Author | Sebastien Lelong, Copyright © 2011, all rights reserved. |
Adapted-by | |
Compiler | >=2.4o |
DHT11 is a cheap temperature and humidity sensor. This library accesses this module and reads values from it. . Accessing the module is quite straight forward and requires one signal pin and a pullup resistor. This pin will be set as output and input by the library itself, and is used to activate the sensor, then actually getting values. Temp & humidity values comes in one frame from the sensor. Library split both value type and set global variables. This means these global variables store the last accessed value. Variables are word storing floating point value. Eg: when humidity is 652, then it means its 65.2 . This library will also work with the more accurate DHT22 version, just declare a "USE_DHT22" const set to true. DHT22 is also known as RHT03. Careful though, most people report RHT03 needs 5V to properly work, and DHT22 at least 3V3. If you receive timeouts with these when powered with 3V3, give a try with 5V.
- datasheet: http://www.robotshop.com/PDF/dht11.pdf - arduino playground: http://arduino.cc/playground/Main/DHT11Lib
const byte DHT11_TIMEOUT = 2
const byte DHT11_OK = 0
const byte DHT11_ERR = 1
var word dht11_temperature = 0
var byte _dht11_buffer[5] = {0,0,0,0,0}
var word dht11_humidity = 0
const byte DHT11_TIMEOUT = 2
No documentation found
const byte DHT11_OK = 0
user-friendly status
const byte DHT11_ERR = 1
No documentation found
var word dht11_temperature = 0
global variables to store temperature and humidity values
var byte _dht11_buffer[5] = {0,0,0,0,0}
No documentation found
var word dht11_humidity = 0
No documentation found
dht11_read() return byte
Read temperature and humidity value. Expect existing aliases on a signal pin: * pin_dht11 * pin_dht11_direction Returns a byte showing result status,using constants defined by the lib: DHT11_OK: successful reading, global variables are set DHT11_ERR: checksum error while reading DHT11_TIMEOUT: too many time occurs before readings, give up. Calling code must check these returned value in order to know if global variables are actually storing updated values
18f27j53 | 18f27j53_dht11.jal |