Embedded System Training - Day1

Embedded System Training - Day 1

A system is a way of working , organizing or doing one or many tasks

e.g.

Time display system.

Automatic Cloth Washing Machine : Wash by spinning a motor .

Computers Vs Embedded System

1)Combination of HW and SW.

2)Operating System manages many tasks at a time.

3)Combination of HW and SW which works towards specific goal is called embedded system.As a manufacturer, we clearly predict what embedded system is used for.

Optimally Designed HW and Dedicated Software and Firmware.

CPU sits on top of firmware , sensors and actuators communicate through them.

ES domains

a)Automotive

b)Aerospace

c)Livestock Management

d)Medical

Embedded Systems are not used for computation these days..

Real time system : A time constrained Embedded system.

Hard and Soft Real time systems.

Types of Developement

Native Developement : Desktop application and normal development.

Cross Development : Usage of two environment, host machine[PC] and Target [ where application gets executed]

Here the program executes in different machine and developement happens in different machines.

This interface between the Host and Target can be anything * [Doubt1]

Device corresponds to Data Sheet.ESD is all about Cross Development.

Components of embedded system :

System-On-Chip

1.Processor

2.Program Memory and Data Memory

[Memory is no more critical due to advancement in Memory technology]

3)Timers

4)Interrupt Controller

5)Parellel Ports

6)Serial Communication Port

7)Clock Generation Unit

8)Power Supply and Management

[Critical in all systems]

9)Output Interface

10)System Application Specific Circuits.

Power Source :

Systems may or may not have own power supply

digital watch

media player

System which do not have power supply

-- Network Interface card

-- Pen Drive

-- External Hard Disk.

Power Requirements :

-- 5.0V +/- 0.25V

-- 3.3V +/- 0.3V

-- 2.0V +/- 0.2V

-- 1.5V +/- 0.2V

Power Management :

-- Optimizing the code.

-- Enabling and Disabling Caches and Cache blocks

[High speed memory,bypassing accessing of Cache can save power]

-- Reduction of the clock rate during specific set of instruction.

Clock Oscillator and Clocking Units

-- of the cpu

-- of the system timers

-- Fetching codes and data,decoding and execution

Why exe needs to be moved from Secondary memory to RAM?

Processor is not capable : Harddisk is block addressible and RAM[primary memory] is byte addresible .Microcontrollers are Bit-addresible.Flash is Byte Addresible*[semi-conductor based-- Doubt2]

Reset Circuit

1)CPU begins the processing the instruction from a starting address.

2)Program which runs after reset on powerup

-- A system program that executes from the beginings

-- A system boot-up program

-- A system initialization program

3)Reset on WDT expiry.

Types of Memory:

--Internal and external RAM.

--Internal Caches

-- Flash EEPROM [ external or internal ]

-- ROM/PROM

-- NVRAM

ROM/EROM/FLASH

-- RTOS & Application program bundled together

-- Codes for System Booting/Initialization/Initial input data and strings.

-- Non-Volatile results for processing.

RAM[ Internal/ External / Buffer RAM]

-- Storing the code segment

-- Stack/Heap memory

NOR Flash : Kernel, Configuration data , hence protection is there.

NAND Flash :FS,Application,User Space.

Caches

-- copies of instruction/data and brance tranfer instruction .

Interrupt Handler

-- external port interrupt

-- IO interrupt

-- timer and RTC interrupt

-- SW interrupt

Design Process in ES

-- Abstraction

-- HW & SW Architecture

-- Extra functional properties

-- System related family of design [ Not valid much as embedded devices are very much different from each other]

-- Modular Design [ reusable ]

Design process contd....

-- UI design

-- Refinements

Developement Process

-- Model Analysis

-- Design SW architecture,interfaces and algorithms

-- Implementation of Design

-- Test Internal Logic and External Functions.

Design Metrics

-- Power dissipation

-- Performance

-- Process deadlines

-- User Interfaces [ IOS ]

-- Size : code and device both

-- Engineering Cost

-- Manufacturing Cost

-- Flexibility

-- Prototype

-- Development time

-- Time to Market

-- System and user safety

-- Maintenence

Challenges in ESD

-- Clock rate reduction

-- Voltage reduction

-- Wait , Stop and Cache disable functions

-- Process deadlines

-- Flexibility and upgrade ability

ROM image : Final stage of Software image

-- Just as an image in a unique sequence and arrangement of pixel

-- Embedded software must be placed in proper address.

-- Placed in Non-Volatile Memory

General Concepts :

Boot Loader is loaded through MBR.

Boot Loader loads the Operating System.

Basic GCC

gcc -e file.c ---> output to monitor

gcc -s file.c ---> .s file

gcc -c file.c ---> .o file

gcc -d INTEL file.c ---> conditional compilation using INTEL which defined externally.

Small Scale ES

-- Designed with a single 8 or 16 bit microcontroller

-- Little HW & SW complexities and involved board design.

Medium Scale ES

-- 16 bit or 32 bit micro controllers

-- DSP and RISC

Sophisticated ES

-- Enormous SW and HW complexities

-- Scalable and Configurable Processors

-- HW and SW co-design and component integrations in final stages.