Juan Moreno / DHT

Library For DHT

Dependents:   CharlieProject

DHT/DHT.cpp@0:78419284215c, 2019-07-11 (annotated)

Committer:
junmorenodi
Date:
Thu Jul 11 14:49:35 2019 +0000
Revision:
0:78419284215c
qwert

Who changed what in which revision?

UserRevisionLine numberNew contents of line
junmorenodi 0:78419284215c 1 #include "DHT.h"
junmorenodi 0:78419284215c 2
junmorenodi 0:78419284215c 3 #define DHT_DATA_BIT_COUNT 41
junmorenodi 0:78419284215c 4
junmorenodi 0:78419284215c 5 DHT::DHT(PinName pin,int DHTtype) {
junmorenodi 0:78419284215c 6 _pin = pin;
junmorenodi 0:78419284215c 7 _DHTtype = DHTtype;
junmorenodi 0:78419284215c 8 _firsttime=true;
junmorenodi 0:78419284215c 9 }
junmorenodi 0:78419284215c 10
junmorenodi 0:78419284215c 11 DHT::~DHT() {
junmorenodi 0:78419284215c 12 }
junmorenodi 0:78419284215c 13
junmorenodi 0:78419284215c 14 int DHT::readData() {
junmorenodi 0:78419284215c 15 int i, j, retryCount,b;
junmorenodi 0:78419284215c 16 unsigned int bitTimes[DHT_DATA_BIT_COUNT];
junmorenodi 0:78419284215c 17
junmorenodi 0:78419284215c 18 eError err = ERROR_NONE;
junmorenodi 0:78419284215c 19 time_t currentTime = time(NULL);
junmorenodi 0:78419284215c 20
junmorenodi 0:78419284215c 21 DigitalInOut DHT_io(_pin);
junmorenodi 0:78419284215c 22
junmorenodi 0:78419284215c 23 for (i = 0; i < DHT_DATA_BIT_COUNT; i++) {
junmorenodi 0:78419284215c 24 bitTimes[i] = 0;
junmorenodi 0:78419284215c 25 }
junmorenodi 0:78419284215c 26
junmorenodi 0:78419284215c 27 if (!_firsttime) {
junmorenodi 0:78419284215c 28 if (int(currentTime - _lastReadTime) < 2) {
junmorenodi 0:78419284215c 29 err = ERROR_NO_PATIENCE;
junmorenodi 0:78419284215c 30 return err;
junmorenodi 0:78419284215c 31 }
junmorenodi 0:78419284215c 32 } else {
junmorenodi 0:78419284215c 33 _firsttime=false;
junmorenodi 0:78419284215c 34 _lastReadTime=currentTime;
junmorenodi 0:78419284215c 35 }
junmorenodi 0:78419284215c 36 retryCount = 0;
junmorenodi 0:78419284215c 37
junmorenodi 0:78419284215c 38 do {
junmorenodi 0:78419284215c 39 if (retryCount > 125) {
junmorenodi 0:78419284215c 40 err = BUS_BUSY;
junmorenodi 0:78419284215c 41 return err;
junmorenodi 0:78419284215c 42 }
junmorenodi 0:78419284215c 43 retryCount ++;
junmorenodi 0:78419284215c 44 wait_us(2);
junmorenodi 0:78419284215c 45 } while ((DHT_io==0));
junmorenodi 0:78419284215c 46
junmorenodi 0:78419284215c 47
junmorenodi 0:78419284215c 48 DHT_io.output();
junmorenodi 0:78419284215c 49 DHT_io = 0;
junmorenodi 0:78419284215c 50 wait_ms(18);
junmorenodi 0:78419284215c 51 DHT_io = 1;
junmorenodi 0:78419284215c 52 wait_us(40);
junmorenodi 0:78419284215c 53 DHT_io.input();
junmorenodi 0:78419284215c 54
junmorenodi 0:78419284215c 55 retryCount = 0;
junmorenodi 0:78419284215c 56 do {
junmorenodi 0:78419284215c 57 if (retryCount > 40) {
junmorenodi 0:78419284215c 58 err = ERROR_NOT_PRESENT;
junmorenodi 0:78419284215c 59 return err;
junmorenodi 0:78419284215c 60 }
junmorenodi 0:78419284215c 61 retryCount++;
junmorenodi 0:78419284215c 62 wait_us(1);
junmorenodi 0:78419284215c 63 } while ((DHT_io==1));
junmorenodi 0:78419284215c 64
junmorenodi 0:78419284215c 65 if (err != ERROR_NONE) {
junmorenodi 0:78419284215c 66 return err;
junmorenodi 0:78419284215c 67 }
junmorenodi 0:78419284215c 68
junmorenodi 0:78419284215c 69 wait_us(80);
junmorenodi 0:78419284215c 70
junmorenodi 0:78419284215c 71 for (i = 0; i < 5; i++) {
junmorenodi 0:78419284215c 72 for (j = 0; j < 8; j++) {
junmorenodi 0:78419284215c 73
junmorenodi 0:78419284215c 74 retryCount = 0;
junmorenodi 0:78419284215c 75 do {
junmorenodi 0:78419284215c 76 if (retryCount > 75) {
junmorenodi 0:78419284215c 77 err = ERROR_DATA_TIMEOUT;
junmorenodi 0:78419284215c 78 return err;
junmorenodi 0:78419284215c 79 }
junmorenodi 0:78419284215c 80 retryCount++;
junmorenodi 0:78419284215c 81 wait_us(1);
junmorenodi 0:78419284215c 82 } while (DHT_io == 0);
junmorenodi 0:78419284215c 83 wait_us(40);
junmorenodi 0:78419284215c 84 bitTimes[i*8+j]=DHT_io;
junmorenodi 0:78419284215c 85
junmorenodi 0:78419284215c 86 int count = 0;
junmorenodi 0:78419284215c 87 while (DHT_io == 1 && count < 100) {
junmorenodi 0:78419284215c 88 wait_us(1);
junmorenodi 0:78419284215c 89 count++;
junmorenodi 0:78419284215c 90 }
junmorenodi 0:78419284215c 91 }
junmorenodi 0:78419284215c 92 }
junmorenodi 0:78419284215c 93 DHT_io.output();
junmorenodi 0:78419284215c 94 DHT_io = 1;
junmorenodi 0:78419284215c 95 for (i = 0; i < 5; i++) {
junmorenodi 0:78419284215c 96 b=0;
junmorenodi 0:78419284215c 97 for (j=0; j<8; j++) {
junmorenodi 0:78419284215c 98 if (bitTimes[i*8+j+1] > 0) {
junmorenodi 0:78419284215c 99 b |= ( 1 << (7-j));
junmorenodi 0:78419284215c 100 }
junmorenodi 0:78419284215c 101 }
junmorenodi 0:78419284215c 102 DHT_data[i]=b;
junmorenodi 0:78419284215c 103 }
junmorenodi 0:78419284215c 104
junmorenodi 0:78419284215c 105 if (DHT_data[4] == ((DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3]) & 0xFF)) {
junmorenodi 0:78419284215c 106 _lastReadTime = currentTime;
junmorenodi 0:78419284215c 107 _lastTemperature=CalcTemperature();
junmorenodi 0:78419284215c 108 _lastHumidity=CalcHumidity();
junmorenodi 0:78419284215c 109
junmorenodi 0:78419284215c 110 } else {
junmorenodi 0:78419284215c 111 err = ERROR_CHECKSUM;
junmorenodi 0:78419284215c 112 }
junmorenodi 0:78419284215c 113
junmorenodi 0:78419284215c 114 return err;
junmorenodi 0:78419284215c 115
junmorenodi 0:78419284215c 116 }
junmorenodi 0:78419284215c 117
junmorenodi 0:78419284215c 118 float DHT::CalcTemperature() {
junmorenodi 0:78419284215c 119 int v;
junmorenodi 0:78419284215c 120 float outvalue;
junmorenodi 0:78419284215c 121 switch (_DHTtype) {
junmorenodi 0:78419284215c 122 case DHT11:
junmorenodi 0:78419284215c 123 v = DHT_data[2];
junmorenodi 0:78419284215c 124 return float(v);
junmorenodi 0:78419284215c 125 case DHT22:
junmorenodi 0:78419284215c 126 v = DHT_data[2] & 0x7F;
junmorenodi 0:78419284215c 127 v *= 256;
junmorenodi 0:78419284215c 128 v += DHT_data[3];
junmorenodi 0:78419284215c 129 outvalue=(float) v/10;
junmorenodi 0:78419284215c 130 if (DHT_data[2] & 0x80)
junmorenodi 0:78419284215c 131 outvalue *= -1;
junmorenodi 0:78419284215c 132 return outvalue;
junmorenodi 0:78419284215c 133 }
junmorenodi 0:78419284215c 134 return 0;
junmorenodi 0:78419284215c 135 }
junmorenodi 0:78419284215c 136
junmorenodi 0:78419284215c 137 float DHT::ReadHumidity() {
junmorenodi 0:78419284215c 138 return _lastHumidity;
junmorenodi 0:78419284215c 139 }
junmorenodi 0:78419284215c 140
junmorenodi 0:78419284215c 141 float DHT::ConvertCelciustoFarenheit(float celsius) {
junmorenodi 0:78419284215c 142 return celsius * 9 / 5 + 32;
junmorenodi 0:78419284215c 143 }
junmorenodi 0:78419284215c 144
junmorenodi 0:78419284215c 145 float DHT::ConvertCelciustoKelvin(float celsius) {
junmorenodi 0:78419284215c 146 return celsius + 273.15;
junmorenodi 0:78419284215c 147 }
junmorenodi 0:78419284215c 148
junmorenodi 0:78419284215c 149 // dewPoint function NOAA
junmorenodi 0:78419284215c 150 // reference: http://wahiduddin.net/calc/density_algorithms.htm
junmorenodi 0:78419284215c 151 float DHT::CalcdewPoint(float celsius, float humidity) {
junmorenodi 0:78419284215c 152 float A0= 373.15/(273.15 + celsius);
junmorenodi 0:78419284215c 153 float SUM = -7.90298 * (A0-1);
junmorenodi 0:78419284215c 154 SUM += 5.02808 * log10(A0);
junmorenodi 0:78419284215c 155 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
junmorenodi 0:78419284215c 156 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
junmorenodi 0:78419284215c 157 SUM += log10(1013.246);
junmorenodi 0:78419284215c 158 float VP = pow(10, SUM-3) * humidity;
junmorenodi 0:78419284215c 159 float T = log(VP/0.61078); // temp var
junmorenodi 0:78419284215c 160 return (241.88 * T) / (17.558-T);
junmorenodi 0:78419284215c 161 }
junmorenodi 0:78419284215c 162
junmorenodi 0:78419284215c 163 // delta max = 0.6544 wrt dewPoint()
junmorenodi 0:78419284215c 164 // 5x faster than dewPoint()
junmorenodi 0:78419284215c 165 // reference: http://en.wikipedia.org/wiki/Dew_point
junmorenodi 0:78419284215c 166 float DHT::CalcdewPointFast(float celsius, float humidity)
junmorenodi 0:78419284215c 167 {
junmorenodi 0:78419284215c 168 float a = 17.271;
junmorenodi 0:78419284215c 169 float b = 237.7;
junmorenodi 0:78419284215c 170 float temp = (a * celsius) / (b + celsius) + log(humidity/100);
junmorenodi 0:78419284215c 171 float Td = (b * temp) / (a - temp);
junmorenodi 0:78419284215c 172 return Td;
junmorenodi 0:78419284215c 173 }
junmorenodi 0:78419284215c 174
junmorenodi 0:78419284215c 175 float DHT::ReadTemperature(eScale Scale) {
junmorenodi 0:78419284215c 176 if (Scale == FARENHEIT)
junmorenodi 0:78419284215c 177 return ConvertCelciustoFarenheit(_lastTemperature);
junmorenodi 0:78419284215c 178 else if (Scale == KELVIN)
junmorenodi 0:78419284215c 179 return ConvertCelciustoKelvin(_lastTemperature);
junmorenodi 0:78419284215c 180 else
junmorenodi 0:78419284215c 181 return _lastTemperature;
junmorenodi 0:78419284215c 182 }
junmorenodi 0:78419284215c 183
junmorenodi 0:78419284215c 184 float DHT::CalcHumidity() {
junmorenodi 0:78419284215c 185 int v;
junmorenodi 0:78419284215c 186 float outvalue;
junmorenodi 0:78419284215c 187
junmorenodi 0:78419284215c 188 switch (_DHTtype) {
junmorenodi 0:78419284215c 189 case DHT11:
junmorenodi 0:78419284215c 190 v = DHT_data[0];
junmorenodi 0:78419284215c 191 return float(v);
junmorenodi 0:78419284215c 192 case DHT22:
junmorenodi 0:78419284215c 193 v = DHT_data[0];
junmorenodi 0:78419284215c 194 v *= 256;
junmorenodi 0:78419284215c 195 v += DHT_data[1];
junmorenodi 0:78419284215c 196 outvalue=(float) v/10;
junmorenodi 0:78419284215c 197 return outvalue;
junmorenodi 0:78419284215c 198 }
junmorenodi 0:78419284215c 199 return 0;
junmorenodi 0:78419284215c 200 }
junmorenodi 0:78419284215c 201
junmorenodi 0:78419284215c 202