Janusz G / DHT11

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

Dependents:   HTTP_SERVER2 lightweight-weather-station

DHT11.h@0:4d4c5ea17d86, 2014-09-10 (annotated)

Committer:
s_inoue_mbed
Date:
Wed Sep 10 15:14:31 2014 +0000
Revision:
0:4d4c5ea17d86
Child:
1:95b80cc3f676
First version of the library for the use of DHT11, temperature and humidity sensor

Who changed what in which revision?

UserRevisionLine numberNew contents of line
s_inoue_mbed 0:4d4c5ea17d86 1 /** @file
s_inoue_mbed 0:4d4c5ea17d86 2 Library for the use of the DHT11, a temperature and humidity sensor
s_inoue_mbed 0:4d4c5ea17d86 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 0:4d4c5ea17d86 20 * if (s != 0) {
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 int readData(void);
s_inoue_mbed 0:4d4c5ea17d86 41
s_inoue_mbed 0:4d4c5ea17d86 42 /** Reading the data from the DHT11
s_inoue_mbed 0:4d4c5ea17d86 43 * @return Error code
s_inoue_mbed 0:4d4c5ea17d86 44 * 0: OK.
s_inoue_mbed 0:4d4c5ea17d86 45 * 1: Reading the data too often.
s_inoue_mbed 0:4d4c5ea17d86 46 * 2: 1-wire bus is busy.
s_inoue_mbed 0:4d4c5ea17d86 47 * 3: DHT11 does not respond.
s_inoue_mbed 0:4d4c5ea17d86 48 * 4: DHT11 is not ready.
s_inoue_mbed 0:4d4c5ea17d86 49 * 5: Checksum is incorrect.
s_inoue_mbed 0:4d4c5ea17d86 50 * 6: Timeout
s_inoue_mbed 0:4d4c5ea17d86 51 */
s_inoue_mbed 0:4d4c5ea17d86 52
s_inoue_mbed 0:4d4c5ea17d86 53 /** Reading the humidity from the data
s_inoue_mbed 0:4d4c5ea17d86 54 * @return Humidity in % if readData() returns no error. Otherwise, returns 0xffffffff.
s_inoue_mbed 0:4d4c5ea17d86 55 */
s_inoue_mbed 0:4d4c5ea17d86 56 int readHumidity(void);
s_inoue_mbed 0:4d4c5ea17d86 57
s_inoue_mbed 0:4d4c5ea17d86 58 /** Reading the humidity from the data
s_inoue_mbed 0:4d4c5ea17d86 59 * @return Temperature in Celcius if readData() returns no error. Otherwise, returns 0xffffffff.
s_inoue_mbed 0:4d4c5ea17d86 60 */
s_inoue_mbed 0:4d4c5ea17d86 61 int readTemperature(void);
s_inoue_mbed 0:4d4c5ea17d86 62
s_inoue_mbed 0:4d4c5ea17d86 63 enum ErrorDHT11 {
s_inoue_mbed 0:4d4c5ea17d86 64 OK = 0,
s_inoue_mbed 0:4d4c5ea17d86 65 TOO_FAST_READ = 1,
s_inoue_mbed 0:4d4c5ea17d86 66 BUS_BUSY = 2,
s_inoue_mbed 0:4d4c5ea17d86 67 NOT_PRESENT = 3,
s_inoue_mbed 0:4d4c5ea17d86 68 NOT_READY = 4,
s_inoue_mbed 0:4d4c5ea17d86 69 CHKSUM_ERR = 5,
s_inoue_mbed 0:4d4c5ea17d86 70 WATCHDOG_ERR = 6,
s_inoue_mbed 0:4d4c5ea17d86 71 };
s_inoue_mbed 0:4d4c5ea17d86 72
s_inoue_mbed 0:4d4c5ea17d86 73 private:
s_inoue_mbed 0:4d4c5ea17d86 74 PinName _pin;
s_inoue_mbed 0:4d4c5ea17d86 75 DigitalInOut io;
s_inoue_mbed 0:4d4c5ea17d86 76 InterruptIn io_irq;
s_inoue_mbed 0:4d4c5ea17d86 77 Timer t;
s_inoue_mbed 0:4d4c5ea17d86 78 uint32_t t_pulse_us;
s_inoue_mbed 0:4d4c5ea17d86 79 bool first_time;
s_inoue_mbed 0:4d4c5ea17d86 80 uint64_t data;
s_inoue_mbed 0:4d4c5ea17d86 81 uint32_t chksum;
s_inoue_mbed 0:4d4c5ea17d86 82 uint32_t cnt;
s_inoue_mbed 0:4d4c5ea17d86 83 uint32_t wdt;
s_inoue_mbed 0:4d4c5ea17d86 84 bool eod;
s_inoue_mbed 0:4d4c5ea17d86 85 ErrorDHT11 err;
s_inoue_mbed 0:4d4c5ea17d86 86 void init(void);
s_inoue_mbed 0:4d4c5ea17d86 87 void pos_edge(void);
s_inoue_mbed 0:4d4c5ea17d86 88 void neg_edge(void);
s_inoue_mbed 0:4d4c5ea17d86 89 };
s_inoue_mbed 0:4d4c5ea17d86 90
s_inoue_mbed 0:4d4c5ea17d86 91 #endif