Juan Moreno
Library For DHT
Revision 0:78419284215c, committed 2019-07-11
- Comitter:
- junmorenodi
- Date:
- Thu Jul 11 14:49:35 2019 +0000
- Commit message:
- qwert
Changed in this revision
diff -r 000000000000 -r 78419284215c DHT/DHT.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/DHT/DHT.cpp Thu Jul 11 14:49:35 2019 +0000
@@ -0,0 +1,202 @@
+#include "DHT.h"
+
+#define DHT_DATA_BIT_COUNT 41
+
+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];
+
+ eError err = ERROR_NONE;
+ time_t currentTime = time(NULL);
+
+ DigitalInOut DHT_io(_pin);
+
+ for (i = 0; i < DHT_DATA_BIT_COUNT; i++) {
+ bitTimes[i] = 0;
+ }
+
+ if (!_firsttime) {
+ if (int(currentTime - _lastReadTime) < 2) {
+ err = ERROR_NO_PATIENCE;
+ return err;
+ }
+ } else {
+ _firsttime=false;
+ _lastReadTime=currentTime;
+ }
+ retryCount = 0;
+
+ do {
+ if (retryCount > 125) {
+ err = BUS_BUSY;
+ return err;
+ }
+ retryCount ++;
+ wait_us(2);
+ } while ((DHT_io==0));
+
+
+ DHT_io.output();
+ DHT_io = 0;
+ wait_ms(18);
+ DHT_io = 1;
+ wait_us(40);
+ DHT_io.input();
+
+ 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;
+ }
+
+ wait_us(80);
+
+ for (i = 0; i < 5; i++) {
+ for (j = 0; j < 8; j++) {
+
+ 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;
+
+ 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;
+
+}
+
+float DHT::CalcTemperature() {
+ int v;
+ float outvalue;
+ switch (_DHTtype) {
+ case DHT11:
+ v = DHT_data[2];
+ return float(v);
+ case DHT22:
+ v = DHT_data[2] & 0x7F;
+ v *= 256;
+ v += DHT_data[3];
+ outvalue=(float) v/10;
+ if (DHT_data[2] & 0x80)
+ outvalue *= -1;
+ return outvalue;
+ }
+ 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;
+ float outvalue;
+
+ switch (_DHTtype) {
+ case DHT11:
+ v = DHT_data[0];
+ return float(v);
+ case DHT22:
+ v = DHT_data[0];
+ v *= 256;
+ v += DHT_data[1];
+ outvalue=(float) v/10;
+ return outvalue;
+ }
+ return 0;
+}
+
+
diff -r 000000000000 -r 78419284215c DHT/DHT.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/DHT/DHT.h Thu Jul 11 14:49:35 2019 +0000
@@ -0,0 +1,62 @@
+#ifndef MBED_DHT_H
+#define MBED_DHT_H
+
+#include "mbed.h"
+
+enum eType{
+ DHT11 = 11,
+ SEN11301P = 11,
+ RHT01 = 11,
+ DHT22 = 22,
+ AM2302 = 22,
+ SEN51035P = 22,
+ RHT02 = 22,
+ RHT03 = 22
+ } ;
+
+enum eError {
+ ERROR_NONE = 0,
+ BUS_BUSY =1,
+ ERROR_NOT_PRESENT =2 ,
+ ERROR_ACK_TOO_LONG =3 ,
+ ERROR_SYNC_TIMEOUT = 4,
+ ERROR_DATA_TIMEOUT =5 ,
+ ERROR_CHECKSUM = 6,
+ ERROR_NO_PATIENCE =7
+} ;
+
+typedef enum {
+ CELCIUS =0 ,
+ FARENHEIT =1,
+ KELVIN=2
+} eScale;
+
+
+class DHT {
+
+public:
+
+ DHT(PinName pin,int DHTtype);
+ ~DHT();
+ int readData(void);
+ float ReadHumidity(void);
+ float ReadTemperature(eScale Scale);
+ float CalcdewPoint(float celsius, float humidity);
+ float CalcdewPointFast(float celsius, float humidity);
+
+private:
+ time_t _lastReadTime;
+ float _lastTemperature;
+ float _lastHumidity;
+ PinName _pin;
+ bool _firsttime;
+ int _DHTtype;
+ int DHT_data[6];
+ float CalcTemperature();
+ float CalcHumidity();
+ float ConvertCelciustoFarenheit(float);
+ float ConvertCelciustoKelvin(float);
+
+};
+
+#endif
diff -r 000000000000 -r 78419284215c __MACOSX/DHT/._DHT.cpp Binary file __MACOSX/DHT/._DHT.cpp has changed
diff -r 000000000000 -r 78419284215c __MACOSX/DHT/._DHT.h Binary file __MACOSX/DHT/._DHT.h has changed