Renan Alves / DHT

DHT library modify for DHT11 - DHT22 - AM2302

Dependents:   Navitec-Firmware

Fork of DHT by Components

DHT.cpp@5:00961922037a, 2021-04-05 (annotated)

Committer:
renanbmx123
Date:
Mon Apr 05 01:25:58 2021 +0000
Revision:
5:00961922037a
Parent:
4:0242d8d27c1e 
alter

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Wimpie 0:9b5b3200688f 1 /*
Wimpie 0:9b5b3200688f 2 * DHT Library for Digital-output Humidity and Temperature sensors
Wimpie 0:9b5b3200688f 3 *
Wimpie 0:9b5b3200688f 4 * Works with DHT11, DHT22
Wimpie 0:9b5b3200688f 5 * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
Wimpie 0:9b5b3200688f 6 * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
Wimpie 0:9b5b3200688f 7 * AM2302 , temperature-humidity sensor
Wimpie 0:9b5b3200688f 8 * HM2303 , Digital-output humidity and temperature sensor
Wimpie 0:9b5b3200688f 9 *
Wimpie 0:9b5b3200688f 10 * Copyright (C) Wim De Roeve
Wimpie 0:9b5b3200688f 11 * based on DHT22 sensor library by HO WING KIT
sam_grove 2:df22ddf10d75 12 * Arduino DHT11 library
Wimpie 0:9b5b3200688f 13 *
Wimpie 0:9b5b3200688f 14 * Permission is hereby granted, free of charge, to any person obtaining a copy
Wimpie 0:9b5b3200688f 15 * of this software and associated documnetation files (the "Software"), to deal
Wimpie 0:9b5b3200688f 16 * in the Software without restriction, including without limitation the rights
Wimpie 0:9b5b3200688f 17 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
Wimpie 0:9b5b3200688f 18 * copies of the Software, and to permit persons to whom the Software is
Wimpie 0:9b5b3200688f 19 * furished to do so, subject to the following conditions:
Wimpie 0:9b5b3200688f 20 *
Wimpie 0:9b5b3200688f 21 * The above copyright notice and this permission notice shall be included in
Wimpie 0:9b5b3200688f 22 * all copies or substantial portions of the Software.
Wimpie 0:9b5b3200688f 23 *
Wimpie 0:9b5b3200688f 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Wimpie 0:9b5b3200688f 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Wimpie 0:9b5b3200688f 26 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
Wimpie 0:9b5b3200688f 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Wimpie 0:9b5b3200688f 28 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
Wimpie 0:9b5b3200688f 29 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
Wimpie 0:9b5b3200688f 30 * THE SOFTWARE.
Wimpie 0:9b5b3200688f 31 */
renanbmx123 5:00961922037a 32
Wimpie 0:9b5b3200688f 33
Wimpie 0:9b5b3200688f 34 #include "DHT.h"
Wimpie 0:9b5b3200688f 35
sam_grove 2:df22ddf10d75 36 #define DHT_DATA_BIT_COUNT 40
Wimpie 0:9b5b3200688f 37
sam_grove 2:df22ddf10d75 38 DHT::DHT(PinName pin, eType DHTtype)
sam_grove 2:df22ddf10d75 39 {
Wimpie 0:9b5b3200688f 40 _pin = pin;
Wimpie 0:9b5b3200688f 41 _DHTtype = DHTtype;
sam_grove 2:df22ddf10d75 42 _firsttime = true;
sam_grove 2:df22ddf10d75 43 }
sam_grove 2:df22ddf10d75 44
sam_grove 2:df22ddf10d75 45 DHT::~DHT()
sam_grove 2:df22ddf10d75 46 {
sam_grove 2:df22ddf10d75 47
Wimpie 0:9b5b3200688f 48 }
Wimpie 0:9b5b3200688f 49
sam_grove 2:df22ddf10d75 50 eError DHT::stall(DigitalInOut &io, int const level, int const max_time)
sam_grove 2:df22ddf10d75 51 {
sam_grove 2:df22ddf10d75 52 int cnt = 0;
sam_grove 2:df22ddf10d75 53 while (level == io) {
sam_grove 2:df22ddf10d75 54 if (cnt > max_time) {
renanbmx123 3:24682a533803 55
sam_grove 2:df22ddf10d75 56 return ERROR_NO_PATIENCE;
sam_grove 2:df22ddf10d75 57 }
sam_grove 2:df22ddf10d75 58 cnt++;
sam_grove 2:df22ddf10d75 59 wait_us(1);
sam_grove 2:df22ddf10d75 60 }
sam_grove 2:df22ddf10d75 61 return ERROR_NONE;
Wimpie 0:9b5b3200688f 62 }
Wimpie 0:9b5b3200688f 63
sam_grove 2:df22ddf10d75 64 eError DHT::readData()
sam_grove 2:df22ddf10d75 65 {
sam_grove 2:df22ddf10d75 66 uint8_t i = 0, j = 0, b = 0, data_valid = 0;
sam_grove 2:df22ddf10d75 67 uint32_t bit_value[DHT_DATA_BIT_COUNT] = {0};
Wimpie 0:9b5b3200688f 68
Wimpie 0:9b5b3200688f 69 eError err = ERROR_NONE;
Wimpie 0:9b5b3200688f 70 time_t currentTime = time(NULL);
Wimpie 0:9b5b3200688f 71
Wimpie 0:9b5b3200688f 72 DigitalInOut DHT_io(_pin);
Wimpie 0:9b5b3200688f 73
sam_grove 2:df22ddf10d75 74 // IO must be in hi state to start
sam_grove 2:df22ddf10d75 75 if (ERROR_NONE != stall(DHT_io, 0, 250)) {
sam_grove 2:df22ddf10d75 76 return BUS_BUSY;
Wimpie 0:9b5b3200688f 77 }
Wimpie 0:9b5b3200688f 78
sam_grove 2:df22ddf10d75 79 // start the transfer
Wimpie 0:9b5b3200688f 80 DHT_io.output();
Wimpie 0:9b5b3200688f 81 DHT_io = 0;
sam_grove 2:df22ddf10d75 82 // only 500uS for DHT22 but 18ms for DHT11
renanbmx123 4:0242d8d27c1e 83 (_DHTtype == 11) ? ThisThread::sleep_for(chrono::milliseconds(18))/*wait_ms(18)*/ : wait_us(500);
Wimpie 0:9b5b3200688f 84 DHT_io = 1;
sam_grove 2:df22ddf10d75 85 wait_us(30);
Wimpie 0:9b5b3200688f 86 DHT_io.input();
renanbmx123 3:24682a533803 87
sam_grove 2:df22ddf10d75 88 // wait till the sensor grabs the bus
sam_grove 2:df22ddf10d75 89 if (ERROR_NONE != stall(DHT_io, 1, 40)) {
sam_grove 2:df22ddf10d75 90 return ERROR_NOT_PRESENT;
Wimpie 0:9b5b3200688f 91 }
sam_grove 2:df22ddf10d75 92 // sensor should signal low 80us and then hi 80us
sam_grove 2:df22ddf10d75 93 if (ERROR_NONE != stall(DHT_io, 0, 100)) {
sam_grove 2:df22ddf10d75 94 return ERROR_SYNC_TIMEOUT;
sam_grove 2:df22ddf10d75 95 }
sam_grove 2:df22ddf10d75 96 if (ERROR_NONE != stall(DHT_io, 1, 100)) {
sam_grove 2:df22ddf10d75 97 return ERROR_NO_PATIENCE;
sam_grove 2:df22ddf10d75 98 }
sam_grove 2:df22ddf10d75 99 // capture the data
Wimpie 0:9b5b3200688f 100 for (i = 0; i < 5; i++) {
Wimpie 0:9b5b3200688f 101 for (j = 0; j < 8; j++) {
sam_grove 2:df22ddf10d75 102 if (ERROR_NONE != stall(DHT_io, 0, 75)) {
sam_grove 2:df22ddf10d75 103 return ERROR_DATA_TIMEOUT;
sam_grove 2:df22ddf10d75 104 }
sam_grove 2:df22ddf10d75 105 // logic 0 is 28us max, 1 is 70us
Wimpie 0:9b5b3200688f 106 wait_us(40);
sam_grove 2:df22ddf10d75 107 bit_value[i*8+j] = DHT_io;
sam_grove 2:df22ddf10d75 108 if (ERROR_NONE != stall(DHT_io, 1, 50)) {
sam_grove 2:df22ddf10d75 109 return ERROR_DATA_TIMEOUT;
Wimpie 0:9b5b3200688f 110 }
Wimpie 0:9b5b3200688f 111 }
Wimpie 0:9b5b3200688f 112 }
sam_grove 2:df22ddf10d75 113 // store the data
Wimpie 0:9b5b3200688f 114 for (i = 0; i < 5; i++) {
Wimpie 0:9b5b3200688f 115 b=0;
Wimpie 0:9b5b3200688f 116 for (j=0; j<8; j++) {
sam_grove 2:df22ddf10d75 117 if (bit_value[i*8+j] == 1) {
sam_grove 2:df22ddf10d75 118 b |= (1 << (7-j));
Wimpie 0:9b5b3200688f 119 }
Wimpie 0:9b5b3200688f 120 }
Wimpie 0:9b5b3200688f 121 DHT_data[i]=b;
Wimpie 0:9b5b3200688f 122 }
Wimpie 0:9b5b3200688f 123
sam_grove 2:df22ddf10d75 124 // uncomment to see the checksum error if it exists
sam_grove 2:df22ddf10d75 125 //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]);
sam_grove 2:df22ddf10d75 126 data_valid = DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3];
sam_grove 2:df22ddf10d75 127 if (DHT_data[4] == data_valid) {
Wimpie 0:9b5b3200688f 128 _lastReadTime = currentTime;
sam_grove 2:df22ddf10d75 129 _lastTemperature = CalcTemperature();
sam_grove 2:df22ddf10d75 130 _lastHumidity = CalcHumidity();
Wimpie 0:9b5b3200688f 131
Wimpie 0:9b5b3200688f 132 } else {
Wimpie 0:9b5b3200688f 133 err = ERROR_CHECKSUM;
Wimpie 0:9b5b3200688f 134 }
Wimpie 0:9b5b3200688f 135
Wimpie 0:9b5b3200688f 136 return err;
Wimpie 0:9b5b3200688f 137
Wimpie 0:9b5b3200688f 138 }
Wimpie 0:9b5b3200688f 139
sam_grove 2:df22ddf10d75 140 float DHT::CalcTemperature()
sam_grove 2:df22ddf10d75 141 {
Wimpie 0:9b5b3200688f 142 int v;
Wimpie 0:9b5b3200688f 143
Wimpie 0:9b5b3200688f 144 switch (_DHTtype) {
Wimpie 0:9b5b3200688f 145 case DHT11:
Wimpie 0:9b5b3200688f 146 v = DHT_data[2];
Wimpie 0:9b5b3200688f 147 return float(v);
Wimpie 0:9b5b3200688f 148 case DHT22:
Wimpie 0:9b5b3200688f 149 v = DHT_data[2] & 0x7F;
Wimpie 0:9b5b3200688f 150 v *= 256;
Wimpie 0:9b5b3200688f 151 v += DHT_data[3];
Wimpie 0:9b5b3200688f 152 v /= 10;
Wimpie 0:9b5b3200688f 153 if (DHT_data[2] & 0x80)
Wimpie 0:9b5b3200688f 154 v *= -1;
Wimpie 0:9b5b3200688f 155 return float(v);
Wimpie 0:9b5b3200688f 156 }
Wimpie 0:9b5b3200688f 157 return 0;
Wimpie 0:9b5b3200688f 158 }
Wimpie 0:9b5b3200688f 159
sam_grove 2:df22ddf10d75 160 float DHT::ReadHumidity()
sam_grove 2:df22ddf10d75 161 {
Wimpie 0:9b5b3200688f 162 return _lastHumidity;
Wimpie 0:9b5b3200688f 163 }
Wimpie 0:9b5b3200688f 164
sam_grove 2:df22ddf10d75 165 float DHT::ConvertCelciustoFarenheit(float const celsius)
sam_grove 2:df22ddf10d75 166 {
Wimpie 0:9b5b3200688f 167 return celsius * 9 / 5 + 32;
Wimpie 0:9b5b3200688f 168 }
Wimpie 0:9b5b3200688f 169
sam_grove 2:df22ddf10d75 170 float DHT::ConvertCelciustoKelvin(float const celsius)
sam_grove 2:df22ddf10d75 171 {
Wimpie 0:9b5b3200688f 172 return celsius + 273.15;
Wimpie 0:9b5b3200688f 173 }
Wimpie 0:9b5b3200688f 174
Wimpie 0:9b5b3200688f 175 // dewPoint function NOAA
Wimpie 0:9b5b3200688f 176 // reference: http://wahiduddin.net/calc/density_algorithms.htm
sam_grove 2:df22ddf10d75 177 float DHT::CalcdewPoint(float const celsius, float const humidity)
sam_grove 2:df22ddf10d75 178 {
Wimpie 0:9b5b3200688f 179 float A0= 373.15/(273.15 + celsius);
Wimpie 0:9b5b3200688f 180 float SUM = -7.90298 * (A0-1);
Wimpie 0:9b5b3200688f 181 SUM += 5.02808 * log10(A0);
Wimpie 0:9b5b3200688f 182 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
Wimpie 0:9b5b3200688f 183 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
Wimpie 0:9b5b3200688f 184 SUM += log10(1013.246);
Wimpie 0:9b5b3200688f 185 float VP = pow(10, SUM-3) * humidity;
Wimpie 0:9b5b3200688f 186 float T = log(VP/0.61078); // temp var
Wimpie 0:9b5b3200688f 187 return (241.88 * T) / (17.558-T);
Wimpie 0:9b5b3200688f 188 }
Wimpie 0:9b5b3200688f 189
Wimpie 0:9b5b3200688f 190 // delta max = 0.6544 wrt dewPoint()
Wimpie 0:9b5b3200688f 191 // 5x faster than dewPoint()
Wimpie 0:9b5b3200688f 192 // reference: http://en.wikipedia.org/wiki/Dew_point
sam_grove 2:df22ddf10d75 193 float DHT::CalcdewPointFast(float const celsius, float const humidity)
Wimpie 0:9b5b3200688f 194 {
sam_grove 2:df22ddf10d75 195 float a = 17.271;
sam_grove 2:df22ddf10d75 196 float b = 237.7;
sam_grove 2:df22ddf10d75 197 float temp = (a * celsius) / (b + celsius) + log(humidity/100);
sam_grove 2:df22ddf10d75 198 float Td = (b * temp) / (a - temp);
sam_grove 2:df22ddf10d75 199 return Td;
Wimpie 0:9b5b3200688f 200 }
Wimpie 0:9b5b3200688f 201
sam_grove 2:df22ddf10d75 202 float DHT::ReadTemperature(eScale Scale)
sam_grove 2:df22ddf10d75 203 {
Wimpie 0:9b5b3200688f 204 if (Scale == FARENHEIT)
Wimpie 0:9b5b3200688f 205 return ConvertCelciustoFarenheit(_lastTemperature);
Wimpie 0:9b5b3200688f 206 else if (Scale == KELVIN)
Wimpie 0:9b5b3200688f 207 return ConvertCelciustoKelvin(_lastTemperature);
Wimpie 0:9b5b3200688f 208 else
Wimpie 0:9b5b3200688f 209 return _lastTemperature;
Wimpie 0:9b5b3200688f 210 }
Wimpie 0:9b5b3200688f 211
sam_grove 2:df22ddf10d75 212 float DHT::CalcHumidity()
sam_grove 2:df22ddf10d75 213 {
Wimpie 0:9b5b3200688f 214 int v;
Wimpie 0:9b5b3200688f 215
Wimpie 0:9b5b3200688f 216 switch (_DHTtype) {
Wimpie 0:9b5b3200688f 217 case DHT11:
Wimpie 0:9b5b3200688f 218 v = DHT_data[0];
Wimpie 0:9b5b3200688f 219 return float(v);
Wimpie 0:9b5b3200688f 220 case DHT22:
Wimpie 0:9b5b3200688f 221 v = DHT_data[0];
Wimpie 0:9b5b3200688f 222 v *= 256;
Wimpie 0:9b5b3200688f 223 v += DHT_data[1];
Wimpie 0:9b5b3200688f 224 v /= 10;
Wimpie 0:9b5b3200688f 225 return float(v);
Wimpie 0:9b5b3200688f 226 }
Wimpie 0:9b5b3200688f 227 return 0;
Wimpie 0:9b5b3200688f 228 }
Wimpie 0:9b5b3200688f 229
Wimpie 0:9b5b3200688f 230