DHT12 數位式溫濕度感測器

感測器簡介

DHT12 數位式溫濕度感測器是一款含有己校準數位信號輸出的溫濕度複合型感測器，為 DHT11 的升級產品。它應用專用的數位模組採集技術和半導體溫濕度感測器，確保產品具有較高的可靠性與卓越的長期穩定性。

DHT12 感測器I²C 通信協議

DHT12 支援 I²C 方式進行通訊，完全按照 I²C 標準協議編制，可直接掛在 I²C 匯流排上；感測器SDA 引腳作接I²C 資料匯流排,SCL 接I²C 時鐘匯流排，客戶使用時需給這兩個引腳接一個 1kΩ~10kΩ的上拉電阻。I²C地址為 0xB8(DEV SEL); I²C 通訊速率不能高於 400kHz。

I²C 介面特性

必須嚴格遵照以下通訊規格，否則感測器無法正常工作。

通訊協定：

讀取時序：

參考時序：

電路圖

程式列表

Python - DHT12.py

"""

MicroPython Aosong DHT12 I2C driver

https://github.com/mcauser/micropython-dht12

MIT License

Copyright (c) 2016 Mike Causer

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation 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

furnished 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 FOR 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.

"""

class DHTBaseI2C:

def __init__(self, i2c, addr=0x5c):

self.i2c = i2c

self.addr = addr

self.buf = bytearray(5)

def measure(self):

buf = self.buf

temp = 0x00

self.i2c.send(temp,self.addr) # i2c_error: i2c write fail!input buffer length is not correct !

self.i2c.recv(buf,self.addr) # Ū¨ú5­Ó¦r¸`

if ((buf[0] + buf[1] + buf[2] + buf[3]) & 0xff) != buf[4]:

print("checksum error")

print("%x,%x,%x,%x,%x"%(buf[0],buf[1],buf[2],buf[3],buf[4]))

#raise Exception("checksum error")

class DHT12(DHTBaseI2C):

def humidity(self):

return self.buf[0] + self.buf[1] * 0.1

def temperature(self):

t = self.buf[2] + (self.buf[3] & 0x7f) * 0.1

if self.buf[3] & 0x80:

t = -t

return t

Python - ePy-Lite_DHT12.py

from machine import I2C, Pin

from machine import Switch #Get button KEY library

import utime

import dht12

i2c_0 = None

# Start Function

if __name__=="__main__":

KeyA = Switch('keya') #Create button A

# Declaration I2C

i2c_0 = I2C(0,I2C.MASTER,baudrate=10000) #Create I2C0 Master Mode, Baudrate=10kHz

sensor = dht12.DHT12(i2c_0)

print("Start humidity measurement.")

while True:

sensor.measure()

print("Temperature:%.1f"%(sensor.temperature()))

print("Humidity:%.1f"%(sensor.humidity()))

if (KeyA.value()) == True: #Press A Key

break

utime.sleep(1)

i2c_0.deinit()

# KeyA.deinit()

print("Exit humidity measurement.")

執行結果