DHT_TestProgram - DHT testprogram

Users » Wimpie » Code » DHT_TestProgram

Wim De Roeve / Mbed 2 deprecated DHT_TestProgram

DHT testprogram

DHT/DHT.cpp@0:9ef709bfeb08, 2012-07-10 (annotated)

Committer:: Wimpie
Date:: Tue Jul 10 13:11:23 2012 +0000
Revision:: 0:9ef709bfeb08

Who changed what in which revision?

User	Revision	Line number	New contents of line
Wimpie	0:9ef709bfeb08	1	/*
Wimpie	0:9ef709bfeb08	2	* DHT Library for Digital-output Humidity and Temperature sensors
Wimpie	0:9ef709bfeb08	3	*
Wimpie	0:9ef709bfeb08	4	* Works with DHT11, DHT22
Wimpie	0:9ef709bfeb08	5	* SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio)
Wimpie	0:9ef709bfeb08	6	* SEN51035P, Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
Wimpie	0:9ef709bfeb08	7	* AM2302 , temperature-humidity sensor
Wimpie	0:9ef709bfeb08	8	* HM2303 , Digital-output humidity and temperature sensor
Wimpie	0:9ef709bfeb08	9	*
Wimpie	0:9ef709bfeb08	10	* Copyright (C) Wim De Roeve
Wimpie	0:9ef709bfeb08	11	* based on DHT22 sensor library by HO WING KIT
Wimpie	0:9ef709bfeb08	12	* Arduino DHT11 library
Wimpie	0:9ef709bfeb08	13	*
Wimpie	0:9ef709bfeb08	14	* Permission is hereby granted, free of charge, to any person obtaining a copy
Wimpie	0:9ef709bfeb08	15	* of this software and associated documnetation files (the "Software"), to deal
Wimpie	0:9ef709bfeb08	16	* in the Software without restriction, including without limitation the rights
Wimpie	0:9ef709bfeb08	17	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
Wimpie	0:9ef709bfeb08	18	* copies of the Software, and to permit persons to whom the Software is
Wimpie	0:9ef709bfeb08	19	* furished to do so, subject to the following conditions:
Wimpie	0:9ef709bfeb08	20	*
Wimpie	0:9ef709bfeb08	21	* The above copyright notice and this permission notice shall be included in
Wimpie	0:9ef709bfeb08	22	* all copies or substantial portions of the Software.
Wimpie	0:9ef709bfeb08	23	*
Wimpie	0:9ef709bfeb08	24	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Wimpie	0:9ef709bfeb08	25	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Wimpie	0:9ef709bfeb08	26	* FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
Wimpie	0:9ef709bfeb08	27	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Wimpie	0:9ef709bfeb08	28	* LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
Wimpie	0:9ef709bfeb08	29	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
Wimpie	0:9ef709bfeb08	30	* THE SOFTWARE.
Wimpie	0:9ef709bfeb08	31	*/
Wimpie	0:9ef709bfeb08	32
Wimpie	0:9ef709bfeb08	33	#include "DHT.h"
Wimpie	0:9ef709bfeb08	34
Wimpie	0:9ef709bfeb08	35	#define DHT_DATA_BIT_COUNT 41
Wimpie	0:9ef709bfeb08	36
Wimpie	0:9ef709bfeb08	37	DHT::DHT(PinName pin,int DHTtype) {
Wimpie	0:9ef709bfeb08	38	_pin = pin;
Wimpie	0:9ef709bfeb08	39	_DHTtype = DHTtype;
Wimpie	0:9ef709bfeb08	40	_firsttime=true;
Wimpie	0:9ef709bfeb08	41	}
Wimpie	0:9ef709bfeb08	42
Wimpie	0:9ef709bfeb08	43	DHT::~DHT() {
Wimpie	0:9ef709bfeb08	44	}
Wimpie	0:9ef709bfeb08	45
Wimpie	0:9ef709bfeb08	46	int DHT::readData() {
Wimpie	0:9ef709bfeb08	47	int i, j, retryCount,b;
Wimpie	0:9ef709bfeb08	48	unsigned int bitTimes[DHT_DATA_BIT_COUNT];
Wimpie	0:9ef709bfeb08	49
Wimpie	0:9ef709bfeb08	50	eError err = ERROR_NONE;
Wimpie	0:9ef709bfeb08	51	time_t currentTime = time(NULL);
Wimpie	0:9ef709bfeb08	52
Wimpie	0:9ef709bfeb08	53	DigitalInOut DHT_io(_pin);
Wimpie	0:9ef709bfeb08	54
Wimpie	0:9ef709bfeb08	55	for (i = 0; i < DHT_DATA_BIT_COUNT; i++) {
Wimpie	0:9ef709bfeb08	56	bitTimes[i] = 0;
Wimpie	0:9ef709bfeb08	57	}
Wimpie	0:9ef709bfeb08	58
Wimpie	0:9ef709bfeb08	59	if (!_firsttime) {
Wimpie	0:9ef709bfeb08	60	if (int(currentTime - _lastReadTime) < 2) {
Wimpie	0:9ef709bfeb08	61	err = ERROR_NO_PATIENCE;
Wimpie	0:9ef709bfeb08	62	return err;
Wimpie	0:9ef709bfeb08	63	}
Wimpie	0:9ef709bfeb08	64	} else {
Wimpie	0:9ef709bfeb08	65	_firsttime=false;
Wimpie	0:9ef709bfeb08	66	_lastReadTime=currentTime;
Wimpie	0:9ef709bfeb08	67	}
Wimpie	0:9ef709bfeb08	68	retryCount = 0;
Wimpie	0:9ef709bfeb08	69
Wimpie	0:9ef709bfeb08	70	do {
Wimpie	0:9ef709bfeb08	71	if (retryCount > 125) {
Wimpie	0:9ef709bfeb08	72	err = BUS_BUSY;
Wimpie	0:9ef709bfeb08	73	return err;
Wimpie	0:9ef709bfeb08	74	}
Wimpie	0:9ef709bfeb08	75	retryCount ++;
Wimpie	0:9ef709bfeb08	76	wait_us(2);
Wimpie	0:9ef709bfeb08	77	} while ((DHT_io==0));
Wimpie	0:9ef709bfeb08	78
Wimpie	0:9ef709bfeb08	79
Wimpie	0:9ef709bfeb08	80	DHT_io.output();
Wimpie	0:9ef709bfeb08	81	DHT_io = 0;
Wimpie	0:9ef709bfeb08	82	wait_ms(18);
Wimpie	0:9ef709bfeb08	83	DHT_io = 1;
Wimpie	0:9ef709bfeb08	84	wait_us(40);
Wimpie	0:9ef709bfeb08	85	DHT_io.input();
Wimpie	0:9ef709bfeb08	86
Wimpie	0:9ef709bfeb08	87	retryCount = 0;
Wimpie	0:9ef709bfeb08	88	do {
Wimpie	0:9ef709bfeb08	89	if (retryCount > 40) {
Wimpie	0:9ef709bfeb08	90	err = ERROR_NOT_PRESENT;
Wimpie	0:9ef709bfeb08	91	return err;
Wimpie	0:9ef709bfeb08	92	}
Wimpie	0:9ef709bfeb08	93	retryCount++;
Wimpie	0:9ef709bfeb08	94	wait_us(1);
Wimpie	0:9ef709bfeb08	95	} while ((DHT_io==1));
Wimpie	0:9ef709bfeb08	96
Wimpie	0:9ef709bfeb08	97	if (err != ERROR_NONE) {
Wimpie	0:9ef709bfeb08	98	return err;
Wimpie	0:9ef709bfeb08	99	}
Wimpie	0:9ef709bfeb08	100
Wimpie	0:9ef709bfeb08	101	wait_us(80);
Wimpie	0:9ef709bfeb08	102
Wimpie	0:9ef709bfeb08	103	for (i = 0; i < 5; i++) {
Wimpie	0:9ef709bfeb08	104	for (j = 0; j < 8; j++) {
Wimpie	0:9ef709bfeb08	105
Wimpie	0:9ef709bfeb08	106	retryCount = 0;
Wimpie	0:9ef709bfeb08	107	do {
Wimpie	0:9ef709bfeb08	108	if (retryCount > 75) {
Wimpie	0:9ef709bfeb08	109	err = ERROR_DATA_TIMEOUT;
Wimpie	0:9ef709bfeb08	110	return err;
Wimpie	0:9ef709bfeb08	111	}
Wimpie	0:9ef709bfeb08	112	retryCount++;
Wimpie	0:9ef709bfeb08	113	wait_us(1);
Wimpie	0:9ef709bfeb08	114	} while (DHT_io == 0);
Wimpie	0:9ef709bfeb08	115	wait_us(40);
Wimpie	0:9ef709bfeb08	116	bitTimes[i*8+j]=DHT_io;
Wimpie	0:9ef709bfeb08	117
Wimpie	0:9ef709bfeb08	118	int count = 0;
Wimpie	0:9ef709bfeb08	119	while (DHT_io == 1 && count < 100) {
Wimpie	0:9ef709bfeb08	120	wait_us(1);
Wimpie	0:9ef709bfeb08	121	count++;
Wimpie	0:9ef709bfeb08	122	}
Wimpie	0:9ef709bfeb08	123	}
Wimpie	0:9ef709bfeb08	124	}
Wimpie	0:9ef709bfeb08	125	DHT_io.output();
Wimpie	0:9ef709bfeb08	126	DHT_io = 1;
Wimpie	0:9ef709bfeb08	127	for (i = 0; i < 5; i++) {
Wimpie	0:9ef709bfeb08	128	b=0;
Wimpie	0:9ef709bfeb08	129	for (j=0; j<8; j++) {
Wimpie	0:9ef709bfeb08	130	if (bitTimes[i*8+j+1] > 0) {
Wimpie	0:9ef709bfeb08	131	b \|= ( 1 << (7-j));
Wimpie	0:9ef709bfeb08	132	}
Wimpie	0:9ef709bfeb08	133	}
Wimpie	0:9ef709bfeb08	134	DHT_data[i]=b;
Wimpie	0:9ef709bfeb08	135	}
Wimpie	0:9ef709bfeb08	136
Wimpie	0:9ef709bfeb08	137	if (DHT_data[4] == ((DHT_data[0] + DHT_data[1] + DHT_data[2] + DHT_data[3]) & 0xFF)) {
Wimpie	0:9ef709bfeb08	138	_lastReadTime = currentTime;
Wimpie	0:9ef709bfeb08	139	_lastTemperature=CalcTemperature();
Wimpie	0:9ef709bfeb08	140	_lastHumidity=CalcHumidity();
Wimpie	0:9ef709bfeb08	141
Wimpie	0:9ef709bfeb08	142	} else {
Wimpie	0:9ef709bfeb08	143	err = ERROR_CHECKSUM;
Wimpie	0:9ef709bfeb08	144	}
Wimpie	0:9ef709bfeb08	145
Wimpie	0:9ef709bfeb08	146	return err;
Wimpie	0:9ef709bfeb08	147
Wimpie	0:9ef709bfeb08	148	}
Wimpie	0:9ef709bfeb08	149
Wimpie	0:9ef709bfeb08	150	float DHT::CalcTemperature() {
Wimpie	0:9ef709bfeb08	151	int v;
Wimpie	0:9ef709bfeb08	152
Wimpie	0:9ef709bfeb08	153	switch (_DHTtype) {
Wimpie	0:9ef709bfeb08	154	case DHT11:
Wimpie	0:9ef709bfeb08	155	v = DHT_data[2];
Wimpie	0:9ef709bfeb08	156	return float(v);
Wimpie	0:9ef709bfeb08	157	case DHT22:
Wimpie	0:9ef709bfeb08	158	v = DHT_data[2] & 0x7F;
Wimpie	0:9ef709bfeb08	159	v *= 256;
Wimpie	0:9ef709bfeb08	160	v += DHT_data[3];
Wimpie	0:9ef709bfeb08	161	v /= 10;
Wimpie	0:9ef709bfeb08	162	if (DHT_data[2] & 0x80)
Wimpie	0:9ef709bfeb08	163	v *= -1;
Wimpie	0:9ef709bfeb08	164	return float(v);
Wimpie	0:9ef709bfeb08	165	}
Wimpie	0:9ef709bfeb08	166	return 0;
Wimpie	0:9ef709bfeb08	167	}
Wimpie	0:9ef709bfeb08	168
Wimpie	0:9ef709bfeb08	169	float DHT::ReadHumidity() {
Wimpie	0:9ef709bfeb08	170	return _lastHumidity;
Wimpie	0:9ef709bfeb08	171	}
Wimpie	0:9ef709bfeb08	172
Wimpie	0:9ef709bfeb08	173	float DHT::ConvertCelciustoFarenheit(float celsius) {
Wimpie	0:9ef709bfeb08	174	return celsius * 9 / 5 + 32;
Wimpie	0:9ef709bfeb08	175	}
Wimpie	0:9ef709bfeb08	176
Wimpie	0:9ef709bfeb08	177	float DHT::ConvertCelciustoKelvin(float celsius) {
Wimpie	0:9ef709bfeb08	178	return celsius + 273.15;
Wimpie	0:9ef709bfeb08	179	}
Wimpie	0:9ef709bfeb08	180
Wimpie	0:9ef709bfeb08	181	// dewPoint function NOAA
Wimpie	0:9ef709bfeb08	182	// reference: http://wahiduddin.net/calc/density_algorithms.htm
Wimpie	0:9ef709bfeb08	183	float DHT::CalcdewPoint(float celsius, float humidity) {
Wimpie	0:9ef709bfeb08	184	float A0= 373.15/(273.15 + celsius);
Wimpie	0:9ef709bfeb08	185	float SUM = -7.90298 * (A0-1);
Wimpie	0:9ef709bfeb08	186	SUM += 5.02808 * log10(A0);
Wimpie	0:9ef709bfeb08	187	SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
Wimpie	0:9ef709bfeb08	188	SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
Wimpie	0:9ef709bfeb08	189	SUM += log10(1013.246);
Wimpie	0:9ef709bfeb08	190	float VP = pow(10, SUM-3) * humidity;
Wimpie	0:9ef709bfeb08	191	float T = log(VP/0.61078); // temp var
Wimpie	0:9ef709bfeb08	192	return (241.88 * T) / (17.558-T);
Wimpie	0:9ef709bfeb08	193	}
Wimpie	0:9ef709bfeb08	194
Wimpie	0:9ef709bfeb08	195	// delta max = 0.6544 wrt dewPoint()
Wimpie	0:9ef709bfeb08	196	// 5x faster than dewPoint()
Wimpie	0:9ef709bfeb08	197	// reference: http://en.wikipedia.org/wiki/Dew_point
Wimpie	0:9ef709bfeb08	198	float DHT::CalcdewPointFast(float celsius, float humidity)
Wimpie	0:9ef709bfeb08	199	{
Wimpie	0:9ef709bfeb08	200	float a = 17.271;
Wimpie	0:9ef709bfeb08	201	float b = 237.7;
Wimpie	0:9ef709bfeb08	202	float temp = (a * celsius) / (b + celsius) + log(humidity/100);
Wimpie	0:9ef709bfeb08	203	float Td = (b * temp) / (a - temp);
Wimpie	0:9ef709bfeb08	204	return Td;
Wimpie	0:9ef709bfeb08	205	}
Wimpie	0:9ef709bfeb08	206
Wimpie	0:9ef709bfeb08	207	float DHT::ReadTemperature(eScale Scale) {
Wimpie	0:9ef709bfeb08	208	if (Scale == FARENHEIT)
Wimpie	0:9ef709bfeb08	209	return ConvertCelciustoFarenheit(_lastTemperature);
Wimpie	0:9ef709bfeb08	210	else if (Scale == KELVIN)
Wimpie	0:9ef709bfeb08	211	return ConvertCelciustoKelvin(_lastTemperature);
Wimpie	0:9ef709bfeb08	212	else
Wimpie	0:9ef709bfeb08	213	return _lastTemperature;
Wimpie	0:9ef709bfeb08	214	}
Wimpie	0:9ef709bfeb08	215
Wimpie	0:9ef709bfeb08	216	float DHT::CalcHumidity() {
Wimpie	0:9ef709bfeb08	217	int v;
Wimpie	0:9ef709bfeb08	218
Wimpie	0:9ef709bfeb08	219	switch (_DHTtype) {
Wimpie	0:9ef709bfeb08	220	case DHT11:
Wimpie	0:9ef709bfeb08	221	v = DHT_data[0];
Wimpie	0:9ef709bfeb08	222	return float(v);
Wimpie	0:9ef709bfeb08	223	case DHT22:
Wimpie	0:9ef709bfeb08	224	v = DHT_data[0];
Wimpie	0:9ef709bfeb08	225	v *= 256;
Wimpie	0:9ef709bfeb08	226	v += DHT_data[1];
Wimpie	0:9ef709bfeb08	227	v /= 10;
Wimpie	0:9ef709bfeb08	228	return float(v);
Wimpie	0:9ef709bfeb08	229	}
Wimpie	0:9ef709bfeb08	230	return 0;
Wimpie	0:9ef709bfeb08	231	}
Wimpie	0:9ef709bfeb08	232
Wimpie	0:9ef709bfeb08	233

Repository toolbox

Export to desktop IDE

Build repository

Repository details

Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	10 Jul 2012
Imports:	656
Forks:	1
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	10

DHT/DHT.cpp@0:9ef709bfeb08, 2012-07-10 (annotated)

Who changed what in which revision?

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning