The document discusses the embedded configurable operating system (eCOS) which is an open-source operating system ideal for embedded systems development. eCOS has a small memory footprint and is highly configurable. It discusses the kernel design which aims for low latency, small memory footprint, and deterministic behavior. Key kernel features include threading, scheduling, synchronization, interrupt handling and exception handling. The document also summarizes eCOS support for interrupts, I/O, memory management, multitasking, file systems, networking, security and user interfaces. It compares the memory requirements of eCOS to general purpose and other event-driven operating systems.

1. EMBEDDED CONFIGURABLE
OPERATING SYSTEM (eCOS)
By
Misheal Ayaz
Shehla Afzal

2. What is an Embedded OS
• An "embedded system" is any computer system or
computing device that performs a dedicated function or is
designed for use with a specific embedded software
application.
• Often, embedded systems are part of a larger system or
product,
e.g., antilock braking system in a car

3. Embedded Configurable Operating
System
ECOS is an open-source, royalty-free
(http://en.wikipedia.org/wiki/Royalty-free),
highly configurable, application-specific
operating system ideal for embedded systems
development. eCos is targeted at high-volume
applications in consumer electronics,
telecommunications, automotive, and other
deeply embedded applications.

4. Diagram
The eCos Layered Software Architecture

5. Kernel Design
The eCos kernel was designed to satisfy four main objectives
1)Low interrupt latency
The time it takes to respond to an interrupt
2)Low task switching latency
The time it takes from when a thread becomes available to when actual
execution begins
3)Small memory footprint
Memory resources for both program and data are kept to a minimum by
allowing all components to configure memory as needed
4)Deterministic behavior
Throughout all aspect of execution, the kernels performance must be
predictable and bounded to meet real-time application requirements

6. Kernel Features
The following is a partial list of kernel features:
• eCos kernel provides the core functionality needed for
developing multi-threaded applications
- create and control threads
- scheduling, e.g., multilevel queue
- synchronization, e.g., semaphores
• Some not included to make for a small kernel
- memory allocation (in separate package)
- device drivers (in separate packages)
• interrupt handling
• exception handling
• cache control
• trace buffers
•infrastructure and instrumentation

7. Good Embedded OS
• Small footprint
• Configurable
• Open Source
• Hardware Supported
• Device drivers

8. Interrupts
Create Interrupts
Delete Interrupts
Attach/Detach Interrupts
Configure Interrupts
Acknowledge Interrupts
Enable ?disable Interrupts

9. I/O
Packages for all generic hardware independent I/O system
support
•Ethernet
•Flash
•serial which is basic for system device drivers.

10. Memory Management
eCos is a single process, multiple thread operating
environment. As such, memory management is
not required. Memory management hardware
may be used on some platforms where it exists
and is required for optimum performance. For
example, on PowerPC based platforms, memory
management is used in order to enable cache
operations.

11. Multitasking
Two threads with simple print statements after random delays

12. File System
Including FAT File system in a Configuration
The FAT file system is contained in a single eCos package,
CYGPKG_FS_FAT. However, it depends on the services of a
collection of other packages for complete functionality
• CYGPKG_IO_FILEIO
• CYGPKG_IO
• CYGPKG_IO_DISK
• CYGPKG_LINUX_COMPAT
• CYGPKG_LIBC_STRING
• CYGPKG_MEMALLOC
http://www.ecoscentric.com/ecospro/doc/html/ref/fatfs-config.html

13. Networking
TCP/IP (Transmission Control Protocol /
Internet Protocol) Stack Support for eCos
The Common Networking for eCos package
provides support for a complete TCP/IP
networking stack. The design allows for the
actual stack to be modular and at the current
time two different implementations, one
based on Open BSD from 2000 and a new
version based on FreeBSD, are available.

14. Security
 Maximum security against data theft and data
manipulation.
 ECOS Technology has specialized in the
development of high-security solutions for
mobile and remote access to data - Remote
Access.
 The system ecos secure is designed for the
secure management of keys in critical and
security relevant company sectors.

15. User Interface
User Interface task mainly provides two
functionalities
1)Display receiving information to User
2) Accept action request from User/Keyboard.

16. Comparison with other OSs
General purpose OS Event-driven OS
MOC Multi-tasking Communicating EFSMs
Generality General Target event driven systems
Communication Overhead Large Small
Communication Frequency Infrequent Frequent
Memory Requirement Large Small
General comparison
OS type Processor Application Total instruction mem Data mem
General Purpose ARM7 thumb 10,096 22324 54988
Event-driven ARM7 thumb 5312 8000 2800
Event-driven 8 bit RISC 2740 3176 709
Memory requirements comparison.

17. The End
Thank you