1. Embedded Software Development with Python and the Raspberry Pi
Class 5: An Internet of Things Weather Station Example
August 22, 2014 Jacob Beningo, CSDP
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2. Course Overview Introduction to Python Python Fundamentals
An Overview of the Raspberry Pi
Controlling Raspberry Pi Peripherals with Python
An Internet of Things Weather Station Example

3. Session Overview An IoT Weather Station Example
The Personal Weather Station (PWS)
Setup a PWS Account
Temperature & Humidity Sensors
PWS Application
PWS Results
Script Automation

4. The Personal Weather Station (PWS)
Thermometer
Barometer
Anemometer
Hygrometer
Wind vanes
UV index
Soil moistness
And more!

5. The Personal Weather Station (PWS)

6. The Personal Weather Station (PWS)
Weather Underground Resources

7. Setup a PWS Account
Registering at Weather Underground

8. Setup A PWS Account
PWS Location

9. Temperature and Humidity Sensors
AM2302 (DHT22)
Capacitive Humidity Sensor
0 – 99.9%
+/- 2%
Thermistor for Temperature
-40 to 80 C
+/- 0.5 C
Digital Single Wire Read
Sample Rate 0.5 Hz ( relatively slow!)

10. Temperature and Humidity Sensors
AM2302 (DHT22) Wiring
Red (3.3V – PI Pin 1)
Yellow (Data – PI Pin 7)
Black ( Ground – PI Pin 6)

11. Temperature and Humidity Sensors
AM2302 (DHT22) Communication Protocol
Manchester “like” encoding
Bit-Bang GPIO using a low level C driver
Installing the Low Level C Driver
Wget -O bcm tar.gz

12. Temperature and Humidity Sensor
Installing the Adafruit DHT Python Driver
git clone
cd Adafruit_Python_DHT
sudo apt-get upgrade
sudo apt-get install build-essential python-dev
sudo python setup.py install
Test the Sensor
sudo python AdafruitDHT.py 22 4
cd Adafruit_Python_DHT/examples
Sensor Type
GPIO 4

13. Personal Weather Station Application
Application Design
Read DHT Sensor
Delay 5 s
Send Data
Verify Sensor Data
Invalid
Prepare Weather URL String
Convert Temperature

14. Personal Weather Station Application
Script Dependencies
Why urllib?
datetime.utcnow()

15. Personal Weather Station Application
Configuration
datetime.utcnow()

16. Personal Weather Station Application
Reading and verifying the sensor
datetime.utcnow()

17. Personal Weather Station Application
Web Connection
datetime.utcnow()

18. Personal Weather Station Application
Web Connection Error Checking
datetime.utcnow()

19. PWS Results
It is live!

20. PWS Results

21. Script Automation Login Automatically Script start on login
sudo nano /etc/initab
comment out
1:2345:respawn:/sbin/getty tty1
Add
1:2345:respawn:/bin/login -f pi tty1 </dev/tty1 >/dev/tty1 2>&1
Script start on login
nano ~/.bashrc
At the bottom add “sudo python /path/pws.py”

22. Going Further Download Template Materials for Web Tutorials YouTube
Python Doxygen Script Template
Personal Weather Station Python Script
Raspberry Pi Example Python Scripts
Web Tutorials
YouTube
From under
Blog and Articles > Software Techniques > Embedded Software with Python

23. Contact Information
P.O. Box 400
Linden, Michigan 48451 : :
: Jacob_Beningo
: Beningo Engineering
: JacobBeningo
: Embedded Basics
Jacob Beningo
Principal Consultant
© All Images and content in this presentation may not be used or copied without express written permission of the owner.