檢查 Ubuntu release 版本

簡單指令：

lsb_release -a

執行結果範例：

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 15.04
Release:        15.04
Codename:       vivid

Raspberry Pi DHT11溫溼度感測器 + MQTT 傳送感測訊息

1. Ubuntu Server 擔任 MQTT Server

sudo apt-add-repository ppa:mosquitto-dev/mosquitto-ppa 
sudo apt-get update 
sudo apt-get install mosquitto
sudo apt-get install mosquitto-clients



2. Ubuntu 向執行MQTT Server註冊接收來自hello/world 的訊息

mosquitto_sub -d -t hello/world

視窗暫時不要關閉

3. Raspberry 安裝 DHT11 溫溼度感測器及軟體
可參考 葉難：Raspberry Pi 溫溼度感測器DHT11

sudo apt-get update
sudo apt-get install build-essential python-dev
git clone https://github.com/adafruit/Adafruit_Python_DHT.git
cd Adafruit_Python_DHT
sudo python setup.py install



4. 讀取Pi上溫溼度感測結果，DHT11感測器data pin接在Pi上GPIO 2

cd examples
sudo ./AdafruitDHT.py 11 2

執行結果：

Temp=25.0*  Humidity=48.0%



5. Raspberry Pi 安裝 MQTT Client

wget http://repo.mosquitto.org/debian/mosquitto-repo.gpg.key
sudo apt-key add mosquitto-repo.gpg.key
cd /etc/apt/sources.list.d/

接著視 Pi 作業系統版本而定

sudo wget http://repo.mosquitto.org/debian/mosquitto-wheezy.list

或

sudo wget http://repo.mosquitto.org/debian/mosquitto-jessie.list

sudo apt-get update
sudo apt-get install mosquitto
sudo apt-get install mosquitto-clients



6. Pi 向 Ubuntu MQTT Server (IP:192.168.0.xx) 註冊接收來自 hello/world 的訊息

mosquitto_sub -h 192.168.0.xx -d -t hello/world



7. Pi執行讀取DHT11感測器資料，並將結果作為訊息內容發佈到 hello/world

mosquitto_pub -h 192.168.0.xx -d -t hello/world -m "`/root/AdafruitDHT.py 11 2`"



8. Ubuntu或Pi上向MQTT Server註冊接收來自hello/world 訊息的視窗
應該都可以看到類似的執行結果：

Client mosqsub/30610-myUbuntu received PINGRESP
Client mosqsub/30610-myUbuntu received PUBLISH (d0, q0, r0, m0, 'hello/world', ... (26 bytes))
Temp=25.0*  Humidity=48.0%

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延伸閱讀：

• Install and Test Mosquitto (MQTT) on Ubuntu and OSX
• 葉難：Raspberry Pi 溫溼度感測器DHT11
• GPIO：Raspberry Pi Models A and B

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