ihsan hadi / DHT

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DHT.cpp@0:1a8163abbb7d, 2019-09-16 (annotated)

Committer:
alienbernamaihsan
Date:
Mon Sep 16 10:07:29 2019 +0000
Revision:
0:1a8163abbb7d
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alienbernamaihsan 0:1a8163abbb7d 1 /*
alienbernamaihsan 0:1a8163abbb7d 2 * DHT Library for Digital-output Humidity and Temperature sensors
alienbernamaihsan 0:1a8163abbb7d 3 *
alienbernamaihsan 0:1a8163abbb7d 4 * Works with DHT11, DHT22
alienbernamaihsan 0:1a8163abbb7d 5 * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
alienbernamaihsan 0:1a8163abbb7d 6 * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
alienbernamaihsan 0:1a8163abbb7d 7 * AM2302 , temperature-humidity sensor
alienbernamaihsan 0:1a8163abbb7d 8 * HM2303 , Digital-output humidity and temperature sensor
alienbernamaihsan 0:1a8163abbb7d 9 *
alienbernamaihsan 0:1a8163abbb7d 10 * Copyright (C) Wim De Roeve
alienbernamaihsan 0:1a8163abbb7d 11 * based on DHT22 sensor library by HO WING KIT
alienbernamaihsan 0:1a8163abbb7d 12 * Arduino DHT11 library
alienbernamaihsan 0:1a8163abbb7d 13 *
alienbernamaihsan 0:1a8163abbb7d 14 * Permission is hereby granted, free of charge, to any person obtaining a copy
alienbernamaihsan 0:1a8163abbb7d 15 * of this software and associated documnetation files (the "Software"), to deal
alienbernamaihsan 0:1a8163abbb7d 16 * in the Software without restriction, including without limitation the rights
alienbernamaihsan 0:1a8163abbb7d 17 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
alienbernamaihsan 0:1a8163abbb7d 18 * copies of the Software, and to permit persons to whom the Software is
alienbernamaihsan 0:1a8163abbb7d 19 * furished to do so, subject to the following conditions:
alienbernamaihsan 0:1a8163abbb7d 20 *
alienbernamaihsan 0:1a8163abbb7d 21 * The above copyright notice and this permission notice shall be included in
alienbernamaihsan 0:1a8163abbb7d 22 * all copies or substantial portions of the Software.
alienbernamaihsan 0:1a8163abbb7d 23 *
alienbernamaihsan 0:1a8163abbb7d 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
alienbernamaihsan 0:1a8163abbb7d 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
alienbernamaihsan 0:1a8163abbb7d 26 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
alienbernamaihsan 0:1a8163abbb7d 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
alienbernamaihsan 0:1a8163abbb7d 28 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
alienbernamaihsan 0:1a8163abbb7d 29 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
alienbernamaihsan 0:1a8163abbb7d 30 * THE SOFTWARE.
alienbernamaihsan 0:1a8163abbb7d 31 */
alienbernamaihsan 0:1a8163abbb7d 32
alienbernamaihsan 0:1a8163abbb7d 33 #include "DHT.h"
alienbernamaihsan 0:1a8163abbb7d 34
alienbernamaihsan 0:1a8163abbb7d 35 #define DHT_DATA_BIT_COUNT 40
alienbernamaihsan 0:1a8163abbb7d 36
alienbernamaihsan 0:1a8163abbb7d 37 DHT::DHT(PinName pin, eType DHTtype)
alienbernamaihsan 0:1a8163abbb7d 38 {
alienbernamaihsan 0:1a8163abbb7d 39 _pin = pin;
alienbernamaihsan 0:1a8163abbb7d 40 _DHTtype = DHTtype;
alienbernamaihsan 0:1a8163abbb7d 41 _firsttime = true;
alienbernamaihsan 0:1a8163abbb7d 42 }
alienbernamaihsan 0:1a8163abbb7d 43
alienbernamaihsan 0:1a8163abbb7d 44 DHT::~DHT()
alienbernamaihsan 0:1a8163abbb7d 45 {
alienbernamaihsan 0:1a8163abbb7d 46
alienbernamaihsan 0:1a8163abbb7d 47 }
alienbernamaihsan 0:1a8163abbb7d 48
alienbernamaihsan 0:1a8163abbb7d 49 eError DHT::stall(DigitalInOut &io, int const level, int const max_time)
alienbernamaihsan 0:1a8163abbb7d 50 {
alienbernamaihsan 0:1a8163abbb7d 51 int cnt = 0;
alienbernamaihsan 0:1a8163abbb7d 52 while (level == io) {
alienbernamaihsan 0:1a8163abbb7d 53 if (cnt > max_time) {
alienbernamaihsan 0:1a8163abbb7d 54 return ERROR_NO_PATIENCE;
alienbernamaihsan 0:1a8163abbb7d 55 }
alienbernamaihsan 0:1a8163abbb7d 56 cnt++;
alienbernamaihsan 0:1a8163abbb7d 57 wait_us(1);
alienbernamaihsan 0:1a8163abbb7d 58 }
alienbernamaihsan 0:1a8163abbb7d 59 return ERROR_NONE;
alienbernamaihsan 0:1a8163abbb7d 60 }
alienbernamaihsan 0:1a8163abbb7d 61
alienbernamaihsan 0:1a8163abbb7d 62 eError DHT::readData()
alienbernamaihsan 0:1a8163abbb7d 63 {
alienbernamaihsan 0:1a8163abbb7d 64 uint8_t i = 0, j = 0, b = 0, data_valid = 0;
alienbernamaihsan 0:1a8163abbb7d 65 uint32_t bit_value[DHT_DATA_BIT_COUNT] = {0};
alienbernamaihsan 0:1a8163abbb7d 66
alienbernamaihsan 0:1a8163abbb7d 67 eError err = ERROR_NONE;
alienbernamaihsan 0:1a8163abbb7d 68 time_t currentTime = time(NULL);
alienbernamaihsan 0:1a8163abbb7d 69
alienbernamaihsan 0:1a8163abbb7d 70 DigitalInOut DHT_io(_pin);
alienbernamaihsan 0:1a8163abbb7d 71
alienbernamaihsan 0:1a8163abbb7d 72 // IO must be in hi state to start
alienbernamaihsan 0:1a8163abbb7d 73 if (ERROR_NONE != stall(DHT_io, 0, 250)) {
alienbernamaihsan 0:1a8163abbb7d 74 return BUS_BUSY;
alienbernamaihsan 0:1a8163abbb7d 75 }
alienbernamaihsan 0:1a8163abbb7d 76
alienbernamaihsan 0:1a8163abbb7d 77 // start the transfer
alienbernamaihsan 0:1a8163abbb7d 78 DHT_io.output();
alienbernamaihsan 0:1a8163abbb7d 79 DHT_io = 0;
alienbernamaihsan 0:1a8163abbb7d 80 wait_ms(18);
alienbernamaihsan 0:1a8163abbb7d 81 DHT_io = 1;
alienbernamaihsan 0:1a8163abbb7d 82 wait_us(30);
alienbernamaihsan 0:1a8163abbb7d 83 DHT_io.input();
alienbernamaihsan 0:1a8163abbb7d 84 // wait till the sensor grabs the bus
alienbernamaihsan 0:1a8163abbb7d 85 if (ERROR_NONE != stall(DHT_io, 1, 100)) {
alienbernamaihsan 0:1a8163abbb7d 86 return ERROR_NOT_PRESENT;
alienbernamaihsan 0:1a8163abbb7d 87 }
alienbernamaihsan 0:1a8163abbb7d 88 // sensor should signal low 80us and then hi 80us
alienbernamaihsan 0:1a8163abbb7d 89 if (ERROR_NONE != stall(DHT_io, 0, 100)) {
alienbernamaihsan 0:1a8163abbb7d 90 return ERROR_SYNC_TIMEOUT;
alienbernamaihsan 0:1a8163abbb7d 91 }
alienbernamaihsan 0:1a8163abbb7d 92 if (ERROR_NONE != stall(DHT_io, 1, 100)) {
alienbernamaihsan 0:1a8163abbb7d 93 return ERROR_NO_PATIENCE;
alienbernamaihsan 0:1a8163abbb7d 94 }
alienbernamaihsan 0:1a8163abbb7d 95 // capture the data
alienbernamaihsan 0:1a8163abbb7d 96 for (i = 0; i < 5; i++) {
alienbernamaihsan 0:1a8163abbb7d 97 for (j = 0; j < 8; j++) {
alienbernamaihsan 0:1a8163abbb7d 98 if (ERROR_NONE != stall(DHT_io, 0, 75)) {
alienbernamaihsan 0:1a8163abbb7d 99 return ERROR_DATA_TIMEOUT;
alienbernamaihsan 0:1a8163abbb7d 100 }
alienbernamaihsan 0:1a8163abbb7d 101 // logic 0 is 28us max, 1 is 70us
alienbernamaihsan 0:1a8163abbb7d 102 wait_us(40);
alienbernamaihsan 0:1a8163abbb7d 103 bit_value[i*8+j] = DHT_io;
alienbernamaihsan 0:1a8163abbb7d 104 if (ERROR_NONE != stall(DHT_io, 1, 50)) {
alienbernamaihsan 0:1a8163abbb7d 105 return ERROR_DATA_TIMEOUT;
alienbernamaihsan 0:1a8163abbb7d 106 }
alienbernamaihsan 0:1a8163abbb7d 107 }
alienbernamaihsan 0:1a8163abbb7d 108 }
alienbernamaihsan 0:1a8163abbb7d 109 // store the data
alienbernamaihsan 0:1a8163abbb7d 110 for (i = 0; i < 5; i++) {
alienbernamaihsan 0:1a8163abbb7d 111 b=0;
alienbernamaihsan 0:1a8163abbb7d 112 for (j=0; j<8; j++) {
alienbernamaihsan 0:1a8163abbb7d 113 if (bit_value[i*8+j] == 1) {
alienbernamaihsan 0:1a8163abbb7d 114 b |= (1 << (7-j));
alienbernamaihsan 0:1a8163abbb7d 115 }
alienbernamaihsan 0:1a8163abbb7d 116 }
alienbernamaihsan 0:1a8163abbb7d 117 DHT_data[i]=b;
alienbernamaihsan 0:1a8163abbb7d 118 }
alienbernamaihsan 0:1a8163abbb7d 119
alienbernamaihsan 0:1a8163abbb7d 120 // uncomment to see the checksum error if it exists
alienbernamaihsan 0:1a8163abbb7d 121 //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]);
alienbernamaihsan 0:1a8163abbb7d 122 data_valid = DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3];
alienbernamaihsan 0:1a8163abbb7d 123 if (DHT_data[4] == data_valid) {
alienbernamaihsan 0:1a8163abbb7d 124 _lastReadTime = currentTime;
alienbernamaihsan 0:1a8163abbb7d 125 _lastTemperature = CalcTemperature();
alienbernamaihsan 0:1a8163abbb7d 126 _lastHumidity = CalcHumidity();
alienbernamaihsan 0:1a8163abbb7d 127
alienbernamaihsan 0:1a8163abbb7d 128 } else {
alienbernamaihsan 0:1a8163abbb7d 129 err = ERROR_CHECKSUM;
alienbernamaihsan 0:1a8163abbb7d 130 }
alienbernamaihsan 0:1a8163abbb7d 131
alienbernamaihsan 0:1a8163abbb7d 132 return err;
alienbernamaihsan 0:1a8163abbb7d 133
alienbernamaihsan 0:1a8163abbb7d 134 }
alienbernamaihsan 0:1a8163abbb7d 135
alienbernamaihsan 0:1a8163abbb7d 136 float DHT::CalcTemperature()
alienbernamaihsan 0:1a8163abbb7d 137 {
alienbernamaihsan 0:1a8163abbb7d 138 int v;
alienbernamaihsan 0:1a8163abbb7d 139
alienbernamaihsan 0:1a8163abbb7d 140 switch (_DHTtype) {
alienbernamaihsan 0:1a8163abbb7d 141 case DHT11:
alienbernamaihsan 0:1a8163abbb7d 142 v = DHT_data[2];
alienbernamaihsan 0:1a8163abbb7d 143 return float(v);
alienbernamaihsan 0:1a8163abbb7d 144 case DHT22:
alienbernamaihsan 0:1a8163abbb7d 145 v = DHT_data[2] & 0x7F;
alienbernamaihsan 0:1a8163abbb7d 146 v *= 256;
alienbernamaihsan 0:1a8163abbb7d 147 v += DHT_data[3];
alienbernamaihsan 0:1a8163abbb7d 148 v /= 10;
alienbernamaihsan 0:1a8163abbb7d 149 if (DHT_data[2] & 0x80)
alienbernamaihsan 0:1a8163abbb7d 150 v *= -1;
alienbernamaihsan 0:1a8163abbb7d 151 return float(v);
alienbernamaihsan 0:1a8163abbb7d 152 }
alienbernamaihsan 0:1a8163abbb7d 153 return 0;
alienbernamaihsan 0:1a8163abbb7d 154 }
alienbernamaihsan 0:1a8163abbb7d 155
alienbernamaihsan 0:1a8163abbb7d 156 float DHT::ReadHumidity()
alienbernamaihsan 0:1a8163abbb7d 157 {
alienbernamaihsan 0:1a8163abbb7d 158 return _lastHumidity;
alienbernamaihsan 0:1a8163abbb7d 159 }
alienbernamaihsan 0:1a8163abbb7d 160
alienbernamaihsan 0:1a8163abbb7d 161 float DHT::ConvertCelciustoFarenheit(float const celsius)
alienbernamaihsan 0:1a8163abbb7d 162 {
alienbernamaihsan 0:1a8163abbb7d 163 return celsius * 9 / 5 + 32;
alienbernamaihsan 0:1a8163abbb7d 164 }
alienbernamaihsan 0:1a8163abbb7d 165
alienbernamaihsan 0:1a8163abbb7d 166 float DHT::ConvertCelciustoKelvin(float const celsius)
alienbernamaihsan 0:1a8163abbb7d 167 {
alienbernamaihsan 0:1a8163abbb7d 168 return celsius + 273.15f;
alienbernamaihsan 0:1a8163abbb7d 169 }
alienbernamaihsan 0:1a8163abbb7d 170
alienbernamaihsan 0:1a8163abbb7d 171 // dewPoint function NOAA
alienbernamaihsan 0:1a8163abbb7d 172 // reference: http://wahiduddin.net/calc/density_algorithms.htm
alienbernamaihsan 0:1a8163abbb7d 173 float DHT::CalcdewPoint(float const celsius, float const humidity)
alienbernamaihsan 0:1a8163abbb7d 174 {
alienbernamaihsan 0:1a8163abbb7d 175 float A0= 373.15f/(273.15f + celsius);
alienbernamaihsan 0:1a8163abbb7d 176 float SUM = -7.90298 * (A0-1);
alienbernamaihsan 0:1a8163abbb7d 177 SUM += 5.02808f * log10(A0);
alienbernamaihsan 0:1a8163abbb7d 178 SUM += -1.3816e-7 * (pow(10, (11.344f*(1-1/A0)))-1) ;
alienbernamaihsan 0:1a8163abbb7d 179 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
alienbernamaihsan 0:1a8163abbb7d 180 SUM += log10(1013.246);
alienbernamaihsan 0:1a8163abbb7d 181 float VP = pow(10, SUM-3) * humidity;
alienbernamaihsan 0:1a8163abbb7d 182 float T = log(VP/0.61078f); // temp var
alienbernamaihsan 0:1a8163abbb7d 183 return (241.88f * T) / (17.558f-T);
alienbernamaihsan 0:1a8163abbb7d 184 }
alienbernamaihsan 0:1a8163abbb7d 185
alienbernamaihsan 0:1a8163abbb7d 186 // delta max = 0.6544 wrt dewPoint()
alienbernamaihsan 0:1a8163abbb7d 187 // 5x faster than dewPoint()
alienbernamaihsan 0:1a8163abbb7d 188 // reference: http://en.wikipedia.org/wiki/Dew_point
alienbernamaihsan 0:1a8163abbb7d 189 float DHT::CalcdewPointFast(float const celsius, float const humidity)
alienbernamaihsan 0:1a8163abbb7d 190 {
alienbernamaihsan 0:1a8163abbb7d 191 float a = 17.271;
alienbernamaihsan 0:1a8163abbb7d 192 float b = 237.7;
alienbernamaihsan 0:1a8163abbb7d 193 float temp = (a * celsius) / (b + celsius) + log(humidity/100);
alienbernamaihsan 0:1a8163abbb7d 194 float Td = (b * temp) / (a - temp);
alienbernamaihsan 0:1a8163abbb7d 195 return Td;
alienbernamaihsan 0:1a8163abbb7d 196 }
alienbernamaihsan 0:1a8163abbb7d 197
alienbernamaihsan 0:1a8163abbb7d 198 float DHT::ReadTemperature(eScale Scale)
alienbernamaihsan 0:1a8163abbb7d 199 {
alienbernamaihsan 0:1a8163abbb7d 200 if (Scale == FARENHEIT)
alienbernamaihsan 0:1a8163abbb7d 201 return ConvertCelciustoFarenheit(_lastTemperature);
alienbernamaihsan 0:1a8163abbb7d 202 else if (Scale == KELVIN)
alienbernamaihsan 0:1a8163abbb7d 203 return ConvertCelciustoKelvin(_lastTemperature);
alienbernamaihsan 0:1a8163abbb7d 204 else
alienbernamaihsan 0:1a8163abbb7d 205 return _lastTemperature;
alienbernamaihsan 0:1a8163abbb7d 206 }
alienbernamaihsan 0:1a8163abbb7d 207
alienbernamaihsan 0:1a8163abbb7d 208 float DHT::CalcHumidity()
alienbernamaihsan 0:1a8163abbb7d 209 {
alienbernamaihsan 0:1a8163abbb7d 210 int v;
alienbernamaihsan 0:1a8163abbb7d 211
alienbernamaihsan 0:1a8163abbb7d 212 switch (_DHTtype) {
alienbernamaihsan 0:1a8163abbb7d 213 case DHT11:
alienbernamaihsan 0:1a8163abbb7d 214 v = DHT_data[0];
alienbernamaihsan 0:1a8163abbb7d 215 return float(v);
alienbernamaihsan 0:1a8163abbb7d 216 case DHT22:
alienbernamaihsan 0:1a8163abbb7d 217 v = DHT_data[0];
alienbernamaihsan 0:1a8163abbb7d 218 v *= 256;
alienbernamaihsan 0:1a8163abbb7d 219 v += DHT_data[1];
alienbernamaihsan 0:1a8163abbb7d 220 v /= 10;
alienbernamaihsan 0:1a8163abbb7d 221 return float(v);
alienbernamaihsan 0:1a8163abbb7d 222 }
alienbernamaihsan 0:1a8163abbb7d 223 return 0;
alienbernamaihsan 0:1a8163abbb7d 224 }
alienbernamaihsan 0:1a8163abbb7d 225
alienbernamaihsan 0:1a8163abbb7d 226