Zain Zafar / Mbed 2 deprecated DHT_TestProgram

DHT testprogram

Dependencies:   mbed

Fork of DHT_TestProgram by Wim De Roeve

DHT/DHT.cpp@1:731de3b11b74, 2015-12-29 (annotated)

Committer:
zainzafar
Date:
Tue Dec 29 10:55:05 2015 +0000
Revision:
1:731de3b11b74
Parent:
0:9ef709bfeb08 
by Zain Zafar;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Wimpie 0:9ef709bfeb08 1 /*
Wimpie 0:9ef709bfeb08 2 * DHT Library for Digital-output Humidity and Temperature sensors
Wimpie 0:9ef709bfeb08 3 *
Wimpie 0:9ef709bfeb08 4 * Works with DHT11, DHT22
Wimpie 0:9ef709bfeb08 5 * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
Wimpie 0:9ef709bfeb08 6 * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
Wimpie 0:9ef709bfeb08 7 * AM2302 , temperature-humidity sensor
Wimpie 0:9ef709bfeb08 8 * HM2303 , Digital-output humidity and temperature sensor
Wimpie 0:9ef709bfeb08 9 *
Wimpie 0:9ef709bfeb08 10 * Copyright (C) Wim De Roeve
Wimpie 0:9ef709bfeb08 11 * based on DHT22 sensor library by HO WING KIT
zainzafar 1:731de3b11b74 12 * Arduino DHT11 library
Wimpie 0:9ef709bfeb08 13 *
Wimpie 0:9ef709bfeb08 14 * Permission is hereby granted, free of charge, to any person obtaining a copy
Wimpie 0:9ef709bfeb08 15 * of this software and associated documnetation files (the "Software"), to deal
Wimpie 0:9ef709bfeb08 16 * in the Software without restriction, including without limitation the rights
Wimpie 0:9ef709bfeb08 17 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
Wimpie 0:9ef709bfeb08 18 * copies of the Software, and to permit persons to whom the Software is
Wimpie 0:9ef709bfeb08 19 * furished to do so, subject to the following conditions:
Wimpie 0:9ef709bfeb08 20 *
Wimpie 0:9ef709bfeb08 21 * The above copyright notice and this permission notice shall be included in
Wimpie 0:9ef709bfeb08 22 * all copies or substantial portions of the Software.
Wimpie 0:9ef709bfeb08 23 *
Wimpie 0:9ef709bfeb08 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Wimpie 0:9ef709bfeb08 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Wimpie 0:9ef709bfeb08 26 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
Wimpie 0:9ef709bfeb08 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Wimpie 0:9ef709bfeb08 28 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
Wimpie 0:9ef709bfeb08 29 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
Wimpie 0:9ef709bfeb08 30 * THE SOFTWARE.
Wimpie 0:9ef709bfeb08 31 */
zainzafar 1:731de3b11b74 32
Wimpie 0:9ef709bfeb08 33 #include "DHT.h"
zainzafar 1:731de3b11b74 34
zainzafar 1:731de3b11b74 35 #define DHT_DATA_BIT_COUNT 40
zainzafar 1:731de3b11b74 36
zainzafar 1:731de3b11b74 37 DHT::DHT(PinName pin, eType DHTtype)
zainzafar 1:731de3b11b74 38 {
Wimpie 0:9ef709bfeb08 39 _pin = pin;
Wimpie 0:9ef709bfeb08 40 _DHTtype = DHTtype;
zainzafar 1:731de3b11b74 41 _firsttime = true;
Wimpie 0:9ef709bfeb08 42 }
zainzafar 1:731de3b11b74 43
zainzafar 1:731de3b11b74 44 DHT::~DHT()
zainzafar 1:731de3b11b74 45 {
zainzafar 1:731de3b11b74 46
Wimpie 0:9ef709bfeb08 47 }
zainzafar 1:731de3b11b74 48
zainzafar 1:731de3b11b74 49 eError DHT::stall(DigitalInOut &io, int const level, int const max_time)
zainzafar 1:731de3b11b74 50 {
zainzafar 1:731de3b11b74 51 int cnt = 0;
zainzafar 1:731de3b11b74 52 while (level == io) {
zainzafar 1:731de3b11b74 53 if (cnt > max_time) {
zainzafar 1:731de3b11b74 54 return ERROR_NO_PATIENCE;
zainzafar 1:731de3b11b74 55 }
zainzafar 1:731de3b11b74 56 cnt++;
zainzafar 1:731de3b11b74 57 wait_us(1);
zainzafar 1:731de3b11b74 58 }
zainzafar 1:731de3b11b74 59 return ERROR_NONE;
zainzafar 1:731de3b11b74 60 }
zainzafar 1:731de3b11b74 61
zainzafar 1:731de3b11b74 62 eError DHT::readData()
zainzafar 1:731de3b11b74 63 {
zainzafar 1:731de3b11b74 64 uint8_t i = 0, j = 0, b = 0, data_valid = 0;
zainzafar 1:731de3b11b74 65 uint32_t bit_value[DHT_DATA_BIT_COUNT] = {0};
zainzafar 1:731de3b11b74 66
Wimpie 0:9ef709bfeb08 67 eError err = ERROR_NONE;
Wimpie 0:9ef709bfeb08 68 time_t currentTime = time(NULL);
zainzafar 1:731de3b11b74 69
Wimpie 0:9ef709bfeb08 70 DigitalInOut DHT_io(_pin);
zainzafar 1:731de3b11b74 71
zainzafar 1:731de3b11b74 72 // IO must be in hi state to start
zainzafar 1:731de3b11b74 73 if (ERROR_NONE != stall(DHT_io, 0, 250)) {
zainzafar 1:731de3b11b74 74 return BUS_BUSY;
Wimpie 0:9ef709bfeb08 75 }
zainzafar 1:731de3b11b74 76
zainzafar 1:731de3b11b74 77 // start the transfer
Wimpie 0:9ef709bfeb08 78 DHT_io.output();
Wimpie 0:9ef709bfeb08 79 DHT_io = 0;
zainzafar 1:731de3b11b74 80 // only 500uS for DHT22 but 18ms for DHT11
zainzafar 1:731de3b11b74 81 (_DHTtype == 11) ? wait_ms(18) : wait(1);
Wimpie 0:9ef709bfeb08 82 DHT_io = 1;
zainzafar 1:731de3b11b74 83 wait_us(30);
Wimpie 0:9ef709bfeb08 84 DHT_io.input();
zainzafar 1:731de3b11b74 85 // wait till the sensor grabs the bus
zainzafar 1:731de3b11b74 86 if (ERROR_NONE != stall(DHT_io, 1, 40)) {
zainzafar 1:731de3b11b74 87 return ERROR_NOT_PRESENT;
Wimpie 0:9ef709bfeb08 88 }
zainzafar 1:731de3b11b74 89 // sensor should signal low 80us and then hi 80us
zainzafar 1:731de3b11b74 90 if (ERROR_NONE != stall(DHT_io, 0, 100)) {
zainzafar 1:731de3b11b74 91 return ERROR_SYNC_TIMEOUT;
zainzafar 1:731de3b11b74 92 }
zainzafar 1:731de3b11b74 93 if (ERROR_NONE != stall(DHT_io, 1, 100)) {
zainzafar 1:731de3b11b74 94 return ERROR_NO_PATIENCE;
zainzafar 1:731de3b11b74 95 }
zainzafar 1:731de3b11b74 96 // capture the data
Wimpie 0:9ef709bfeb08 97 for (i = 0; i < 5; i++) {
Wimpie 0:9ef709bfeb08 98 for (j = 0; j < 8; j++) {
zainzafar 1:731de3b11b74 99 if (ERROR_NONE != stall(DHT_io, 0, 75)) {
zainzafar 1:731de3b11b74 100 return ERROR_DATA_TIMEOUT;
zainzafar 1:731de3b11b74 101 }
zainzafar 1:731de3b11b74 102 // logic 0 is 28us max, 1 is 70us
Wimpie 0:9ef709bfeb08 103 wait_us(40);
zainzafar 1:731de3b11b74 104 bit_value[i*8+j] = DHT_io;
zainzafar 1:731de3b11b74 105 if (ERROR_NONE != stall(DHT_io, 1, 50)) {
zainzafar 1:731de3b11b74 106 return ERROR_DATA_TIMEOUT;
Wimpie 0:9ef709bfeb08 107 }
Wimpie 0:9ef709bfeb08 108 }
Wimpie 0:9ef709bfeb08 109 }
zainzafar 1:731de3b11b74 110 // store the data
Wimpie 0:9ef709bfeb08 111 for (i = 0; i < 5; i++) {
Wimpie 0:9ef709bfeb08 112 b=0;
Wimpie 0:9ef709bfeb08 113 for (j=0; j<8; j++) {
zainzafar 1:731de3b11b74 114 if (bit_value[i*8+j] == 1) {
zainzafar 1:731de3b11b74 115 b |= (1 << (7-j));
Wimpie 0:9ef709bfeb08 116 }
Wimpie 0:9ef709bfeb08 117 }
Wimpie 0:9ef709bfeb08 118 DHT_data[i]=b;
Wimpie 0:9ef709bfeb08 119 }
zainzafar 1:731de3b11b74 120
zainzafar 1:731de3b11b74 121 // uncomment to see the checksum error if it exists
zainzafar 1:731de3b11b74 122 //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]);
zainzafar 1:731de3b11b74 123 data_valid = DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3];
zainzafar 1:731de3b11b74 124 if (DHT_data[4] == data_valid) {
Wimpie 0:9ef709bfeb08 125 _lastReadTime = currentTime;
zainzafar 1:731de3b11b74 126 _lastTemperature = CalcTemperature();
zainzafar 1:731de3b11b74 127 _lastHumidity = CalcHumidity();
zainzafar 1:731de3b11b74 128
Wimpie 0:9ef709bfeb08 129 } else {
Wimpie 0:9ef709bfeb08 130 err = ERROR_CHECKSUM;
Wimpie 0:9ef709bfeb08 131 }
zainzafar 1:731de3b11b74 132
Wimpie 0:9ef709bfeb08 133 return err;
zainzafar 1:731de3b11b74 134
Wimpie 0:9ef709bfeb08 135 }
zainzafar 1:731de3b11b74 136
zainzafar 1:731de3b11b74 137 float DHT::CalcTemperature()
zainzafar 1:731de3b11b74 138 {
Wimpie 0:9ef709bfeb08 139 int v;
zainzafar 1:731de3b11b74 140
Wimpie 0:9ef709bfeb08 141 switch (_DHTtype) {
Wimpie 0:9ef709bfeb08 142 case DHT11:
Wimpie 0:9ef709bfeb08 143 v = DHT_data[2];
Wimpie 0:9ef709bfeb08 144 return float(v);
Wimpie 0:9ef709bfeb08 145 case DHT22:
Wimpie 0:9ef709bfeb08 146 v = DHT_data[2] & 0x7F;
Wimpie 0:9ef709bfeb08 147 v *= 256;
Wimpie 0:9ef709bfeb08 148 v += DHT_data[3];
Wimpie 0:9ef709bfeb08 149 v /= 10;
Wimpie 0:9ef709bfeb08 150 if (DHT_data[2] & 0x80)
Wimpie 0:9ef709bfeb08 151 v *= -1;
Wimpie 0:9ef709bfeb08 152 return float(v);
Wimpie 0:9ef709bfeb08 153 }
Wimpie 0:9ef709bfeb08 154 return 0;
Wimpie 0:9ef709bfeb08 155 }
zainzafar 1:731de3b11b74 156
zainzafar 1:731de3b11b74 157 float DHT::ReadHumidity()
zainzafar 1:731de3b11b74 158 {
Wimpie 0:9ef709bfeb08 159 return _lastHumidity;
Wimpie 0:9ef709bfeb08 160 }
zainzafar 1:731de3b11b74 161
zainzafar 1:731de3b11b74 162 float DHT::ConvertCelciustoFarenheit(float const celsius)
zainzafar 1:731de3b11b74 163 {
Wimpie 0:9ef709bfeb08 164 return celsius * 9 / 5 + 32;
Wimpie 0:9ef709bfeb08 165 }
zainzafar 1:731de3b11b74 166
zainzafar 1:731de3b11b74 167 float DHT::ConvertCelciustoKelvin(float const celsius)
zainzafar 1:731de3b11b74 168 {
Wimpie 0:9ef709bfeb08 169 return celsius + 273.15;
Wimpie 0:9ef709bfeb08 170 }
zainzafar 1:731de3b11b74 171
Wimpie 0:9ef709bfeb08 172 // dewPoint function NOAA
Wimpie 0:9ef709bfeb08 173 // reference: http://wahiduddin.net/calc/density_algorithms.htm
zainzafar 1:731de3b11b74 174 float DHT::CalcdewPoint(float const celsius, float const humidity)
zainzafar 1:731de3b11b74 175 {
Wimpie 0:9ef709bfeb08 176 float A0= 373.15/(273.15 + celsius);
Wimpie 0:9ef709bfeb08 177 float SUM = -7.90298 * (A0-1);
Wimpie 0:9ef709bfeb08 178 SUM += 5.02808 * log10(A0);
Wimpie 0:9ef709bfeb08 179 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
Wimpie 0:9ef709bfeb08 180 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
Wimpie 0:9ef709bfeb08 181 SUM += log10(1013.246);
Wimpie 0:9ef709bfeb08 182 float VP = pow(10, SUM-3) * humidity;
Wimpie 0:9ef709bfeb08 183 float T = log(VP/0.61078); // temp var
Wimpie 0:9ef709bfeb08 184 return (241.88 * T) / (17.558-T);
Wimpie 0:9ef709bfeb08 185 }
zainzafar 1:731de3b11b74 186
Wimpie 0:9ef709bfeb08 187 // delta max = 0.6544 wrt dewPoint()
Wimpie 0:9ef709bfeb08 188 // 5x faster than dewPoint()
Wimpie 0:9ef709bfeb08 189 // reference: http://en.wikipedia.org/wiki/Dew_point
zainzafar 1:731de3b11b74 190 float DHT::CalcdewPointFast(float const celsius, float const humidity)
Wimpie 0:9ef709bfeb08 191 {
zainzafar 1:731de3b11b74 192 float a = 17.271;
zainzafar 1:731de3b11b74 193 float b = 237.7;
zainzafar 1:731de3b11b74 194 float temp = (a * celsius) / (b + celsius) + log(humidity/100);
zainzafar 1:731de3b11b74 195 float Td = (b * temp) / (a - temp);
zainzafar 1:731de3b11b74 196 return Td;
Wimpie 0:9ef709bfeb08 197 }
zainzafar 1:731de3b11b74 198
zainzafar 1:731de3b11b74 199 float DHT::ReadTemperature(eScale Scale)
zainzafar 1:731de3b11b74 200 {
Wimpie 0:9ef709bfeb08 201 if (Scale == FARENHEIT)
Wimpie 0:9ef709bfeb08 202 return ConvertCelciustoFarenheit(_lastTemperature);
Wimpie 0:9ef709bfeb08 203 else if (Scale == KELVIN)
Wimpie 0:9ef709bfeb08 204 return ConvertCelciustoKelvin(_lastTemperature);
Wimpie 0:9ef709bfeb08 205 else
Wimpie 0:9ef709bfeb08 206 return _lastTemperature;
Wimpie 0:9ef709bfeb08 207 }
zainzafar 1:731de3b11b74 208
zainzafar 1:731de3b11b74 209 float DHT::CalcHumidity()
zainzafar 1:731de3b11b74 210 {
Wimpie 0:9ef709bfeb08 211 int v;
zainzafar 1:731de3b11b74 212
Wimpie 0:9ef709bfeb08 213 switch (_DHTtype) {
Wimpie 0:9ef709bfeb08 214 case DHT11:
Wimpie 0:9ef709bfeb08 215 v = DHT_data[0];
Wimpie 0:9ef709bfeb08 216 return float(v);
Wimpie 0:9ef709bfeb08 217 case DHT22:
Wimpie 0:9ef709bfeb08 218 v = DHT_data[0];
Wimpie 0:9ef709bfeb08 219 v *= 256;
Wimpie 0:9ef709bfeb08 220 v += DHT_data[1];
Wimpie 0:9ef709bfeb08 221 v /= 10;
Wimpie 0:9ef709bfeb08 222 return float(v);
Wimpie 0:9ef709bfeb08 223 }
Wimpie 0:9ef709bfeb08 224 return 0;
zainzafar 1:731de3b11b74 225 }