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SEN11301P/DHT.cpp@4:5213bee8158e, 2014-04-14 (annotated)
- Committer:
- redplam
- Date:
- Mon Apr 14 02:15:32 2014 +0000
- Revision:
- 4:5213bee8158e
myproject;
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
redplam | 4:5213bee8158e | 1 | |
redplam | 4:5213bee8158e | 2 | #include "DHT.h" |
redplam | 4:5213bee8158e | 3 | |
redplam | 4:5213bee8158e | 4 | #define DHT_DATA_BIT_COUNT 40 |
redplam | 4:5213bee8158e | 5 | |
redplam | 4:5213bee8158e | 6 | DHT::DHT(PinName pin,int DHTtype) { |
redplam | 4:5213bee8158e | 7 | _pin = pin; |
redplam | 4:5213bee8158e | 8 | _DHTtype = DHTtype; |
redplam | 4:5213bee8158e | 9 | _firsttime=true; |
redplam | 4:5213bee8158e | 10 | } |
redplam | 4:5213bee8158e | 11 | |
redplam | 4:5213bee8158e | 12 | DHT::~DHT() { |
redplam | 4:5213bee8158e | 13 | } |
redplam | 4:5213bee8158e | 14 | |
redplam | 4:5213bee8158e | 15 | int DHT::readData() { |
redplam | 4:5213bee8158e | 16 | int i, j, retryCount,b; |
redplam | 4:5213bee8158e | 17 | unsigned int bitTimes[DHT_DATA_BIT_COUNT]; |
redplam | 4:5213bee8158e | 18 | |
redplam | 4:5213bee8158e | 19 | eError err = ERROR_NONE; |
redplam | 4:5213bee8158e | 20 | time_t currentTime = time(NULL); |
redplam | 4:5213bee8158e | 21 | |
redplam | 4:5213bee8158e | 22 | DigitalInOut DHT_io(_pin); |
redplam | 4:5213bee8158e | 23 | |
redplam | 4:5213bee8158e | 24 | for (i = 0; i < DHT_DATA_BIT_COUNT; i++) { |
redplam | 4:5213bee8158e | 25 | bitTimes[i] = 0; |
redplam | 4:5213bee8158e | 26 | } |
redplam | 4:5213bee8158e | 27 | |
redplam | 4:5213bee8158e | 28 | if (!_firsttime) { |
redplam | 4:5213bee8158e | 29 | if (int(currentTime - _lastReadTime) < 2) { |
redplam | 4:5213bee8158e | 30 | err = ERROR_NO_PATIENCE; |
redplam | 4:5213bee8158e | 31 | return err; |
redplam | 4:5213bee8158e | 32 | } |
redplam | 4:5213bee8158e | 33 | } else { |
redplam | 4:5213bee8158e | 34 | _firsttime=false; |
redplam | 4:5213bee8158e | 35 | _lastReadTime=currentTime; |
redplam | 4:5213bee8158e | 36 | } |
redplam | 4:5213bee8158e | 37 | retryCount = 0; |
redplam | 4:5213bee8158e | 38 | |
redplam | 4:5213bee8158e | 39 | do { |
redplam | 4:5213bee8158e | 40 | if (retryCount > 125) { |
redplam | 4:5213bee8158e | 41 | err = BUS_BUSY; |
redplam | 4:5213bee8158e | 42 | return err; |
redplam | 4:5213bee8158e | 43 | } |
redplam | 4:5213bee8158e | 44 | retryCount ++; |
redplam | 4:5213bee8158e | 45 | wait_us(2); |
redplam | 4:5213bee8158e | 46 | } while ((DHT_io==0)); |
redplam | 4:5213bee8158e | 47 | |
redplam | 4:5213bee8158e | 48 | |
redplam | 4:5213bee8158e | 49 | DHT_io.output(); |
redplam | 4:5213bee8158e | 50 | DHT_io = 0; |
redplam | 4:5213bee8158e | 51 | wait_ms(18); |
redplam | 4:5213bee8158e | 52 | DHT_io = 1; |
redplam | 4:5213bee8158e | 53 | wait_us(40); |
redplam | 4:5213bee8158e | 54 | DHT_io.input(); |
redplam | 4:5213bee8158e | 55 | |
redplam | 4:5213bee8158e | 56 | retryCount = 0; |
redplam | 4:5213bee8158e | 57 | do { |
redplam | 4:5213bee8158e | 58 | if (retryCount > 40) { |
redplam | 4:5213bee8158e | 59 | err = ERROR_NOT_PRESENT; |
redplam | 4:5213bee8158e | 60 | return err; |
redplam | 4:5213bee8158e | 61 | } |
redplam | 4:5213bee8158e | 62 | retryCount++; |
redplam | 4:5213bee8158e | 63 | wait_us(1); |
redplam | 4:5213bee8158e | 64 | } while ((DHT_io==1)); |
redplam | 4:5213bee8158e | 65 | |
redplam | 4:5213bee8158e | 66 | if (err != ERROR_NONE) { |
redplam | 4:5213bee8158e | 67 | return err; |
redplam | 4:5213bee8158e | 68 | } |
redplam | 4:5213bee8158e | 69 | |
redplam | 4:5213bee8158e | 70 | wait_us(80); |
redplam | 4:5213bee8158e | 71 | |
redplam | 4:5213bee8158e | 72 | for (i = 0; i < 5; i++) { |
redplam | 4:5213bee8158e | 73 | for (j = 0; j < 8; j++) { |
redplam | 4:5213bee8158e | 74 | |
redplam | 4:5213bee8158e | 75 | retryCount = 0; |
redplam | 4:5213bee8158e | 76 | do { |
redplam | 4:5213bee8158e | 77 | if (retryCount > 75) { |
redplam | 4:5213bee8158e | 78 | err = ERROR_DATA_TIMEOUT; |
redplam | 4:5213bee8158e | 79 | return err; |
redplam | 4:5213bee8158e | 80 | } |
redplam | 4:5213bee8158e | 81 | retryCount++; |
redplam | 4:5213bee8158e | 82 | wait_us(1); |
redplam | 4:5213bee8158e | 83 | } while (DHT_io == 0); |
redplam | 4:5213bee8158e | 84 | wait_us(40); |
redplam | 4:5213bee8158e | 85 | bitTimes[i*8+j]=DHT_io; |
redplam | 4:5213bee8158e | 86 | |
redplam | 4:5213bee8158e | 87 | int count = 0; |
redplam | 4:5213bee8158e | 88 | while (DHT_io == 1 && count < 100) { |
redplam | 4:5213bee8158e | 89 | wait_us(1); |
redplam | 4:5213bee8158e | 90 | count++; |
redplam | 4:5213bee8158e | 91 | } |
redplam | 4:5213bee8158e | 92 | } |
redplam | 4:5213bee8158e | 93 | } |
redplam | 4:5213bee8158e | 94 | DHT_io.output(); |
redplam | 4:5213bee8158e | 95 | DHT_io = 1; |
redplam | 4:5213bee8158e | 96 | for (i = 0; i < 5; i++) { |
redplam | 4:5213bee8158e | 97 | b=0; |
redplam | 4:5213bee8158e | 98 | for (j=0; j<8; j++) { |
redplam | 4:5213bee8158e | 99 | if (bitTimes[i*8+j+1] > 0) { |
redplam | 4:5213bee8158e | 100 | b |= ( 1 << (7-j)); |
redplam | 4:5213bee8158e | 101 | } |
redplam | 4:5213bee8158e | 102 | } |
redplam | 4:5213bee8158e | 103 | DHT_data[i]=b; |
redplam | 4:5213bee8158e | 104 | } |
redplam | 4:5213bee8158e | 105 | |
redplam | 4:5213bee8158e | 106 | //if (DHT_data[4] == ((DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3]) & 0xFF)) { |
redplam | 4:5213bee8158e | 107 | _lastReadTime = currentTime; |
redplam | 4:5213bee8158e | 108 | _lastTemperature=CalcTemperature(); |
redplam | 4:5213bee8158e | 109 | _lastHumidity=CalcHumidity(); |
redplam | 4:5213bee8158e | 110 | |
redplam | 4:5213bee8158e | 111 | //} else { |
redplam | 4:5213bee8158e | 112 | // err = ERROR_CHECKSUM; |
redplam | 4:5213bee8158e | 113 | //} |
redplam | 4:5213bee8158e | 114 | |
redplam | 4:5213bee8158e | 115 | return err; |
redplam | 4:5213bee8158e | 116 | |
redplam | 4:5213bee8158e | 117 | } |
redplam | 4:5213bee8158e | 118 | |
redplam | 4:5213bee8158e | 119 | float DHT::CalcTemperature() { |
redplam | 4:5213bee8158e | 120 | int v; |
redplam | 4:5213bee8158e | 121 | |
redplam | 4:5213bee8158e | 122 | switch (_DHTtype) { |
redplam | 4:5213bee8158e | 123 | case DHT11: |
redplam | 4:5213bee8158e | 124 | v = DHT_data[2]; |
redplam | 4:5213bee8158e | 125 | return float(v); |
redplam | 4:5213bee8158e | 126 | case DHT22: |
redplam | 4:5213bee8158e | 127 | v = DHT_data[2] & 0x7F; |
redplam | 4:5213bee8158e | 128 | v *= 256; |
redplam | 4:5213bee8158e | 129 | v += DHT_data[3]; |
redplam | 4:5213bee8158e | 130 | v /= 10; |
redplam | 4:5213bee8158e | 131 | if (DHT_data[2] & 0x80) |
redplam | 4:5213bee8158e | 132 | v *= -1; |
redplam | 4:5213bee8158e | 133 | return float(v); |
redplam | 4:5213bee8158e | 134 | } |
redplam | 4:5213bee8158e | 135 | return 0; |
redplam | 4:5213bee8158e | 136 | } |
redplam | 4:5213bee8158e | 137 | |
redplam | 4:5213bee8158e | 138 | float DHT::ReadHumidity() { |
redplam | 4:5213bee8158e | 139 | return _lastHumidity; |
redplam | 4:5213bee8158e | 140 | } |
redplam | 4:5213bee8158e | 141 | |
redplam | 4:5213bee8158e | 142 | float DHT::ConvertCelciustoFarenheit(float celsius) { |
redplam | 4:5213bee8158e | 143 | return celsius * 9 / 5 + 32; |
redplam | 4:5213bee8158e | 144 | } |
redplam | 4:5213bee8158e | 145 | |
redplam | 4:5213bee8158e | 146 | float DHT::ConvertCelciustoKelvin(float celsius) { |
redplam | 4:5213bee8158e | 147 | return celsius + 273.15; |
redplam | 4:5213bee8158e | 148 | } |
redplam | 4:5213bee8158e | 149 | |
redplam | 4:5213bee8158e | 150 | // dewPoint function NOAA |
redplam | 4:5213bee8158e | 151 | // reference: http://wahiduddin.net/calc/density_algorithms.htm |
redplam | 4:5213bee8158e | 152 | float DHT::CalcdewPoint(float celsius, float humidity) { |
redplam | 4:5213bee8158e | 153 | float A0= 373.15/(273.15 + celsius); |
redplam | 4:5213bee8158e | 154 | float SUM = -7.90298 * (A0-1); |
redplam | 4:5213bee8158e | 155 | SUM += 5.02808 * log10(A0); |
redplam | 4:5213bee8158e | 156 | SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ; |
redplam | 4:5213bee8158e | 157 | SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ; |
redplam | 4:5213bee8158e | 158 | SUM += log10(1013.246); |
redplam | 4:5213bee8158e | 159 | float VP = pow(10, SUM-3) * humidity; |
redplam | 4:5213bee8158e | 160 | float T = log(VP/0.61078); // temp var |
redplam | 4:5213bee8158e | 161 | return (241.88 * T) / (17.558-T); |
redplam | 4:5213bee8158e | 162 | } |
redplam | 4:5213bee8158e | 163 | |
redplam | 4:5213bee8158e | 164 | // delta max = 0.6544 wrt dewPoint() |
redplam | 4:5213bee8158e | 165 | // 5x faster than dewPoint() |
redplam | 4:5213bee8158e | 166 | // reference: http://en.wikipedia.org/wiki/Dew_point |
redplam | 4:5213bee8158e | 167 | float DHT::CalcdewPointFast(float celsius, float humidity) |
redplam | 4:5213bee8158e | 168 | { |
redplam | 4:5213bee8158e | 169 | float a = 17.271; |
redplam | 4:5213bee8158e | 170 | float b = 237.7; |
redplam | 4:5213bee8158e | 171 | float temp = (a * celsius) / (b + celsius) + log(humidity/100); |
redplam | 4:5213bee8158e | 172 | float Td = (b * temp) / (a - temp); |
redplam | 4:5213bee8158e | 173 | return Td; |
redplam | 4:5213bee8158e | 174 | } |
redplam | 4:5213bee8158e | 175 | |
redplam | 4:5213bee8158e | 176 | float DHT::ReadTemperature(eScale Scale) { |
redplam | 4:5213bee8158e | 177 | if (Scale == FARENHEIT) |
redplam | 4:5213bee8158e | 178 | return ConvertCelciustoFarenheit(_lastTemperature); |
redplam | 4:5213bee8158e | 179 | else if (Scale == KELVIN) |
redplam | 4:5213bee8158e | 180 | return ConvertCelciustoKelvin(_lastTemperature); |
redplam | 4:5213bee8158e | 181 | else |
redplam | 4:5213bee8158e | 182 | return _lastTemperature; |
redplam | 4:5213bee8158e | 183 | } |
redplam | 4:5213bee8158e | 184 | |
redplam | 4:5213bee8158e | 185 | float DHT::CalcHumidity() { |
redplam | 4:5213bee8158e | 186 | int v; |
redplam | 4:5213bee8158e | 187 | |
redplam | 4:5213bee8158e | 188 | switch (_DHTtype) { |
redplam | 4:5213bee8158e | 189 | case DHT11: |
redplam | 4:5213bee8158e | 190 | v = DHT_data[0]; |
redplam | 4:5213bee8158e | 191 | return float(v); |
redplam | 4:5213bee8158e | 192 | case DHT22: |
redplam | 4:5213bee8158e | 193 | v = DHT_data[0]; |
redplam | 4:5213bee8158e | 194 | v *= 256; |
redplam | 4:5213bee8158e | 195 | v += DHT_data[1]; |
redplam | 4:5213bee8158e | 196 | v /= 10; |
redplam | 4:5213bee8158e | 197 | return float(v); |
redplam | 4:5213bee8158e | 198 | } |
redplam | 4:5213bee8158e | 199 | return 0; |
redplam | 4:5213bee8158e | 200 | } |
redplam | 4:5213bee8158e | 201 |