Janusz G / DHT11

A library for the use of DHT11, a temperature and humidity sensor

Dependents:   HTTP_SERVER2 lightweight-weather-station

DHT11.h@4:48798b126d93, 2014-09-10 (annotated)

Committer:
s_inoue_mbed
Date:
Wed Sep 10 17:18:28 2014 +0000
Revision:
4:48798b126d93
Parent:
3:8cd064147bde
Child:
5:da586c935e88
Doxygen documentation has been corrected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
s_inoue_mbed 4:48798b126d93 1 /*
s_inoue_mbed 4:48798b126d93 2 * Library for the use of the DHT11, a temperature and humidity sensor
s_inoue_mbed 4:48798b126d93 3 * Shigenori Inoue, September 10, 2014
s_inoue_mbed 0:4d4c5ea17d86 4 */
s_inoue_mbed 0:4d4c5ea17d86 5 #ifndef __DHT11__
s_inoue_mbed 0:4d4c5ea17d86 6 #define __DHT11__
s_inoue_mbed 0:4d4c5ea17d86 7 #include "mbed.h"
s_inoue_mbed 0:4d4c5ea17d86 8
s_inoue_mbed 0:4d4c5ea17d86 9 /** Example:
s_inoue_mbed 0:4d4c5ea17d86 10 * @code
s_inoue_mbed 0:4d4c5ea17d86 11 * #include "mbed.h"
s_inoue_mbed 0:4d4c5ea17d86 12 * #include "DHT11.h"
s_inoue_mbed 0:4d4c5ea17d86 13 *
s_inoue_mbed 0:4d4c5ea17d86 14 * DHT11 d;
s_inoue_mbed 0:4d4c5ea17d86 15 *
s_inoue_mbed 0:4d4c5ea17d86 16 * main()
s_inoue_mbed 0:4d4c5ea17d86 17 * {
s_inoue_mbed 0:4d4c5ea17d86 18 * int s;
s_inoue_mbed 0:4d4c5ea17d86 19 * s = d.readData();
s_inoue_mbed 2:1e997b7a1f9a 20 * if (s != DHT11::OK) {
s_inoue_mbed 0:4d4c5ea17d86 21 * printf("Error!\r\n");
s_inoue_mbed 0:4d4c5ea17d86 22 * }
s_inoue_mbed 0:4d4c5ea17d86 23 * else {
s_inoue_mbed 0:4d4c5ea17d86 24 * printf("T:%d, H:%d\r\n", d.readTemperature(), d.readHumidity());
s_inoue_mbed 0:4d4c5ea17d86 25 * }
s_inoue_mbed 0:4d4c5ea17d86 26 * }
s_inoue_mbed 0:4d4c5ea17d86 27 * @endcode
s_inoue_mbed 0:4d4c5ea17d86 28 */
s_inoue_mbed 0:4d4c5ea17d86 29
s_inoue_mbed 0:4d4c5ea17d86 30 class DHT11
s_inoue_mbed 0:4d4c5ea17d86 31 {
s_inoue_mbed 0:4d4c5ea17d86 32 public:
s_inoue_mbed 0:4d4c5ea17d86 33 /** Create a DHT11 interface
s_inoue_mbed 0:4d4c5ea17d86 34 * @param pin 1-wire-like serial I/O port of DHT11
s_inoue_mbed 0:4d4c5ea17d86 35 */
s_inoue_mbed 0:4d4c5ea17d86 36 DHT11(PinName pin);
s_inoue_mbed 0:4d4c5ea17d86 37 ~DHT11();
s_inoue_mbed 0:4d4c5ea17d86 38
s_inoue_mbed 0:4d4c5ea17d86 39 /** Reading the data from the DHT11
s_inoue_mbed 0:4d4c5ea17d86 40 * @return Error code
s_inoue_mbed 0:4d4c5ea17d86 41 * 0: OK.
s_inoue_mbed 0:4d4c5ea17d86 42 * 1: Reading the data too often.
s_inoue_mbed 0:4d4c5ea17d86 43 * 2: 1-wire bus is busy.
s_inoue_mbed 0:4d4c5ea17d86 44 * 3: DHT11 does not respond.
s_inoue_mbed 0:4d4c5ea17d86 45 * 4: DHT11 is not ready.
s_inoue_mbed 0:4d4c5ea17d86 46 * 5: Checksum is incorrect.
s_inoue_mbed 0:4d4c5ea17d86 47 * 6: Timeout
s_inoue_mbed 0:4d4c5ea17d86 48 */
s_inoue_mbed 3:8cd064147bde 49 int readData(void);
s_inoue_mbed 3:8cd064147bde 50
s_inoue_mbed 0:4d4c5ea17d86 51 /** Reading the humidity from the data
s_inoue_mbed 0:4d4c5ea17d86 52 * @return Humidity in % if readData() returns no error. Otherwise, returns 0xffffffff.
s_inoue_mbed 0:4d4c5ea17d86 53 */
s_inoue_mbed 0:4d4c5ea17d86 54 int readHumidity(void);
s_inoue_mbed 3:8cd064147bde 55
s_inoue_mbed 3:8cd064147bde 56 /** Reading the temperature from the data
s_inoue_mbed 0:4d4c5ea17d86 57 * @return Temperature in Celcius if readData() returns no error. Otherwise, returns 0xffffffff.
s_inoue_mbed 0:4d4c5ea17d86 58 */
s_inoue_mbed 0:4d4c5ea17d86 59 int readTemperature(void);
s_inoue_mbed 3:8cd064147bde 60
s_inoue_mbed 0:4d4c5ea17d86 61 enum ErrorDHT11 {
s_inoue_mbed 0:4d4c5ea17d86 62 OK = 0,
s_inoue_mbed 0:4d4c5ea17d86 63 TOO_FAST_READ = 1,
s_inoue_mbed 0:4d4c5ea17d86 64 BUS_BUSY = 2,
s_inoue_mbed 0:4d4c5ea17d86 65 NOT_PRESENT = 3,
s_inoue_mbed 0:4d4c5ea17d86 66 NOT_READY = 4,
s_inoue_mbed 0:4d4c5ea17d86 67 CHKSUM_ERR = 5,
s_inoue_mbed 0:4d4c5ea17d86 68 WATCHDOG_ERR = 6,
s_inoue_mbed 0:4d4c5ea17d86 69 };
s_inoue_mbed 0:4d4c5ea17d86 70
s_inoue_mbed 0:4d4c5ea17d86 71 private:
s_inoue_mbed 0:4d4c5ea17d86 72 PinName _pin;
s_inoue_mbed 0:4d4c5ea17d86 73 DigitalInOut io;
s_inoue_mbed 0:4d4c5ea17d86 74 InterruptIn io_irq;
s_inoue_mbed 0:4d4c5ea17d86 75 Timer t;
s_inoue_mbed 0:4d4c5ea17d86 76 uint32_t t_pulse_us;
s_inoue_mbed 0:4d4c5ea17d86 77 bool first_time;
s_inoue_mbed 0:4d4c5ea17d86 78 uint64_t data;
s_inoue_mbed 0:4d4c5ea17d86 79 uint32_t chksum;
s_inoue_mbed 0:4d4c5ea17d86 80 uint32_t cnt;
s_inoue_mbed 0:4d4c5ea17d86 81 uint32_t wdt;
s_inoue_mbed 0:4d4c5ea17d86 82 bool eod;
s_inoue_mbed 0:4d4c5ea17d86 83 ErrorDHT11 err;
s_inoue_mbed 0:4d4c5ea17d86 84 void init(void);
s_inoue_mbed 0:4d4c5ea17d86 85 void pos_edge(void);
s_inoue_mbed 0:4d4c5ea17d86 86 void neg_edge(void);
s_inoue_mbed 0:4d4c5ea17d86 87 };
s_inoue_mbed 0:4d4c5ea17d86 88
s_inoue_mbed 0:4d4c5ea17d86 89 #endif