embedded system introduction, build process, types,characteristics

1. Embedded Systems -
Introduction
By,
Mrs.S.Revathi

2. UNIT I
INTRODUCTION TO EMBEDDED SYSTEMS
• Introduction to Embedded Systems
• The build process for embedded systems
• Structural units in Embedded processor
• selection of processor & memory devices
• DMA
• Memory management methods
• Timer and Counting devices
• Watchdog Timer
• Real Time Clock
• In circuit emulator
• Target Hardware Debugging

3. Definition
“An embedded system is a system that has embedded
software in a computer hardware. The system is
dedicated for either an application(s) or specific part of
an application or product or a component of a large
system.”

4. Components
• It embeds hardware similar to a computer. the processer may
be embedded processor cores. The hardware includes
embedded memory, peripheral and input-output devices. It
embeds main application software which may perform
concurrently multiple tasks.
• Software usually embeds in the ROM, flash memory or media
card. Does not have secondary hard disk or CD memory as in
computer.
• It embeds real time operating system(RTOS). It supervises the
application software and controls the access to system
resources.

6. Characteristics
• Program is preloaded or embedded in the ROM or flash
memory.
• System functions in real time.
• Task executes according to priorities.
• The system reacts to the events, interrupts in predetermined
time interval and schedules responses according to priorities.
• System controls the latencies of tasks, events and then
interrupts and responds.
• Latency means time interval between the instance of need to
respond and start of the actual execution.
• Dedicated set of functions
• Complex dedicated –purpose algorithms
• Complex dedicated –purpose preprogrammed hardware and
graphic and other user interfaces
• Multirate operations with different predetermined time
constraints, to finish the different operations.

7. Constraints
• Available system memory
• Available processor speed
• Requirement for the system to run continuously and
therefore, the system needs to limit power dissipation
while running
• System design for an embedded system has
constraints of performance, power, size and the
design and manufacturing costs.

8. Processor embedded into a system
• Processor is an important unit in any computing
system
• It is the heart of the embedded system
• The instructions, defined in the instrument set of a
processor, arrange in a sequence in a program.
• The program executes in the sequence of their fetch
from the memory.
• Processor has two essential units: Program Flow
Control Unit and Execution unit
• The processor runs the cycles of fetch and execution
of a set of instructions.

9. Processor chip or core in an embedded system can be
one of the following:
• Microprocessor (or) Embedded Processor
• Application Specific Instruction-Set Processor (ASIP)
• Single-Purpose Processor as an Additional Processor

10. Build Process for Embedded Systems
• An embedded system develops using process of
designing the hardware, target platform and
software followed by integrating both.
• The first step in the build process for an embedded
system hardware consists of selecting a processor.
• A processor is selected from the considerations of
the following:
Instruction set
Maximum bits in an operand in a single arithmetic
or logical expression

11. Clock frequency in MHz or GHz and processing speed
in Million Instructions Per Second (MIPS)
Processing ability to solve the complex algorithm
using in meeting the deadlines for their processing.
• The build process for embedding software consists of
the following steps:
1. Project file consisting of source file and library files
2. Compilation of the project files
3. Linking all object files and locating onto a single re-
locatable object file
4. Converting the object file in a form called hex-file to
binary image (ROM image)

12. Build Process---Process
Embedding Microprocessor– Each microprocessor has
an instruction set. Programs written in high-level
language are compiled. A compiler generates the
executable codes. Executable code file loads into RAM
and runs using the processor.

13. • Embedding Microcontroller—Each microcontroller
has an instruction set which includes instructions,
which enable use of the devices and peripherals.
Programs are compiled. Embedded software actions
are simulated. The system software is debugged to
trace the errors. Flash is programmed using the tested
codes.

14. Embedded Hardware units and devices in a System
Building Blocks:
 Power Source
 Clock Oscillator and Clocking units
 System timer
 Real Time Clock
 Reset circuit, Power-up Reset and Watchdog-timer reset
 Memory
 Input, output and I/O ports, I/O buses and I/O interfaces
 Bus
 DAC
 ADC
 LED,LCD and Touch-Screen Displays
 Keyboard, keypad or virtual keypad at touch screen
 Interrupt handler

15. THANK YOU…