uint16_t delta = 0;
// READ THE OUTPUT - 40 BITS => 5 BYTES
for (uint8_t i = 40; i != 0; )
@ -150,7 +154,7 @@ int dht::_readSensor(uint8_t pin, uint8_t wakeupDelay)
state = (*PIR & bit);
if (state == LOW && pstate != LOW)
{
if (i > 34) // first 6 bits are all zero !!
if (i > leadingZeroBits) // DHT22 first 6 bits are all zero !! DHT11 only 1
{
zeroLoop = min(zeroLoop, loopCount);
delta = (DHTLIB_TIMEOUT - zeroLoop)/4;

9
libraries/DHTlib/dht.h
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@ -1,7 +1,7 @@
//
// FILE: dht.h
// AUTHOR: Rob Tillaart
// VERSION: 0.1.17
// VERSION: 0.1.18
// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
// URL: http://arduino.cc/playground/Main/DHTLib
//
@ -19,7 +19,7 @@
#include <Arduino.h>
#endif
#define DHT_LIB_VERSION "0.1.17"
#define DHT_LIB_VERSION "0.1.18"
#define DHTLIB_OK 0
#define DHTLIB_ERROR_CHECKSUM -1
@ -31,6 +31,9 @@
#define DHTLIB_DHT11_WAKEUP 18
#define DHTLIB_DHT_WAKEUP 1
#define DHTLIB_DHT11_LEADING_ZEROS 1
#define DHTLIB_DHT_LEADING_ZEROS 6
// max timeout is 100 usec.
// For a 16 Mhz proc 100 usec is 1600 clock cycles
// loops using DHTLIB_TIMEOUT use at least 4 clock cycli
@ -61,7 +64,7 @@ public:
private:
uint8_t bits[5]; // buffer to receive data
int _readSensor(uint8_t pin, uint8_t wakeupDelay);
int _readSensor(uint8_t pin, uint8_t wakeupDelay, uint8_t leadingZeroBits);
};
#endif
//

5
libraries/DHTlib/readme.txt
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@ -17,13 +17,12 @@ Digistump Digix @ 84 MHz
More information - http://playground.arduino.cc//Main/DHTLib -
Notes:
version 0.1.13 is the last stable version for AVR and ARM
version 0.1.13 is the last stable version for both AVR and ARM
version 0.1.14 and up are not compatible anymore with pre 1.0 Arduino
version 0.1.14 and up have breaking changes wrt ARM based arduino's e.g DUE.
version 0.1.15 is stable version for AVR only
version 0.1.16 and 0.1.17 have breaking changes for DHT11
version 0.1.18 works again for DHT11 (avr only)