Bernard Arnault / Mbed 2 deprecated mbed-os-tp_sigfox

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   mbed

DHT.cpp@0:2d8f1aed9d70, 2020-07-06 (annotated)

Committer:
bernard_arnault
Date:
Mon Jul 06 13:59:08 2020 +0000
Revision:
0:2d8f1aed9d70
First draft NUCELO-LK32KC and DHT11

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bernard_arnault 0:2d8f1aed9d70 1 /*
bernard_arnault 0:2d8f1aed9d70 2 * DHT Library for Digital-output Humidity and Temperature sensors
bernard_arnault 0:2d8f1aed9d70 3 *
bernard_arnault 0:2d8f1aed9d70 4 * Works with DHT11, DHT22
bernard_arnault 0:2d8f1aed9d70 5 * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
bernard_arnault 0:2d8f1aed9d70 6 * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
bernard_arnault 0:2d8f1aed9d70 7 * AM2302 , temperature-humidity sensor
bernard_arnault 0:2d8f1aed9d70 8 * HM2303 , Digital-output humidity and temperature sensor
bernard_arnault 0:2d8f1aed9d70 9 *
bernard_arnault 0:2d8f1aed9d70 10 * Copyright (C) Wim De Roeve
bernard_arnault 0:2d8f1aed9d70 11 * based on DHT22 sensor library by HO WING KIT
bernard_arnault 0:2d8f1aed9d70 12 * Arduino DHT11 library
bernard_arnault 0:2d8f1aed9d70 13 *
bernard_arnault 0:2d8f1aed9d70 14 * Permission is hereby granted, free of charge, to any person obtaining a copy
bernard_arnault 0:2d8f1aed9d70 15 * of this software and associated documnetation files (the "Software"), to deal
bernard_arnault 0:2d8f1aed9d70 16 * in the Software without restriction, including without limitation the rights
bernard_arnault 0:2d8f1aed9d70 17 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
bernard_arnault 0:2d8f1aed9d70 18 * copies of the Software, and to permit persons to whom the Software is
bernard_arnault 0:2d8f1aed9d70 19 * furished to do so, subject to the following conditions:
bernard_arnault 0:2d8f1aed9d70 20 *
bernard_arnault 0:2d8f1aed9d70 21 * The above copyright notice and this permission notice shall be included in
bernard_arnault 0:2d8f1aed9d70 22 * all copies or substantial portions of the Software.
bernard_arnault 0:2d8f1aed9d70 23 *
bernard_arnault 0:2d8f1aed9d70 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
bernard_arnault 0:2d8f1aed9d70 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
bernard_arnault 0:2d8f1aed9d70 26 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
bernard_arnault 0:2d8f1aed9d70 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
bernard_arnault 0:2d8f1aed9d70 28 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
bernard_arnault 0:2d8f1aed9d70 29 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
bernard_arnault 0:2d8f1aed9d70 30 * THE SOFTWARE.
bernard_arnault 0:2d8f1aed9d70 31 */
bernard_arnault 0:2d8f1aed9d70 32
bernard_arnault 0:2d8f1aed9d70 33 #include "DHT.h"
bernard_arnault 0:2d8f1aed9d70 34
bernard_arnault 0:2d8f1aed9d70 35 #define DHT_DATA_BIT_COUNT 41
bernard_arnault 0:2d8f1aed9d70 36
bernard_arnault 0:2d8f1aed9d70 37 DHT::DHT(PinName pin,int DHTtype) {
bernard_arnault 0:2d8f1aed9d70 38 _pin = pin;
bernard_arnault 0:2d8f1aed9d70 39 _DHTtype = DHTtype;
bernard_arnault 0:2d8f1aed9d70 40 _firsttime=true;
bernard_arnault 0:2d8f1aed9d70 41 }
bernard_arnault 0:2d8f1aed9d70 42
bernard_arnault 0:2d8f1aed9d70 43 DHT::~DHT() {
bernard_arnault 0:2d8f1aed9d70 44 }
bernard_arnault 0:2d8f1aed9d70 45
bernard_arnault 0:2d8f1aed9d70 46 int DHT::readData() {
bernard_arnault 0:2d8f1aed9d70 47 int i, j, retryCount,b;
bernard_arnault 0:2d8f1aed9d70 48 unsigned int bitTimes[DHT_DATA_BIT_COUNT];
bernard_arnault 0:2d8f1aed9d70 49
bernard_arnault 0:2d8f1aed9d70 50 eError err = ERROR_NONE;
bernard_arnault 0:2d8f1aed9d70 51 time_t currentTime = time(NULL);
bernard_arnault 0:2d8f1aed9d70 52
bernard_arnault 0:2d8f1aed9d70 53 DigitalInOut DHT_io(_pin);
bernard_arnault 0:2d8f1aed9d70 54
bernard_arnault 0:2d8f1aed9d70 55 for (i = 0; i < DHT_DATA_BIT_COUNT; i++) {
bernard_arnault 0:2d8f1aed9d70 56 bitTimes[i] = 0;
bernard_arnault 0:2d8f1aed9d70 57 }
bernard_arnault 0:2d8f1aed9d70 58
bernard_arnault 0:2d8f1aed9d70 59 if (!_firsttime) {
bernard_arnault 0:2d8f1aed9d70 60 if (int(currentTime - _lastReadTime) < 2) {
bernard_arnault 0:2d8f1aed9d70 61 err = ERROR_NO_PATIENCE;
bernard_arnault 0:2d8f1aed9d70 62 return err;
bernard_arnault 0:2d8f1aed9d70 63 }
bernard_arnault 0:2d8f1aed9d70 64 } else {
bernard_arnault 0:2d8f1aed9d70 65 _firsttime=false;
bernard_arnault 0:2d8f1aed9d70 66 _lastReadTime=currentTime;
bernard_arnault 0:2d8f1aed9d70 67 }
bernard_arnault 0:2d8f1aed9d70 68 retryCount = 0;
bernard_arnault 0:2d8f1aed9d70 69
bernard_arnault 0:2d8f1aed9d70 70 do {
bernard_arnault 0:2d8f1aed9d70 71 if (retryCount > 125) {
bernard_arnault 0:2d8f1aed9d70 72 err = BUS_BUSY;
bernard_arnault 0:2d8f1aed9d70 73 return err;
bernard_arnault 0:2d8f1aed9d70 74 }
bernard_arnault 0:2d8f1aed9d70 75 retryCount ++;
bernard_arnault 0:2d8f1aed9d70 76 wait_us(2);
bernard_arnault 0:2d8f1aed9d70 77 } while ((DHT_io==0));
bernard_arnault 0:2d8f1aed9d70 78
bernard_arnault 0:2d8f1aed9d70 79
bernard_arnault 0:2d8f1aed9d70 80 DHT_io.output();
bernard_arnault 0:2d8f1aed9d70 81 DHT_io = 0;
bernard_arnault 0:2d8f1aed9d70 82 wait_ms(18);
bernard_arnault 0:2d8f1aed9d70 83 DHT_io = 1;
bernard_arnault 0:2d8f1aed9d70 84 wait_us(40);
bernard_arnault 0:2d8f1aed9d70 85 DHT_io.input();
bernard_arnault 0:2d8f1aed9d70 86
bernard_arnault 0:2d8f1aed9d70 87 retryCount = 0;
bernard_arnault 0:2d8f1aed9d70 88 do {
bernard_arnault 0:2d8f1aed9d70 89 if (retryCount > 40) {
bernard_arnault 0:2d8f1aed9d70 90 err = ERROR_NOT_PRESENT;
bernard_arnault 0:2d8f1aed9d70 91 return err;
bernard_arnault 0:2d8f1aed9d70 92 }
bernard_arnault 0:2d8f1aed9d70 93 retryCount++;
bernard_arnault 0:2d8f1aed9d70 94 wait_us(1);
bernard_arnault 0:2d8f1aed9d70 95 } while ((DHT_io==1));
bernard_arnault 0:2d8f1aed9d70 96
bernard_arnault 0:2d8f1aed9d70 97 if (err != ERROR_NONE) {
bernard_arnault 0:2d8f1aed9d70 98 return err;
bernard_arnault 0:2d8f1aed9d70 99 }
bernard_arnault 0:2d8f1aed9d70 100
bernard_arnault 0:2d8f1aed9d70 101 wait_us(80);
bernard_arnault 0:2d8f1aed9d70 102
bernard_arnault 0:2d8f1aed9d70 103 for (i = 0; i < 5; i++) {
bernard_arnault 0:2d8f1aed9d70 104 for (j = 0; j < 8; j++) {
bernard_arnault 0:2d8f1aed9d70 105
bernard_arnault 0:2d8f1aed9d70 106 retryCount = 0;
bernard_arnault 0:2d8f1aed9d70 107 do {
bernard_arnault 0:2d8f1aed9d70 108 if (retryCount > 75) {
bernard_arnault 0:2d8f1aed9d70 109 err = ERROR_DATA_TIMEOUT;
bernard_arnault 0:2d8f1aed9d70 110 return err;
bernard_arnault 0:2d8f1aed9d70 111 }
bernard_arnault 0:2d8f1aed9d70 112 retryCount++;
bernard_arnault 0:2d8f1aed9d70 113 wait_us(1);
bernard_arnault 0:2d8f1aed9d70 114 } while (DHT_io == 0);
bernard_arnault 0:2d8f1aed9d70 115 wait_us(40);
bernard_arnault 0:2d8f1aed9d70 116 bitTimes[i*8+j]=DHT_io;
bernard_arnault 0:2d8f1aed9d70 117
bernard_arnault 0:2d8f1aed9d70 118 int count = 0;
bernard_arnault 0:2d8f1aed9d70 119 while (DHT_io == 1 && count < 100) {
bernard_arnault 0:2d8f1aed9d70 120 wait_us(1);
bernard_arnault 0:2d8f1aed9d70 121 count++;
bernard_arnault 0:2d8f1aed9d70 122 }
bernard_arnault 0:2d8f1aed9d70 123 }
bernard_arnault 0:2d8f1aed9d70 124 }
bernard_arnault 0:2d8f1aed9d70 125 DHT_io.output();
bernard_arnault 0:2d8f1aed9d70 126 DHT_io = 1;
bernard_arnault 0:2d8f1aed9d70 127 for (i = 0; i < 5; i++) {
bernard_arnault 0:2d8f1aed9d70 128 b=0;
bernard_arnault 0:2d8f1aed9d70 129 for (j=0; j<8; j++) {
bernard_arnault 0:2d8f1aed9d70 130 if (bitTimes[i*8+j+1] > 0) {
bernard_arnault 0:2d8f1aed9d70 131 b |= ( 1 << (7-j));
bernard_arnault 0:2d8f1aed9d70 132 }
bernard_arnault 0:2d8f1aed9d70 133 }
bernard_arnault 0:2d8f1aed9d70 134 DHT_data[i]=b;
bernard_arnault 0:2d8f1aed9d70 135 }
bernard_arnault 0:2d8f1aed9d70 136
bernard_arnault 0:2d8f1aed9d70 137 if (DHT_data[4] == ((DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3]) & 0xFF)) {
bernard_arnault 0:2d8f1aed9d70 138 _lastReadTime = currentTime;
bernard_arnault 0:2d8f1aed9d70 139 _lastTemperature=CalcTemperature();
bernard_arnault 0:2d8f1aed9d70 140 _lastHumidity=CalcHumidity();
bernard_arnault 0:2d8f1aed9d70 141
bernard_arnault 0:2d8f1aed9d70 142 } else {
bernard_arnault 0:2d8f1aed9d70 143 err = ERROR_CHECKSUM;
bernard_arnault 0:2d8f1aed9d70 144 }
bernard_arnault 0:2d8f1aed9d70 145
bernard_arnault 0:2d8f1aed9d70 146 return err;
bernard_arnault 0:2d8f1aed9d70 147
bernard_arnault 0:2d8f1aed9d70 148 }
bernard_arnault 0:2d8f1aed9d70 149
bernard_arnault 0:2d8f1aed9d70 150 float DHT::CalcTemperature() {
bernard_arnault 0:2d8f1aed9d70 151 int v;
bernard_arnault 0:2d8f1aed9d70 152
bernard_arnault 0:2d8f1aed9d70 153 switch (_DHTtype) {
bernard_arnault 0:2d8f1aed9d70 154 case DHT11:
bernard_arnault 0:2d8f1aed9d70 155 v = DHT_data[2];
bernard_arnault 0:2d8f1aed9d70 156 return float(v);
bernard_arnault 0:2d8f1aed9d70 157 case DHT22:
bernard_arnault 0:2d8f1aed9d70 158 v = DHT_data[2] & 0x7F;
bernard_arnault 0:2d8f1aed9d70 159 v *= 256;
bernard_arnault 0:2d8f1aed9d70 160 v += DHT_data[3];
bernard_arnault 0:2d8f1aed9d70 161 v /= 10;
bernard_arnault 0:2d8f1aed9d70 162 if (DHT_data[2] & 0x80)
bernard_arnault 0:2d8f1aed9d70 163 v *= -1;
bernard_arnault 0:2d8f1aed9d70 164 return float(v);
bernard_arnault 0:2d8f1aed9d70 165 }
bernard_arnault 0:2d8f1aed9d70 166 return 0;
bernard_arnault 0:2d8f1aed9d70 167 }
bernard_arnault 0:2d8f1aed9d70 168
bernard_arnault 0:2d8f1aed9d70 169 float DHT::ReadHumidity() {
bernard_arnault 0:2d8f1aed9d70 170 return _lastHumidity;
bernard_arnault 0:2d8f1aed9d70 171 }
bernard_arnault 0:2d8f1aed9d70 172
bernard_arnault 0:2d8f1aed9d70 173 float DHT::ConvertCelciustoFarenheit(float celsius) {
bernard_arnault 0:2d8f1aed9d70 174 return celsius * 9 / 5 + 32;
bernard_arnault 0:2d8f1aed9d70 175 }
bernard_arnault 0:2d8f1aed9d70 176
bernard_arnault 0:2d8f1aed9d70 177 float DHT::ConvertCelciustoKelvin(float celsius) {
bernard_arnault 0:2d8f1aed9d70 178 return celsius + 273.15;
bernard_arnault 0:2d8f1aed9d70 179 }
bernard_arnault 0:2d8f1aed9d70 180
bernard_arnault 0:2d8f1aed9d70 181 // dewPoint function NOAA
bernard_arnault 0:2d8f1aed9d70 182 // reference: http://wahiduddin.net/calc/density_algorithms.htm
bernard_arnault 0:2d8f1aed9d70 183 float DHT::CalcdewPoint(float celsius, float humidity) {
bernard_arnault 0:2d8f1aed9d70 184 float A0= 373.15/(273.15 + celsius);
bernard_arnault 0:2d8f1aed9d70 185 float SUM = -7.90298 * (A0-1);
bernard_arnault 0:2d8f1aed9d70 186 SUM += 5.02808 * log10(A0);
bernard_arnault 0:2d8f1aed9d70 187 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
bernard_arnault 0:2d8f1aed9d70 188 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
bernard_arnault 0:2d8f1aed9d70 189 SUM += log10(1013.246);
bernard_arnault 0:2d8f1aed9d70 190 float VP = pow(10, SUM-3) * humidity;
bernard_arnault 0:2d8f1aed9d70 191 float T = log(VP/0.61078); // temp var
bernard_arnault 0:2d8f1aed9d70 192 return (241.88 * T) / (17.558-T);
bernard_arnault 0:2d8f1aed9d70 193 }
bernard_arnault 0:2d8f1aed9d70 194
bernard_arnault 0:2d8f1aed9d70 195 // delta max = 0.6544 wrt dewPoint()
bernard_arnault 0:2d8f1aed9d70 196 // 5x faster than dewPoint()
bernard_arnault 0:2d8f1aed9d70 197 // reference: http://en.wikipedia.org/wiki/Dew_point
bernard_arnault 0:2d8f1aed9d70 198 float DHT::CalcdewPointFast(float celsius, float humidity)
bernard_arnault 0:2d8f1aed9d70 199 {
bernard_arnault 0:2d8f1aed9d70 200 float a = 17.271;
bernard_arnault 0:2d8f1aed9d70 201 float b = 237.7;
bernard_arnault 0:2d8f1aed9d70 202 float temp = (a * celsius) / (b + celsius) + log(humidity/100);
bernard_arnault 0:2d8f1aed9d70 203 float Td = (b * temp) / (a - temp);
bernard_arnault 0:2d8f1aed9d70 204 return Td;
bernard_arnault 0:2d8f1aed9d70 205 }
bernard_arnault 0:2d8f1aed9d70 206
bernard_arnault 0:2d8f1aed9d70 207 float DHT::ReadTemperature(eScale Scale) {
bernard_arnault 0:2d8f1aed9d70 208 if (Scale == FARENHEIT)
bernard_arnault 0:2d8f1aed9d70 209 return ConvertCelciustoFarenheit(_lastTemperature);
bernard_arnault 0:2d8f1aed9d70 210 else if (Scale == KELVIN)
bernard_arnault 0:2d8f1aed9d70 211 return ConvertCelciustoKelvin(_lastTemperature);
bernard_arnault 0:2d8f1aed9d70 212 else
bernard_arnault 0:2d8f1aed9d70 213 return _lastTemperature;
bernard_arnault 0:2d8f1aed9d70 214 }
bernard_arnault 0:2d8f1aed9d70 215
bernard_arnault 0:2d8f1aed9d70 216 float DHT::CalcHumidity() {
bernard_arnault 0:2d8f1aed9d70 217 int v;
bernard_arnault 0:2d8f1aed9d70 218
bernard_arnault 0:2d8f1aed9d70 219 switch (_DHTtype) {
bernard_arnault 0:2d8f1aed9d70 220 case DHT11:
bernard_arnault 0:2d8f1aed9d70 221 v = DHT_data[0];
bernard_arnault 0:2d8f1aed9d70 222 return float(v);
bernard_arnault 0:2d8f1aed9d70 223 case DHT22:
bernard_arnault 0:2d8f1aed9d70 224 v = DHT_data[0];
bernard_arnault 0:2d8f1aed9d70 225 v *= 256;
bernard_arnault 0:2d8f1aed9d70 226 v += DHT_data[1];
bernard_arnault 0:2d8f1aed9d70 227 v /= 10;
bernard_arnault 0:2d8f1aed9d70 228 return float(v);
bernard_arnault 0:2d8f1aed9d70 229 }
bernard_arnault 0:2d8f1aed9d70 230 return 0;
bernard_arnault 0:2d8f1aed9d70 231 }