Presentation covers Embedded Linux systems basics including hardware, software and architectural concepts. Yocto, Raspberry Pi, Electronics Hardware, and Embedded Architecture.

1. Embedded Linux Systems Basics
-What it is and when to use it
-Pro/con consideration
-System architectures
-Physical platforms
-Custom distributions: Yocto
-Demo with uSOM (SSH via USB, GPIO,
streaming images, Bash scripting)

2. What It Is
● A miniature computer (with operating system)
running in an embedded device
● Runs a flavor of linux (generally custom)
● Allows applications level code to be utilized in
an embedded device setting
● Easily obtain: High definition displays (HDMI),
good sound, internet connectivity (wifi /
Ethernet), file transfer (USB), consumer
computer connectivity (SSH, bluetooth etc.)

3. When To Use It
● Want to make something with a high degree of
connectivity / computer like qualities but also
want it to interact with the physical world?
● Any system with a high degree of “human
interface” or data manipulation requirements
that can not be implemented on a smart phone,
web interface, or computer application alone is
a candidate.
● Want to use the abstraction and development
speed of Python in an embedded setting?

4. Good Candidates

5. Probably Not A Good Idea
Flight Controls

6. Pros
● Abstraction through applications level code (massive
improvements in development time)
● Easy internet connectivity (wifi, ethernet)
● Powerful data manipulation
● Low development time to achieve big wow factor:
pretty screens / sounds etc.
● Ability to interact with the physical world (motors,
valves, lights) without having to deeply understand
“bare metal” embedded C
● Your gateway to building“Internet of Things” devices
● Can publish code updates to all devices via the
internet

7. Cons
● Safety critical / very high reliability applications: 99%+ of the code on
your device you did not write, can you guarantee its functionality?
● Significant amount of power is required (Example: R Pi is ~4W).
Presents challenges for low power /battery operated devices
● Cost: about 25USD minimum (up to 120USD) for embedded
computer board
● Regulatory agency: Whats in your code? You - “I don't know but it
works”.
● Boot time is ~45secounds. How is screen activated during booting?
How do you respond instantly to a button press when in a sleep
state?
● Tight timing requirements: difficult / impossible to achieve timing
accuracy and speeds commonly seen in embedded C and RTOS
● Heat generation can be significant in an enclosed product
● Team needed: Hardware, software, firmware skills
● If using an off the shelf embedded computer, your ability to produce
relies heavily on your supplier – what if they make a mistake / stop
producing?

8. Simple Architecture

9. Parallel Architecture

10. Physical Platforms
● Raspberry Pi Compute Module
● $25USD
● Can use Raspbian Jessie Lite image for a start
https://www.raspberrypi.org/downloads/raspbian/
● https://www.raspberrypi.org/blog/raspberry-pi-compute-module-new-product/

11. Physical Platforms Continued
● BeagleBone Black
● SSH over USB
● $55USD
● Debian Linux Image
● https://www.adafruit.com/products/1996

12. Physical Platforms Continued
● Solidrun uSOM
● Wifi, SSH over USB
● $70USD
● https://www.solid-run.com/product/microsom-i2/

13. Custom Physical Platform
● Huge sustainment, cost and design “elegance”
advantages
● Get ready to spend a lot of time with Yocto
● Clementine Core is probably a good place to
start (has image to start working with)
http://circuitmaker.com/Projects/Details/Jay-Carlson-
2/Clementine-Core
● IMX6 Processor series from Freescale

14. What about Hardware?
● Remember: to pull this off we need hardware,
software, and firmware knowledge.
● Geppetto for basic carrier board designs
(2kUSD for a board)
● https://geppetto.gumstix.com/#!/

15. Yocto
● Why do you want a custom linux distribution?
● Set pin map and pin default state via layer
● Define drivers for peripherals such as wifi chip
sets
● Allows for smaller, more controlled and reliable
code base
● Builds can take several hours
● To quote a fellow engineer - “It's all very
magical but it seems to work...”

16. Yocto Resources
● Good place to start: build an image for
Raspberry Pi
http://www.jumpnowtek.com/rpi/Raspberry-Pi-Systems-with-Yocto.html
● Good book: https://www.amazon.com/Embedded-Systems-
Prentice-Software-Development/dp/0133443248
● https://www.yoctoproject.org/downloads
● https://www.yoctoproject.org/sites/default/files/y
pdd-2016.04-san_diego_1.pdf

17. Demo