Fontana Romain / Mbed 2 deprecated DHT11

Programme d'une sonde de température DHT 11 associée à de la sauvegarde de données sur clé USB et à l'affichage de ces données sur afficheur LCD

Dependencies:   FatFileSystemCpp mbed

DHT.cpp@0:ed0b4e66d2ad, 2015-06-02 (annotated)

Committer:
Fanta025
Date:
Tue Jun 02 14:19:54 2015 +0000
Revision:
0:ed0b4e66d2ad
Programme d'une sonde de temp?rature DHT 11 associ?e ? de la sauvegarde de donn?es sur USB et un affichage sur ?cran LCD

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Fanta025 0:ed0b4e66d2ad 1 /*
Fanta025 0:ed0b4e66d2ad 2 * DHT Library for Digital-output Humidity and Temperature sensors
Fanta025 0:ed0b4e66d2ad 3 *
Fanta025 0:ed0b4e66d2ad 4 * Works with DHT11, DHT22
Fanta025 0:ed0b4e66d2ad 5 * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
Fanta025 0:ed0b4e66d2ad 6 * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
Fanta025 0:ed0b4e66d2ad 7 * AM2302 , temperature-humidity sensor
Fanta025 0:ed0b4e66d2ad 8 * HM2303 , Digital-output humidity and temperature sensor
Fanta025 0:ed0b4e66d2ad 9 *
Fanta025 0:ed0b4e66d2ad 10 * Copyright (C) Wim De Roeve
Fanta025 0:ed0b4e66d2ad 11 * based on DHT22 sensor library by HO WING KIT
Fanta025 0:ed0b4e66d2ad 12 * Arduino DHT11 library
Fanta025 0:ed0b4e66d2ad 13 *
Fanta025 0:ed0b4e66d2ad 14 * Permission is hereby granted, free of charge, to any person obtaining a copy
Fanta025 0:ed0b4e66d2ad 15 * of this software and associated documnetation files (the "Software"), to deal
Fanta025 0:ed0b4e66d2ad 16 * in the Software without restriction, including without limitation the rights
Fanta025 0:ed0b4e66d2ad 17 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
Fanta025 0:ed0b4e66d2ad 18 * copies of the Software, and to permit persons to whom the Software is
Fanta025 0:ed0b4e66d2ad 19 * furished to do so, subject to the following conditions:
Fanta025 0:ed0b4e66d2ad 20 *
Fanta025 0:ed0b4e66d2ad 21 * The above copyright notice and this permission notice shall be included in
Fanta025 0:ed0b4e66d2ad 22 * all copies or substantial portions of the Software.
Fanta025 0:ed0b4e66d2ad 23 *
Fanta025 0:ed0b4e66d2ad 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Fanta025 0:ed0b4e66d2ad 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Fanta025 0:ed0b4e66d2ad 26 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
Fanta025 0:ed0b4e66d2ad 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Fanta025 0:ed0b4e66d2ad 28 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
Fanta025 0:ed0b4e66d2ad 29 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
Fanta025 0:ed0b4e66d2ad 30 * THE SOFTWARE.
Fanta025 0:ed0b4e66d2ad 31 */
Fanta025 0:ed0b4e66d2ad 32
Fanta025 0:ed0b4e66d2ad 33 #include "DHT.h"
Fanta025 0:ed0b4e66d2ad 34
Fanta025 0:ed0b4e66d2ad 35 #define DHT_DATA_BIT_COUNT 40
Fanta025 0:ed0b4e66d2ad 36
Fanta025 0:ed0b4e66d2ad 37 DHT::DHT(PinName pin, eType DHTtype)
Fanta025 0:ed0b4e66d2ad 38 {
Fanta025 0:ed0b4e66d2ad 39 _pin = pin;
Fanta025 0:ed0b4e66d2ad 40 _DHTtype = DHTtype;
Fanta025 0:ed0b4e66d2ad 41 _firsttime = true;
Fanta025 0:ed0b4e66d2ad 42 }
Fanta025 0:ed0b4e66d2ad 43
Fanta025 0:ed0b4e66d2ad 44 DHT::~DHT()
Fanta025 0:ed0b4e66d2ad 45 {
Fanta025 0:ed0b4e66d2ad 46
Fanta025 0:ed0b4e66d2ad 47 }
Fanta025 0:ed0b4e66d2ad 48
Fanta025 0:ed0b4e66d2ad 49 eError DHT::stall(DigitalInOut &io, int const level, int const max_time)
Fanta025 0:ed0b4e66d2ad 50 {
Fanta025 0:ed0b4e66d2ad 51 int cnt = 0;
Fanta025 0:ed0b4e66d2ad 52 while (level == io) {
Fanta025 0:ed0b4e66d2ad 53 if (cnt > max_time) {
Fanta025 0:ed0b4e66d2ad 54 return ERROR_NO_PATIENCE;
Fanta025 0:ed0b4e66d2ad 55 }
Fanta025 0:ed0b4e66d2ad 56 cnt++;
Fanta025 0:ed0b4e66d2ad 57 wait_us(1);
Fanta025 0:ed0b4e66d2ad 58 }
Fanta025 0:ed0b4e66d2ad 59 return ERROR_NONE;
Fanta025 0:ed0b4e66d2ad 60 }
Fanta025 0:ed0b4e66d2ad 61
Fanta025 0:ed0b4e66d2ad 62 eError DHT::readData()
Fanta025 0:ed0b4e66d2ad 63 {
Fanta025 0:ed0b4e66d2ad 64 uint8_t i = 0, j = 0, b = 0, data_valid = 0;
Fanta025 0:ed0b4e66d2ad 65 uint32_t bit_value[DHT_DATA_BIT_COUNT] = {0};
Fanta025 0:ed0b4e66d2ad 66
Fanta025 0:ed0b4e66d2ad 67 eError err = ERROR_NONE;
Fanta025 0:ed0b4e66d2ad 68 time_t currentTime = time(NULL);
Fanta025 0:ed0b4e66d2ad 69
Fanta025 0:ed0b4e66d2ad 70 DigitalInOut DHT_io(_pin);
Fanta025 0:ed0b4e66d2ad 71
Fanta025 0:ed0b4e66d2ad 72 // IO must be in hi state to start
Fanta025 0:ed0b4e66d2ad 73 if (ERROR_NONE != stall(DHT_io, 0, 250)) {
Fanta025 0:ed0b4e66d2ad 74 return BUS_BUSY;
Fanta025 0:ed0b4e66d2ad 75 }
Fanta025 0:ed0b4e66d2ad 76
Fanta025 0:ed0b4e66d2ad 77 // start the transfer
Fanta025 0:ed0b4e66d2ad 78 DHT_io.output();
Fanta025 0:ed0b4e66d2ad 79 DHT_io = 0;
Fanta025 0:ed0b4e66d2ad 80 // only 500uS for DHT22 but 18ms for DHT11
Fanta025 0:ed0b4e66d2ad 81 // *** RF : Le signal de démarrage consiste à un niveau de tension bas sur la ligne de données pour un minimum
Fanta025 0:ed0b4e66d2ad 82 //de 18 ms pour s'assurer que la DHT11 détecte, suivie par une tension de pull-up pour environ 40US.
Fanta025 0:ed0b4e66d2ad 83 (_DHTtype == 11) ? wait_ms(18) : wait(1);
Fanta025 0:ed0b4e66d2ad 84 DHT_io = 1;
Fanta025 0:ed0b4e66d2ad 85 wait_us(30);
Fanta025 0:ed0b4e66d2ad 86 DHT_io.input();
Fanta025 0:ed0b4e66d2ad 87 // wait till the sensor grabs the bus
Fanta025 0:ed0b4e66d2ad 88 if (ERROR_NONE != stall(DHT_io, 1, 40)) {
Fanta025 0:ed0b4e66d2ad 89 return ERROR_NOT_PRESENT;
Fanta025 0:ed0b4e66d2ad 90 }
Fanta025 0:ed0b4e66d2ad 91 // sensor should signal low 80us and then hi 80us
Fanta025 0:ed0b4e66d2ad 92 // *** RF : Une fois que la DHT11 détecte le signal de démarrage, il enverra un signal basse tension en réponse à ce niveau, ce qui
Fanta025 0:ed0b4e66d2ad 93 //dure 80US. Ensuite, il fait passer le niveau de tension de faible à élevé et le maintient pour 80US.
Fanta025 0:ed0b4e66d2ad 94 if (ERROR_NONE != stall(DHT_io, 0, 100)) {
Fanta025 0:ed0b4e66d2ad 95 return ERROR_SYNC_TIMEOUT;
Fanta025 0:ed0b4e66d2ad 96 }
Fanta025 0:ed0b4e66d2ad 97 if (ERROR_NONE != stall(DHT_io, 1, 100)) {
Fanta025 0:ed0b4e66d2ad 98 return ERROR_NO_PATIENCE;
Fanta025 0:ed0b4e66d2ad 99 }
Fanta025 0:ed0b4e66d2ad 100 // capture the data
Fanta025 0:ed0b4e66d2ad 101 for (i = 0; i < 5; i++) {
Fanta025 0:ed0b4e66d2ad 102 for (j = 0; j < 8; j++) {
Fanta025 0:ed0b4e66d2ad 103 if (ERROR_NONE != stall(DHT_io, 0, 75)) {
Fanta025 0:ed0b4e66d2ad 104 return ERROR_DATA_TIMEOUT;
Fanta025 0:ed0b4e66d2ad 105 }
Fanta025 0:ed0b4e66d2ad 106 // logic 0 is 28us max, 1 is 70us
Fanta025 0:ed0b4e66d2ad 107 // *** RF : un bit 1 a une durée de 27uS en haute tension, un bit 0 a une durée de 70uS avec un niveau haut de tension
Fanta025 0:ed0b4e66d2ad 108 //Lorsque les données du dernier bit est transmis, DHT11 tire le niveau de tension vers le bas et de garde pour 50us,
Fanta025 0:ed0b4e66d2ad 109 wait_us(40);
Fanta025 0:ed0b4e66d2ad 110 bit_value[i*8+j] = DHT_io;
Fanta025 0:ed0b4e66d2ad 111 if (ERROR_NONE != stall(DHT_io, 1, 50)) {
Fanta025 0:ed0b4e66d2ad 112 return ERROR_DATA_TIMEOUT;
Fanta025 0:ed0b4e66d2ad 113 }
Fanta025 0:ed0b4e66d2ad 114 }
Fanta025 0:ed0b4e66d2ad 115 }
Fanta025 0:ed0b4e66d2ad 116 // store the data
Fanta025 0:ed0b4e66d2ad 117 for (i = 0; i < 5; i++) {
Fanta025 0:ed0b4e66d2ad 118 b=0;
Fanta025 0:ed0b4e66d2ad 119 for (j=0; j<8; j++) {
Fanta025 0:ed0b4e66d2ad 120 if (bit_value[i*8+j] == 1) {
Fanta025 0:ed0b4e66d2ad 121 b |= (1 << (7-j));
Fanta025 0:ed0b4e66d2ad 122 }
Fanta025 0:ed0b4e66d2ad 123 }
Fanta025 0:ed0b4e66d2ad 124 DHT_data[i]=b;
Fanta025 0:ed0b4e66d2ad 125 }
Fanta025 0:ed0b4e66d2ad 126
Fanta025 0:ed0b4e66d2ad 127 // uncomment to see the checksum error if it exists
Fanta025 0:ed0b4e66d2ad 128 //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]);
Fanta025 0:ed0b4e66d2ad 129 data_valid = DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3];
Fanta025 0:ed0b4e66d2ad 130 if (DHT_data[4] == data_valid) {
Fanta025 0:ed0b4e66d2ad 131 _lastReadTime = currentTime;
Fanta025 0:ed0b4e66d2ad 132 _lastTemperature = CalcTemperature();
Fanta025 0:ed0b4e66d2ad 133 _lastHumidity = CalcHumidity();
Fanta025 0:ed0b4e66d2ad 134
Fanta025 0:ed0b4e66d2ad 135 } else {
Fanta025 0:ed0b4e66d2ad 136 err = ERROR_CHECKSUM;
Fanta025 0:ed0b4e66d2ad 137 }
Fanta025 0:ed0b4e66d2ad 138
Fanta025 0:ed0b4e66d2ad 139 return err;
Fanta025 0:ed0b4e66d2ad 140
Fanta025 0:ed0b4e66d2ad 141 }
Fanta025 0:ed0b4e66d2ad 142
Fanta025 0:ed0b4e66d2ad 143 float DHT::CalcTemperature()
Fanta025 0:ed0b4e66d2ad 144 {
Fanta025 0:ed0b4e66d2ad 145 int v;
Fanta025 0:ed0b4e66d2ad 146
Fanta025 0:ed0b4e66d2ad 147 switch (_DHTtype) {
Fanta025 0:ed0b4e66d2ad 148 case DHT11:
Fanta025 0:ed0b4e66d2ad 149 v = DHT_data[2];
Fanta025 0:ed0b4e66d2ad 150 return float(v);
Fanta025 0:ed0b4e66d2ad 151 case DHT22:
Fanta025 0:ed0b4e66d2ad 152 v = DHT_data[2] & 0x7F;
Fanta025 0:ed0b4e66d2ad 153 v *= 256;
Fanta025 0:ed0b4e66d2ad 154 v += DHT_data[3];
Fanta025 0:ed0b4e66d2ad 155 v /= 10;
Fanta025 0:ed0b4e66d2ad 156 if (DHT_data[2] & 0x80)
Fanta025 0:ed0b4e66d2ad 157 v *= -1;
Fanta025 0:ed0b4e66d2ad 158 return float(v);
Fanta025 0:ed0b4e66d2ad 159 }
Fanta025 0:ed0b4e66d2ad 160 return 0;
Fanta025 0:ed0b4e66d2ad 161 }
Fanta025 0:ed0b4e66d2ad 162
Fanta025 0:ed0b4e66d2ad 163 float DHT::ReadHumidity()
Fanta025 0:ed0b4e66d2ad 164 {
Fanta025 0:ed0b4e66d2ad 165 return _lastHumidity;
Fanta025 0:ed0b4e66d2ad 166 }
Fanta025 0:ed0b4e66d2ad 167
Fanta025 0:ed0b4e66d2ad 168 float DHT::ConvertCelciustoFarenheit(float const celsius)
Fanta025 0:ed0b4e66d2ad 169 {
Fanta025 0:ed0b4e66d2ad 170 return celsius * 9 / 5 + 32;
Fanta025 0:ed0b4e66d2ad 171 }
Fanta025 0:ed0b4e66d2ad 172
Fanta025 0:ed0b4e66d2ad 173 float DHT::ConvertCelciustoKelvin(float const celsius)
Fanta025 0:ed0b4e66d2ad 174 {
Fanta025 0:ed0b4e66d2ad 175 return celsius + 273.15;
Fanta025 0:ed0b4e66d2ad 176 }
Fanta025 0:ed0b4e66d2ad 177
Fanta025 0:ed0b4e66d2ad 178 // dewPoint function NOAA
Fanta025 0:ed0b4e66d2ad 179 // reference: http://wahiduddin.net/calc/density_algorithms.htm
Fanta025 0:ed0b4e66d2ad 180 float DHT::CalcdewPoint(float const celsius, float const humidity)
Fanta025 0:ed0b4e66d2ad 181 {
Fanta025 0:ed0b4e66d2ad 182 float A0= 373.15/(273.15 + celsius);
Fanta025 0:ed0b4e66d2ad 183 float SUM = -7.90298 * (A0-1);
Fanta025 0:ed0b4e66d2ad 184 SUM += 5.02808 * log10(A0);
Fanta025 0:ed0b4e66d2ad 185 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
Fanta025 0:ed0b4e66d2ad 186 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
Fanta025 0:ed0b4e66d2ad 187 SUM += log10(1013.246);
Fanta025 0:ed0b4e66d2ad 188 float VP = pow(10, SUM-3) * humidity;
Fanta025 0:ed0b4e66d2ad 189 float T = log(VP/0.61078); // temp var
Fanta025 0:ed0b4e66d2ad 190 return (241.88 * T) / (17.558-T);
Fanta025 0:ed0b4e66d2ad 191 }
Fanta025 0:ed0b4e66d2ad 192
Fanta025 0:ed0b4e66d2ad 193 // delta max = 0.6544 wrt dewPoint()
Fanta025 0:ed0b4e66d2ad 194 // 5x faster than dewPoint()
Fanta025 0:ed0b4e66d2ad 195 // reference: http://en.wikipedia.org/wiki/Dew_point
Fanta025 0:ed0b4e66d2ad 196 float DHT::CalcdewPointFast(float const celsius, float const humidity)
Fanta025 0:ed0b4e66d2ad 197 {
Fanta025 0:ed0b4e66d2ad 198 float a = 17.271;
Fanta025 0:ed0b4e66d2ad 199 float b = 237.7;
Fanta025 0:ed0b4e66d2ad 200 float temp = (a * celsius) / (b + celsius) + log(humidity/100);
Fanta025 0:ed0b4e66d2ad 201 float Td = (b * temp) / (a - temp);
Fanta025 0:ed0b4e66d2ad 202 return Td;
Fanta025 0:ed0b4e66d2ad 203 }
Fanta025 0:ed0b4e66d2ad 204
Fanta025 0:ed0b4e66d2ad 205 float DHT::ReadTemperature(eScale Scale)
Fanta025 0:ed0b4e66d2ad 206 {
Fanta025 0:ed0b4e66d2ad 207 if (Scale == FARENHEIT)
Fanta025 0:ed0b4e66d2ad 208 return ConvertCelciustoFarenheit(_lastTemperature);
Fanta025 0:ed0b4e66d2ad 209 else if (Scale == KELVIN)
Fanta025 0:ed0b4e66d2ad 210 return ConvertCelciustoKelvin(_lastTemperature);
Fanta025 0:ed0b4e66d2ad 211 else
Fanta025 0:ed0b4e66d2ad 212 return _lastTemperature;
Fanta025 0:ed0b4e66d2ad 213 }
Fanta025 0:ed0b4e66d2ad 214
Fanta025 0:ed0b4e66d2ad 215 float DHT::CalcHumidity()
Fanta025 0:ed0b4e66d2ad 216 {
Fanta025 0:ed0b4e66d2ad 217 int v;
Fanta025 0:ed0b4e66d2ad 218
Fanta025 0:ed0b4e66d2ad 219 switch (_DHTtype) {
Fanta025 0:ed0b4e66d2ad 220 case DHT11:
Fanta025 0:ed0b4e66d2ad 221 v = DHT_data[0];
Fanta025 0:ed0b4e66d2ad 222 return float(v);
Fanta025 0:ed0b4e66d2ad 223 case DHT22:
Fanta025 0:ed0b4e66d2ad 224 v = DHT_data[0];
Fanta025 0:ed0b4e66d2ad 225 v *= 256;
Fanta025 0:ed0b4e66d2ad 226 v += DHT_data[1];
Fanta025 0:ed0b4e66d2ad 227 v /= 10;
Fanta025 0:ed0b4e66d2ad 228 return float(v);
Fanta025 0:ed0b4e66d2ad 229 }
Fanta025 0:ed0b4e66d2ad 230 return 0;
Fanta025 0:ed0b4e66d2ad 231 }
Fanta025 0:ed0b4e66d2ad 232
Fanta025 0:ed0b4e66d2ad 233