The document discusses democratizing Internet of Things (IoT) development for all developers, detailing personal experiences and hardware setups, including a Raspberry Pi starter kit. It provides technical insights into accessing GPIO (General Purpose Input/Output) from Linux-based systems and demonstrates how to control pins through the Linux GPIO sysfs interface. Additional resources for further reading on Raspberry Pi and similar platforms are included along with contact information.

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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.

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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

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It’s All In The File System
 Linux GPIO Sysfs Interface for Userspace
 Root directory is at /sys/class/gpio
 Control Interfaces
 Pin Interfaces

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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

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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

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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

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Demo Time

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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

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