Learn how anyone can build IoT applications with any language that will run on Linux and can access the file system.

1. +
Democratizing IoT
Internet of Things Development for Every Developer

2. +
Historical Perspective
How I came up with the hair-brained idea that everyone could do IoT development

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. +
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/

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. +
Demo Time

16. +
Further Reading
 Raspberry Pi: https://www.raspberrypi.org/
 Intel Edison:
http://www.intel.com/content/www/us/en/do-
it-yourself/edison.html
 CHIP: https://getchip.com/pages/chip
 Tessel: https://tessel.io/
 Linux Kernel GPIO Sysfs:
https://www.kernel.org/doc/Documentation/
gpio/sysfs.txt

17. +
Contact Info
 @adam_englander on Twitter
 adam@launchkey.com
 aenglander on Freenode
 aenglander on GitHub
 adamenglander on Linkedn