Revision 1:731de3b11b74, committed 2015-12-29

Comitter:

zainzafar

Date:

Tue Dec 29 10:55:05 2015 +0000

Parent:

0:9ef709bfeb08

Commit message:

by Zain Zafar;

Changed in this revision

--- a/DHT/DHT.cpp	Tue Jul 10 13:11:23 2012 +0000
+++ b/DHT/DHT.cpp	Tue Dec 29 10:55:05 2015 +0000
@@ -9,7 +9,7 @@
  *
  *  Copyright (C) Wim De Roeve
  *                based on DHT22 sensor library by HO WING KIT
- *                Arduino DHT11 library 
+ *                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
@@ -29,127 +29,115 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-
+ 
 #include "DHT.h"
-
-#define DHT_DATA_BIT_COUNT 41
-
-DHT::DHT(PinName pin,int DHTtype) {
+ 
+#define DHT_DATA_BIT_COUNT 40
+ 
+DHT::DHT(PinName pin, eType DHTtype)
+{
     _pin = pin;
     _DHTtype = DHTtype;
-    _firsttime=true;
+    _firsttime = true;
 }
-
-DHT::~DHT() {
+ 
+DHT::~DHT()
+{
+    
 }
-
-int DHT::readData() {
-    int i, j, retryCount,b;
-    unsigned int bitTimes[DHT_DATA_BIT_COUNT];
-
+ 
+eError DHT::stall(DigitalInOut &io, int const level, int const max_time)
+{
+    int cnt = 0;
+    while (level == io) {
+        if (cnt > max_time) {
+            return ERROR_NO_PATIENCE;
+        }
+        cnt++;
+        wait_us(1);
+    }
+    return ERROR_NONE;
+}
+ 
+eError DHT::readData()
+{
+    uint8_t i = 0, j = 0, b = 0, data_valid = 0;
+    uint32_t bit_value[DHT_DATA_BIT_COUNT] = {0};
+ 
     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;
+ 
+    // IO must be in hi state to start
+    if (ERROR_NONE != stall(DHT_io, 0, 250)) {
+        return BUS_BUSY;
     }
-
-    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));
-
-
+ 
+    // start the transfer
     DHT_io.output();
     DHT_io = 0;
-    wait_ms(18);
+    // only 500uS for DHT22 but 18ms for DHT11
+    (_DHTtype == 11) ? wait_ms(18) : wait(1);
     DHT_io = 1;
-    wait_us(40);
+    wait_us(30);
     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 till the sensor grabs the bus
+    if (ERROR_NONE != stall(DHT_io, 1, 40)) {
+        return ERROR_NOT_PRESENT;
     }
-
-    wait_us(80);
-
+    // sensor should signal low 80us and then hi 80us
+    if (ERROR_NONE != stall(DHT_io, 0, 100)) {
+        return ERROR_SYNC_TIMEOUT;
+    }
+    if (ERROR_NONE != stall(DHT_io, 1, 100)) {
+        return ERROR_NO_PATIENCE;
+    }
+    // capture the data
     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);
+            if (ERROR_NONE != stall(DHT_io, 0, 75)) {
+                return ERROR_DATA_TIMEOUT;
+            }
+            // logic 0 is 28us max, 1 is 70us
             wait_us(40);
-            bitTimes[i*8+j]=DHT_io;
-
-            int count = 0;
-            while (DHT_io == 1 && count < 100) {
-                wait_us(1);
-                count++;
+            bit_value[i*8+j] = DHT_io;
+            if (ERROR_NONE != stall(DHT_io, 1, 50)) {
+                return ERROR_DATA_TIMEOUT;
             }
         }
     }
-    DHT_io.output();
-    DHT_io = 1;
+    // store the data
     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));
+            if (bit_value[i*8+j] == 1) {
+                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)) {
+ 
+    // uncomment to see the checksum error if it exists
+    //printf(" 0x%02x + 0x%02x + 0x%02x + 0x%02x = 0x%02x \n", DHT_data[0], DHT_data[1], DHT_data[2], DHT_data[3], DHT_data[4]);
+    data_valid = DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3];
+    if (DHT_data[4] == data_valid) {
         _lastReadTime = currentTime;
-        _lastTemperature=CalcTemperature();
-        _lastHumidity=CalcHumidity();
-
+        _lastTemperature = CalcTemperature();
+        _lastHumidity = CalcHumidity();
+ 
     } else {
         err = ERROR_CHECKSUM;
     }
-
+ 
     return err;
-
+ 
 }
-
-float DHT::CalcTemperature() {
+ 
+float DHT::CalcTemperature()
+{
     int v;
-
+ 
     switch (_DHTtype) {
         case DHT11:
             v = DHT_data[2];
@@ -165,22 +153,26 @@
     }
     return 0;
 }
-
-float DHT::ReadHumidity() {
+ 
+float DHT::ReadHumidity()
+{
     return _lastHumidity;
 }
-
-float DHT::ConvertCelciustoFarenheit(float celsius) {
+ 
+float DHT::ConvertCelciustoFarenheit(float const celsius)
+{
     return celsius * 9 / 5 + 32;
 }
-
-float DHT::ConvertCelciustoKelvin(float celsius) {
+ 
+float DHT::ConvertCelciustoKelvin(float const celsius)
+{
     return celsius + 273.15;
 }
-
+ 
 // dewPoint function NOAA
 // reference: http://wahiduddin.net/calc/density_algorithms.htm
-float DHT::CalcdewPoint(float celsius, float humidity) {
+float DHT::CalcdewPoint(float const celsius, float const humidity)
+{
     float A0= 373.15/(273.15 + celsius);
     float SUM = -7.90298 * (A0-1);
     SUM += 5.02808 * log10(A0);
@@ -191,20 +183,21 @@
     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 DHT::CalcdewPointFast(float const celsius, float const 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 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) {
+ 
+float DHT::ReadTemperature(eScale Scale)
+{
     if (Scale == FARENHEIT)
         return ConvertCelciustoFarenheit(_lastTemperature);
     else if (Scale == KELVIN)
@@ -212,10 +205,11 @@
     else
         return _lastTemperature;
 }
-
-float DHT::CalcHumidity() {
+ 
+float DHT::CalcHumidity()
+{
     int v;
-
+ 
     switch (_DHTtype) {
         case DHT11:
             v = DHT_data[0];
@@ -228,6 +222,4 @@
             return float(v);
     }
     return 0;
-}
-
-
+}
\ No newline at end of file

--- a/DHT/DHT.h	Tue Jul 10 13:11:23 2012 +0000
+++ b/DHT/DHT.h	Tue Dec 29 10:55:05 2015 +0000
@@ -1,10 +1,10 @@
-/* 
- *  DHT Library for  Digital-output Humidity and Temperature sensors 
- *  
+/*
+ *  DHT Library for  Digital-output Humidity and Temperature sensors
+ *
  *  Works with DHT11, DHT21, DHT22
  *             SEN11301P,  Grove - Temperature&Humidity Sensor     (Seeed Studio)
  *             SEN51035P,  Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
- *             AM2302   ,  temperature-humidity sensor    
+ *             AM2302   ,  temperature-humidity sensor
  *             RHT01,RHT02, RHT03    ,  Humidity and Temperature Sensor         (Sparkfun)
  *
  *  Copyright (C) Wim De Roeve
@@ -29,66 +29,71 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-
+ 
 #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
-    } ;
-
+ 
+typedef enum eType eType;
+enum eType {
+    DHT11     = 11,
+    SEN11301P = 11,
+    RHT01     = 11,
+    DHT22     = 22,
+    AM2302    = 22,
+    SEN51035P = 22,
+    RHT02     = 22,
+    RHT03     = 22
+};
+ 
+typedef enum eError eError;
 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 {
-
+    BUS_BUSY,
+    ERROR_NOT_PRESENT,
+    ERROR_ACK_TOO_LONG,
+    ERROR_SYNC_TIMEOUT,
+    ERROR_DATA_TIMEOUT,
+    ERROR_CHECKSUM,
+    ERROR_NO_PATIENCE
+};
+ 
+typedef enum eScale eScale;
+enum eScale {
+    CELCIUS = 0,
+    FARENHEIT,
+    KELVIN
+};
+ 
+ 
+class DHT
+{
+ 
 public:
-
-    DHT(PinName pin,int DHTtype);
+ 
+    DHT(PinName pin, eType DHTtype);
     ~DHT();
-    int readData(void);
+    eError readData(void);
     float ReadHumidity(void);
-    float ReadTemperature(eScale Scale);
-    float CalcdewPoint(float celsius, float humidity);
-    float CalcdewPointFast(float celsius, float humidity);
-
+    float ReadTemperature(eScale const Scale);
+    float CalcdewPoint(float const celsius, float const humidity);
+    float CalcdewPointFast(float const celsius, float const humidity);
+ 
 private:
     time_t  _lastReadTime;
     float _lastTemperature;
     float _lastHumidity;
     PinName _pin;
     bool _firsttime;
-    int _DHTtype;
-    int DHT_data[6];
+    eType _DHTtype;
+    uint8_t DHT_data[5];
     float CalcTemperature();
     float CalcHumidity();
-    float ConvertCelciustoFarenheit(float);
-    float ConvertCelciustoKelvin(float);
-
+    float ConvertCelciustoFarenheit(float const);
+    float ConvertCelciustoKelvin(float const);
+    eError stall(DigitalInOut &io, int const level, int const max_time);
+ 
 };
-
-#endif
+ 
+#endif
\ No newline at end of file

--- a/main.cpp	Tue Jul 10 13:11:23 2012 +0000
+++ b/main.cpp	Tue Dec 29 10:55:05 2015 +0000
@@ -2,26 +2,40 @@
 #include "DHT.h"
 
 DigitalOut myled(LED1);
+DigitalInOut data_pin(A0); // Activate digital in
+DigitalInOut data_pin(A1); // Activate digital in
+Serial pc(SERIAL_TX, SERIAL_RX); // Initialize UART connection
+Serial blutooth(PA_9, PA_10);//Tx, Rx
+Timer tmr; //initialize timer
+uint64_t adat; // 64 bit variable for temporary data
+int i;
 
-DHT sensor(p23,SEN11301P); // Use the SEN11301P sensor
+// Use a terminal program (eg. TeraTerm).
+//Timer tmr; //initialize timer
+
+
+DHT sensor(A0,SEN11301P); // Use the SEN11301P sensor
 
 int main() {
     int err;
-    printf("\r\nDHT Test program");
-    printf("\r\n******************\r\n");
+    pc.printf("\r\nDHT Test program");
+    pc.printf("\r\n******************\r\n");
     wait(1); // wait 1 second for device stable status
     while (1) {
         myled = 1;
+        wait(2);
         err = sensor.readData();
         if (err == 0) {
-            printf("Temperature is %4.2f C \r\n",sensor.ReadTemperature(CELCIUS));
-            printf("Temperature is %4.2f F \r\n",sensor.ReadTemperature(FARENHEIT));
-            printf("Temperature is %4.2f K \r\n",sensor.ReadTemperature(KELVIN));
-            printf("Humidity is %4.2f \r\n",sensor.ReadHumidity());
-            printf("Dew point is %4.2f  \r\n",sensor.CalcdewPoint(sensor.ReadTemperature(CELCIUS), sensor.ReadHumidity()));
-            printf("Dew point (fast) is %4.2f  \r\n",sensor.CalcdewPointFast(sensor.ReadTemperature(CELCIUS), sensor.ReadHumidity()));
+            
+            pc.printf("Temperature is %4.2f C \r\n",sensor.ReadTemperature(CELCIUS));
+            pc.printf("Temperature is %4.2f F \r\n",sensor.ReadTemperature(FARENHEIT));
+            pc.printf("Temperature is %4.2f K \r\n",sensor.ReadTemperature(KELVIN));
+            pc.printf("Humidity is %4.2f \r\n",sensor.ReadHumidity());
+            pc.printf("Dew point is %4.2f \r\n",sensor.CalcdewPoint(sensor.ReadTemperature(CELCIUS), sensor.ReadHumidity()));
+            pc.printf("Dew point (fast) is %4.2f  \r\n",sensor.CalcdewPointFast(sensor.ReadTemperature(CELCIUS), sensor.ReadHumidity()));
+            pc.printf("\n\n\n");
         } else
-            printf("\r\nErr %i \n",err);
+            pc.printf("\r\nErr %i \n",err);
         myled = 0;
         wait(5);
     }

--- a/mbed.bld	Tue Jul 10 13:11:23 2012 +0000
+++ b/mbed.bld	Tue Dec 29 10:55:05 2015 +0000
@@ -1,1 +1,1 @@
-http://mbed.org/users/mbed_official/code/mbed/builds/737756e0b479
+http://mbed.org/users/mbed_official/code/mbed/builds/4336505e4b1c
\ No newline at end of file