物联网：Python传送温湿度信息到AWS IoT

与 IoT 相关的云端服务为数众多，例如：ThingSpeak、WoT．City、AWS、IBM Bluemix、MediaTek MCS、Google Firebase 等，并在透过这些云端服务可在对数据进行数据可视化、数据分析与其它的应用，而本文用Python将透过 Raspberry Pi 采集到的温湿度信息传送到 AWS IoT。

情境

材料与准备

1．准备 Raspberry Pi 3Model B 开发板

2．准备 Micro SD （已安装 Raspbian）

3．将 Micro SD 装入到 RaspberryPi 中

4．设定好网络

5．安装 GrovePi＋

6．安装 Grove – Temperatureand Humidity Sensor （D4）

7．安装 GROVE － LCD RGBBACKLIGHT （I2C－2）

8．安装 IDE （ Sublime Textor Visual Studio Code ）

Sensor， LCD， GrovePi＋ 与 RaspberryPi 连接如下图

AWS IoT 端

Step 1． 到 AWS 网站申请账号

Step 2． 登入 AWS 网站

Step 3． 点击 Services  AWS IoT

Step 4． 点击 Create a resource

Step 5． 点击 Create a thing 输入 thing Name  Create

Step 6． 点击刚建立的 thing

Step 7． 点击 Connect a device

Step 8． 点击 Node．js  Generate certificate and policy

Step 9． 下载 private 与 public keys

Step 10． 点击 Confirm ＆connecting

Step 11． 点击 Return to ThingDetail

Raspberry Pi 端

Step 1． 透过 Python 读取温湿度信息并传送到AWS IoT

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＃ import Package

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import time

import datetime

import paho．mqtt．client as paho

import json

import ssl

import sys

sys．path．append（＇／home／pi／rpi／code／Package＇）

import grovepi

from grove＿rgb＿lcd import ＊

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＃ Set Pin No， AWS Config

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sensor ＝ 4

blue ＝ 0   ＃ The Blue colored sensor．

white ＝ 1  ＃ The White colored sensor．

connflag ＝ False

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＃ Set AWS Connection

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def on＿connect（client， userdata， flags，rc）：

global connflag

connflag ＝ True

print（＂Connection returned result： ＂ ＋ str（rc） ）

def on＿message（client， userdata， msg）：

print（msg．topic＋＂ ＂＋str（msg．payload））

mqttc ＝ paho．Client（）

mqttc．on＿connect ＝ on＿connect

mqttc．on＿message ＝ on＿message

awshost ＝ ＂a3iprlpgye4dmu．iot．us－west－2．amazonaws．com＂

awsport ＝ 8883

clientId ＝ ＂sensorData＂

thingName ＝ ＂sensorData＂

caPath ＝ ＂．／root－CA．crt＂

certPath ＝＂．／000cd28455－certificate．pem．crt＂

keyPath ＝ ＂．／000cd28455－private．pem．key＂

mqttc．tls＿set（caPath， certfile＝certPath， keyfile＝keyPath，cert＿reqs＝ssl．CERT＿REQUIRED， tls＿version＝ssl．PROTOCOL＿TLSv1＿2， ciphers＝None）

mqttc．connect（awshost， awsport， keepalive＝60）

mqttc．loop＿start（）

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＃ Publish AWS

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while True：

［temp，humidity］ ＝ grovepi．dht（sensor，blue）

print（＂temp ＝ ％．02f C humidity ＝％．02f％％＂％（temp， humidity））

t＝ time．time（）；

date ＝ datetime．datetime．fromtimestamp（t）．strftime（＇％Y％m％d％H％M％S＇）

if connflag ＝＝ True：

mqttc．publish（＂topic／sensorData＂，json．dumps（｛＂time＂： date， ＂temperature＂： temp，＂humidity＂： humidity｝）， qos＝1）

else：

print（＂waiting for connection．．．＂）

time．sleep（1）

Step 2． 将 Python Code 与 Keys 传送到 RaspberryPi

Step 3． 执行刚传到 Raspberry Pi 中的 Python 代码，python 檔名．py

Step 4． Console 执行画面

作者：Archer Huang