1. Embedded systems
Lecture
25 February 2015

2. What does it mean: programming for an embedded system?

3. Definition of an embedded system:
Dedicated hardware and software,
designed to perform a specific task.

4. Dedicated hardware and software
Playing media, audio and video
TV signal decoding
Recording media (PVR = personal video recorder)
Low power consumption (energy saving)
Internet browsing
Communication with other devices: remote control, game pad, smartphone...

5. Dedicated hardware and software
CPU
RAM and ROM
Ethernet, WiFi
HDD
Tuner
Decoder
Display (TV)
Audio and video output (HDMI)

6. Dedicated hardware and software
Low level:
Memory mapping
Interrupts
Bootloader
Kernel and Kernel modules
File system
I/O
Drivers
Usually C languge

7. Dedicated hardware and software
Middleware - System logic to implement the „Dedicated” features,
.e.g:
Web servers/clients
PVR
Usually C++ language

8. Dedicated hardware and software
When hardware changes - drivers change.
To avoid middleware changes there is a
HAL = Hardware Abstraction Layer between Middleware and Drivers.
Middleware
HAL
Drivers
Hardware

9. Dedicated hardware and software
Browser
WebKit – open source engine
JavaScript and HTML5 support
Middleware
HAL
Drivers
Hardware

10. Dedicated hardware and software
SDK for application developement
Public API for JavaScript
Allows to launch user applications on embedded systems
Applications
JavaScript and HTML5
Browser
Middleware
HAL
Drivers
Hardware

11. WEB example – html5 video tag

12. WEB example – html5 video tag

13. How does Browser (WebKit) plays video tag?

14. How does Browser (WebKit) plays video tag?
You can also implement you custom interface in similar way

15. How does Browser (WebKit) plays video tag?
Custom interface implementations allow the use of custom hardware through Middleware/HAL
Browser (custom Webkit)
Middleware
HAL
Drivers
Hardware

16. Public API example : tuneUp function

17. Public API example : tuneUp function
Middleware implements API functions
In this example receives tuneUp request (channel change)
Applications
JavaScript and HTML5
Browser
Middleware
HAL
Drivers
Hardware

18. Public API example : tuneUp function
Middleware implements and manages the flow of channel change:
Tuner
Frequency to digital
Demultiplexer
Parses video from mpegts
Decoder
Video processing (de-noise, scaler)
Renderer
(display)

19. Other Middleware examples
Trickplay – fast forward video playing
File
I-frames indexer
Buffer
Decoder
Streaming video file to mobile device
File
Buffer
HTTP Server
...

20. So, what does it mean: programming for an embedded system?
In most cases it is programming for Middleware layer – sophisticated logics
Usually C++ programming in Linux
Threads, buffers, memory management, design patterns, network, shared libraries, open source components (e.g ffmpeg, Gstreamer)...
Low Level programming

21. So, what does it mean: programming for an embedded system?
Non-recurring engineering:
Middleware/Low level devolepement is expensive but once it is done it can be duplicated with NO cost
Choise of more expensive hardware component can cause HUGE cost increase!
Whenever possible it is always better to place logic in middleware level

22. Do you know an example of binding between JavaScript and C++?
Quiz
Do you know an example of binding between JavaScript and C++?
Remote Procedure Call (RPC)
How is it done in Facebook?
Applications
JavaScript and HTML5
Browser
Middleware
HAL
Drivers
Hardware

24. Thank you! a.kurek@samsung.com 4/17/2017
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