Προγραμματισμός ΙΙ: RPi Thermo-Humidity Meter

Tools and practices: RPi Thermo and humidity meter

• Στέφανος Γεωργίου

Problem

• Want to measure temperature rooms in a cool way?
  
• Want to automate this process too?
  
• Want to get measurements remotely?

Tools and Equipments

• Raspberry Pi (I am using 3B model)
  
• Waveshare DHT11 temperature-humidity sensor (3.4 eu)

Set up a Static IP on RPi

• Open a terminal and inside /etc/dhcpcd.conf write the following lines:

  interface [wlan0||eth0]
  static ip_address=192.168.1.2/24
  static routers=192.168.1.1
  static domain_name_servers=192.168.1.1

• Reboot RPi and check IP ($ ifconfig)

RPi GPIO

Add pins to RPi GPIO

• DHT-11 VCC pin to RPi (Top left 3.3VPWR number 1 pin)
  
• DHT-11 GND pin to RPi (Top right GND number 6 pin)
  
• DHT-11 DOUT pin to RPI (Top left GPIO 17 number 11 pin)

Clone Python utility

• git clone https://github.com/szazo/DHT11_Python.git
  
• Modify example.py instance = dht11.DHT11(pin=14) to instance = dht11.DHT11(pin=17)
  
• Execute tool using: $ python3 example.py

To get reading remotely

• Modify example script to avoid infinite loop by removing the while true
  
• Establish password-less ssh using the following tutorial: https://www.tecmint.com/ssh-passwordless-login-using-ssh-keygen-in-5-easy-steps/
  
• Test using the following: $ ssh "python3 DHT11_Python/example.py"

Add in Unix System Resource binaries

• Create a small BASH script with the following code:

cat << EOF > getRoomTemperature 
#!/bin/bash
ssh pi@192.168.1.2 "python3 DHT11_Python/example.py"
EOF

• chmod +x getRoomTemperature
  
• Copy to usr binaries: $ cp getRoomTemperature /usr/bin/
  
• Execute: $ getRoomTemperature

Thank you for your attention