Hyoeun Choi
a
Diff: DHT.cpp
- Revision:
- 5:a0d0e1a0a94a
- Parent:
- 4:1e78a462b211
--- a/DHT.cpp Thu Jul 20 09:04:07 2017 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,227 +0,0 @@
-/*
- * DHT Library for Digital-output Humidity and Temperature sensors
- *
- * Works with DHT11, DHT22
- * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
- * SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
- * AM2302 , temperature-humidity sensor
- * HM2303 , Digital-output humidity and temperature sensor
- *
- * Copyright (C) Wim De Roeve
- * based on DHT22 sensor library by HO WING KIT
- * Arduino DHT11 library
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documnetation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include "DHT.h"
-
-#define DHT_DATA_BIT_COUNT 40
-
-DHT::DHT(PinName pin, eType DHTtype)
-{
- _pin = pin;
- _DHTtype = DHTtype;
- _firsttime = true;
-}
-
-DHT::~DHT()
-{
-
-}
-
-eError DHT::stall(DigitalInOut &io, int const level, int const max_time)
-{
- int cnt = 0;
- while (level == io) {
- if (cnt > max_time) {
- return ERROR_NO_PATIENCE;
- }
- cnt++;
- wait_us(1);
- }
- return ERROR_NONE;
-}
-
-eError DHT::readData()
-{
- uint8_t i = 0, j = 0, b = 0, data_valid = 0;
- uint32_t bit_value[DHT_DATA_BIT_COUNT] = {0};
-
- eError err = ERROR_NONE;
- time_t currentTime = time(NULL);
-
- DigitalInOut DHT_io(_pin);
-
- // IO must be in hi state to start
- if (ERROR_NONE != stall(DHT_io, 0, 250)) {
- return BUS_BUSY;
- }
-
- // start the transfer
- DHT_io.output();
- DHT_io = 0;
- // only 500uS for DHT22 but 18ms for DHT11
- (_DHTtype == 11) ? wait_ms(18) : wait(0.0005);
- DHT_io = 1;
- wait_us(30);
- DHT_io.input();
- // wait till the sensor grabs the bus
- if (ERROR_NONE != stall(DHT_io, 1, 40)) {
- return ERROR_NOT_PRESENT;
- }
- // sensor should signal low 80us and then hi 80us
- if (ERROR_NONE != stall(DHT_io, 0, 100)) {
- return ERROR_SYNC_TIMEOUT;
- }
- if (ERROR_NONE != stall(DHT_io, 1, 100)) {
- return ERROR_NO_PATIENCE;
- }
- // capture the data
- for (i = 0; i < 5; i++) {
- for (j = 0; j < 8; j++) {
- if (ERROR_NONE != stall(DHT_io, 0, 75)) {
- return ERROR_DATA_TIMEOUT;
- }
- // logic 0 is 28us max, 1 is 70us
- wait_us(40);
- bit_value[i*8+j] = DHT_io;
- if (ERROR_NONE != stall(DHT_io, 1, 50)) {
- return ERROR_DATA_TIMEOUT;
- }
- }
- }
- // store the data
- for (i = 0; i < 5; i++) {
- b=0;
- for (j=0; j<8; j++) {
- if (bit_value[i*8+j] == 1) {
- b |= (1 << (7-j));
- }
- }
- DHT_data[i]=b;
- }
-
- // uncomment to see the checksum error if it exists
- //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]);
- data_valid = DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3];
- if (DHT_data[4] == data_valid) {
- _lastReadTime = currentTime;
- _lastTemperature = CalcTemperature();
- _lastHumidity = CalcHumidity();
-
- } else {
- err = ERROR_CHECKSUM;
- }
-
- return err;
-
-}
-
-float DHT::CalcTemperature()
-{
- int v;
-
- switch (_DHTtype) {
- case DHT11:
- v = DHT_data[2];
- return float(v);
- case DHT22:
- v = DHT_data[2] & 0x7F;
- v *= 256;
- v += DHT_data[3];
- v /= 10;
- if (DHT_data[2] & 0x80)
- v *= -1;
- return float(v);
- }
- return 0;
-}
-
-float DHT::ReadHumidity()
-{
- return _lastHumidity+30;
-}
-
-float DHT::ConvertCelciustoFarenheit(float const celsius)
-{
- return celsius * 9 / 5 + 32;
-}
-
-float DHT::ConvertCelciustoKelvin(float const celsius)
-{
- return celsius + 273.15;
-}
-
-// dewPoint function NOAA
-// reference: http://wahiduddin.net/calc/density_algorithms.htm
-float DHT::CalcdewPoint(float const celsius, float const humidity)
-{
- float A0= 373.15/(273.15 + celsius);
- float SUM = -7.90298 * (A0-1);
- SUM += 5.02808 * log10(A0);
- SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
- SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
- SUM += log10(1013.246);
- float VP = pow(10, SUM-3) * (humidity);
- float T = log(VP/0.61078); // temp var
- return (241.88 * T) / (17.558-T);
-}
-
-// delta max = 0.6544 wrt dewPoint()
-// 5x faster than dewPoint()
-// reference: http://en.wikipedia.org/wiki/Dew_point
-/*float DHT::CalcdewPointFast(float const celsius, float const humidity)
-{
- float a = 17.271;
- float b = 237.7;
- float temp = (a * celsius) / (b + celsius) + log(humidity/100);
- float Td = (b * temp) / (a - temp);
- return Td;
-}*/
-
-float DHT::ReadTemperature(eScale Scale)
-{
- if (Scale == FARENHEIT)
- return ConvertCelciustoFarenheit(_lastTemperature);
- else if (Scale == KELVIN)
- return ConvertCelciustoKelvin(_lastTemperature);
- else
- return _lastTemperature;
-}
-
-float DHT::CalcHumidity()
-{
- int v;
-
- switch (_DHTtype) {
- case DHT11:
- v = DHT_data[0];
- return float(v);
- case DHT22:
- v = DHT_data[0];
- v *= 256;
- v += DHT_data[1];
- v /= 10;
- return float(v);
- }
- return 0;
-}
-
-