Moises Marangoni
realease DHT lib working with Nucleo Board Thanks Somlak Mangnimit
Fork of
DHT
by 
Wim De Roeve
Diff: DHT.cpp
- Revision:
- 1:932d451474dc
- Parent:
- 0:9b5b3200688f
--- a/DHT.cpp Mon Jul 09 19:47:43 2012 +0000
+++ b/DHT.cpp Sat Apr 19 18:05:38 2014 +0000
@@ -1,233 +1,134 @@
/*
* DHT Library for Digital-output Humidity and Temperature sensors
*
- * Works with DHT11, DHT22
- * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
- * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
- * AM2302 , temperature-humidity sensor
- * HM2303 , Digital-output humidity and temperature sensor
+ * Works with DHT11, DHT22 Nucleo Board tested on F103RB
*
- * Copyright (C) Wim De Roeve
+ * Copyright (C) Wim De Roeve
+ * ported to work on Nucleo Board:
+ * Moises Marangoni
+ * Somlak Mangnimit
* based on DHT22 sensor library by HO WING KIT
* Arduino DHT11 library
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documnetation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
*/
#include "DHT.h"
+#include "mbed.h"
#define DHT_DATA_BIT_COUNT 41
+//DigitalInOut data_pin(PA_10);
+
DHT::DHT(PinName pin,int DHTtype) {
_pin = pin;
_DHTtype = DHTtype;
- _firsttime=true;
+
+
}
DHT::~DHT() {
}
int DHT::readData() {
- int i, j, retryCount,b;
- unsigned int bitTimes[DHT_DATA_BIT_COUNT];
+ Timer tmr;
+ DigitalInOut data_pin(_pin);
+ // BUFFER TO RECEIVE
+ //uint8_t bits[5];
+ uint8_t cnt = 7;
+ uint8_t idx = 0;
+
+ tmr.stop();
+ tmr.reset();
- eError err = ERROR_NONE;
- time_t currentTime = time(NULL);
-
- DigitalInOut DHT_io(_pin);
+ // EMPTY BUFFER
+ for(int i=0; i< 5; i++) bits[i] = 0;
- for (i = 0; i < DHT_DATA_BIT_COUNT; i++) {
- bitTimes[i] = 0;
- }
+ // REQUEST SAMPLE
+ data_pin.output();
+ data_pin.write(0);
+ wait_ms(18);
+ data_pin.write(1);
+ wait_us(40);
+ data_pin.input();
- if (!_firsttime) {
- if (int(currentTime - _lastReadTime) < 2) {
- err = ERROR_NO_PATIENCE;
- return err;
- }
- } else {
- _firsttime=false;
- _lastReadTime=currentTime;
- }
- retryCount = 0;
+ // ACKNOWLEDGE or TIMEOUT
+ unsigned int loopCnt = 10000;
+
+ while(!data_pin.read())if(!loopCnt--)return DHTLIB_ERROR_TIMEOUT;
- do {
- if (retryCount > 125) {
- err = BUS_BUSY;
- return err;
- }
- retryCount ++;
- wait_us(2);
- } while ((DHT_io==0));
+ loopCnt = 10000;
+
+ while(data_pin.read())if(!loopCnt--)return DHTLIB_ERROR_TIMEOUT;
+ // READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
+ for(int i=0; i<40; i++){
+
+ loopCnt = 10000;
+
+ while(!data_pin.read())if(loopCnt-- == 0)return DHTLIB_ERROR_TIMEOUT;
+
+ //unsigned long t = micros();
+ tmr.start();
- DHT_io.output();
- DHT_io = 0;
- wait_ms(18);
- DHT_io = 1;
- wait_us(40);
- DHT_io.input();
+ loopCnt = 10000;
+
+ while(data_pin.read())if(!loopCnt--)return DHTLIB_ERROR_TIMEOUT;
- retryCount = 0;
- do {
- if (retryCount > 40) {
- err = ERROR_NOT_PRESENT;
- return err;
- }
- retryCount++;
- wait_us(1);
- } while ((DHT_io==1));
-
- if (err != ERROR_NONE) {
- return err;
+ if(tmr.read_us() > 40) bits[idx] |= (1 << cnt);
+
+ tmr.stop();
+ tmr.reset();
+
+ if(cnt == 0){ // next byte?
+
+ cnt = 7; // restart at MSB
+ idx++; // next byte!
+
+ }else cnt--;
+
}
-
- wait_us(80);
-
- for (i = 0; i < 5; i++) {
- for (j = 0; j < 8; j++) {
+ // WRITE TO RIGHT VARS
+ // as bits[1] and bits[3] are allways zero they are omitted in formulas.
+ //humidity = bits[0];
+ //temperature = bits[2];
- retryCount = 0;
- do {
- if (retryCount > 75) {
- err = ERROR_DATA_TIMEOUT;
- return err;
- }
- retryCount++;
- wait_us(1);
- } while (DHT_io == 0);
- wait_us(40);
- bitTimes[i*8+j]=DHT_io;
+ uint8_t sum = bits[0] + bits[2];
- int count = 0;
- while (DHT_io == 1 && count < 100) {
- wait_us(1);
- count++;
- }
- }
- }
- DHT_io.output();
- DHT_io = 1;
- for (i = 0; i < 5; i++) {
- b=0;
- for (j=0; j<8; j++) {
- if (bitTimes[i*8+j+1] > 0) {
- b |= ( 1 << (7-j));
- }
- }
- DHT_data[i]=b;
- }
-
- if (DHT_data[4] == ((DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3]) & 0xFF)) {
- _lastReadTime = currentTime;
- _lastTemperature=CalcTemperature();
- _lastHumidity=CalcHumidity();
-
- } else {
- err = ERROR_CHECKSUM;
- }
-
- return err;
-
+ if(bits[4] != sum)return DHTLIB_ERROR_CHECKSUM;
+
+ return DHTLIB_OK;
}
-
-float DHT::CalcTemperature() {
- int v;
+float DHT::ReadTemperature() {
+ //int retornotemp;
switch (_DHTtype) {
case DHT11:
- v = DHT_data[2];
- return float(v);
+ temperature = bits[2];
+ return float(temperature);
case DHT22:
- v = DHT_data[2] & 0x7F;
- v *= 256;
- v += DHT_data[3];
- v /= 10;
- if (DHT_data[2] & 0x80)
- v *= -1;
- return float(v);
+ temperature = bits[2] & 0x7F;
+ temperature *= 256;
+ temperature += bits[3];
+ temperature /= 10;
+ if (bits[2] & 0x80)
+ {temperature *= -1;}
+ return float(temperature);
}
return 0;
}
-float DHT::ReadHumidity() {
- return _lastHumidity;
-}
-
-float DHT::ConvertCelciustoFarenheit(float celsius) {
- return celsius * 9 / 5 + 32;
-}
-
-float DHT::ConvertCelciustoKelvin(float celsius) {
- return celsius + 273.15;
-}
-
-// dewPoint function NOAA
-// reference: http://wahiduddin.net/calc/density_algorithms.htm
-float DHT::CalcdewPoint(float celsius, float humidity) {
- float A0= 373.15/(273.15 + celsius);
- float SUM = -7.90298 * (A0-1);
- SUM += 5.02808 * log10(A0);
- SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
- SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
- SUM += log10(1013.246);
- float VP = pow(10, SUM-3) * humidity;
- float T = log(VP/0.61078); // temp var
- return (241.88 * T) / (17.558-T);
-}
-
-// delta max = 0.6544 wrt dewPoint()
-// 5x faster than dewPoint()
-// reference: http://en.wikipedia.org/wiki/Dew_point
-float DHT::CalcdewPointFast(float celsius, float humidity)
-{
- float a = 17.271;
- float b = 237.7;
- float temp = (a * celsius) / (b + celsius) + log(humidity/100);
- float Td = (b * temp) / (a - temp);
- return Td;
-}
-
-float DHT::ReadTemperature(eScale Scale) {
- if (Scale == FARENHEIT)
- return ConvertCelciustoFarenheit(_lastTemperature);
- else if (Scale == KELVIN)
- return ConvertCelciustoKelvin(_lastTemperature);
- else
- return _lastTemperature;
-}
-
-float DHT::CalcHumidity() {
- int v;
+int DHT::ReadHumidity() {
+ //int v;
switch (_DHTtype) {
case DHT11:
- v = DHT_data[0];
- return float(v);
+ humidity = bits[0];
+ return float(humidity);
case DHT22:
- v = DHT_data[0];
- v *= 256;
- v += DHT_data[1];
- v /= 10;
- return float(v);
+ humidity = bits[0];
+ humidity *= 256;
+ humidity += bits[1];
+ humidity /= 10;
+ return float(humidity);
}
return 0;
-}
-
-
+}
\ No newline at end of file