Learn how to build real Internet of Things (IoT) applications with pure Python and General Purpose Input/Output (GPIO). Thanks to devices like the Raspberry Pi and Intel Edison, full Linux systems with GPIO are accessible to the masses. Learn how build a true IoT device using only hardware and core Python libraries and hardware costing less than $50 US.

1. GOT PYTHON I/O
IOT DEVELOPMENT IN PYTHON VIA GPIO

2. HISTORICAL PERSPECTIVE
HOW I CAME UP WITH THE HAIR-BRAINED IDEA TO USE PYTHON FOR IOT

3. NODEBOTS DAY
Put on by Suz Hinton and Pawel
Szymczykowski

4. THE LEXICUTIONER
Designed a built using SumoBot Jr.
(Pawelbot) by Adam Englander and Lexi
Glazer

5. PHYSICAL ACCESS SYSTEM
Comprised of Raspberry Pi B, power
converter, electronic door latch, inline
switch. Software is Raspbian with Python
2.7 and Twisted.

6. PYTHON IOT STARTER KIT
RASPBERRY PI FOR THE WIN

7. STARTER KIT HARDWARE
• Raspberry Pi
• Micro USB with AC converter for power
• Cat 5 network cable
• USB Keyboard
• HDMI cable
• HDMI capable display – not shown
• 3.3V LED with (2) female to female connectors

8. STARTER KIT SOFTWARE
• Raspbian
• Pre-installed on SD card
• Download installer (requires SD card reader):
https://www.raspberrypi.org/downloads/
• Python 2.7
• Pre-installed on Raspbian

9. ACCESSING GPIO FROM LINUX BASED SYSTEMS
IT’S SO EASY YOU WON’T BELIEVE IT

10. GENERAL PURPOSE INPUT/OUTPUT (GPIO)
• A generic pin on an integrated circuit (IC) whose
behavior is controlled at runtime
• Use to control and transfer data to and from
external devices to the IC
• Available on all general purpose IC boards

11. IT’S ALL IN THE FILE SYSTEM
• Linux GPIO Sysfs Interface for Userspace
• Root directory is at /sys/class/gpio
• Control Interfaces
• Pin Interfaces

12. CONTROL INTERFACE
• “export” creates a node to expose a GPIO port
to the user space
• “echo 18 > /sys/class/gpio/export” will create a
gpio18 node at “/sys/class/gpio/gpio18”
• “unexport” removes the node for a GPIO port
from the user space
• “echo 18 > /sys/class/gpio/unexport” removes
the gpio18 node

13. GPIO SIGNALS
• “direction” determines the direction of a pin. Valid
values are “in” and “out”. “in” is used for interrupts
• “echo out > /sys/class/gpio/gpio18/direction” will
set GPIO pin 18 ’s direction as out
• “value” is the value of a pin. It reads a “0” or “1”.
Any on-zero value written will be interpreted as
“1”. When reading the value ”high” evaluates to ”1”
and “low” evaluates to “0” unless overridden by
“active_low”
• “echo 1 > /sys/class/gpio/gpio18/value” sets the
value of GPIO 18 to “1” and closes the circuit
• “cat /sys/class/gpio/gpio18/value” would return “1”
after the statement above

14. GPIO SIGNALS CONTINUED
• “edge” is used to tell the GPIO when to write to
”value” when “direction” is “in”. Valid values are
“none”, “rising”, ”falling”, and “both”.
• “echo both > sys/class/gpio/gpio18/edge” will
trigger an interrupt when voltage increases or
decreases
• “active_low” is used to invert the effect of
“edge” of “value”. Valid values are “1`” and “0”.
“1” inverts and “0” sets standard.
• “echo 1> sys/class/gpio/gpio18/active_low” will
invert the values of high and low

15. PYTHON ACCESS TO GPIO
CAT SKINNING 101

16. USE FILE SYSTEM ACCESS
• ”open”
• “read”
• “write”

17. TWISTED
• Event loop
• Single thread
• Asynchronous I/O
• HTTP server
• Websocket server
• File system I/O
• Real IoT

18. DEMO TIME

19. PLATFORM COMPARISON
HOW TO PICK THROUGH THE MYRIAD OF OPTIONS

20. RASPBERRY PI
Pros
• Moderately Inexpensive (~35 USD)
• Flexible platform
• Lots of guides and tutorials
• GUI interface for beginners
• Aptitude package manager
• Great starter platform
Cons
• Requires special cable to do away with keyboard
and monitor
• Under powered
• No built in Analog to Digital Converter (ADC)
• A bit on the large side
• ARM processor

21. INTEL EDISON
Pros
• X86 based Atom processor
• Ample power, RAM, and storage
• Multiple form factors
• Arduino developer board can use standard
Arduino backplanes
• Easy to setup Wi-Fi
• Arduino board has Analog to Digital Converter
and Python library
Cons
• Can be a bit pricy (~110 USD)
• Not as many guides and tutorials
• Documentation is a bit confusing at times
• Evolving platform
• Sysfs GPIO is flakey

22. DRONESMITH LUCI
Pros
• Easy to build unmanned vehicles
• No real electrical understanding needed
• Just uses some simple scripting
• Based on Intel Edison
Cons
• Expensive
• Still in early development phase
• No real direct development – just scripting
routes.

23. CHIP
Pros
• Super inexpensive (~10 USD)
• Wi-Fi
• Bluetooth
Cons
• Low power
• Pre-order only

24. BEAGLEBONE BLACK
Pros
• Inexpensive (~50 USD)
• Can be a full computer
• Has add-on ecosystem
• Lots of connectivity
• On-board Analog to Digital Converter (ADC)
Cons
• Low power
• ARM chipset

25. FURTHER READING
• Raspberry Pi: https://www.raspberrypi.org/
• Linux Kernel GPIO Sysfs: https://www.kernel.org/doc/Documentation/gpio/sysfs.txt
• Examples for GPIO in Bash and PHP: https://github.com/aenglander/iot-examples
• Twisted: http://twistedmatrix.com/
• Intel Edison: http://www.intel.com/content/www/us/en/do-it-yourself/edison.html
• CHIP: https://getchip.com/pages/chip
• Luci: http://www.dronesmith.io/luci/

26. CONTACT INFO
• @adam_englander on Twitter
• adam@launchkey.com
• aenglander on Freenode
• aenglander on GitHub
• adamenglander on Linkedn