ppt on moving msg display

7/29/2019 ppt on moving msg display

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REAL TIME PROCESSING

WITH RTOS PORTING ON ARM

PROCESSOR

Student: S.D. Mali

Guide: Prof. Dr.A.D.Jadhav


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Contents

Introduction Block diagram of system

Block diagram details

Design of the system flow

System Design

Experimentation

Result and conclusion

References

Publications


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INTRODUCTION

Real-Time Systems Concepts

-Real-time systems are characterized by the fact that severeconsequences will result if logical as well as timing correctness

properties of the system are not met.

There are two types of real-time systems: SOFT and HARD.

In a SOFT real-time system, tasks are performed by the system as fastas possible, but the tasks don't have to finish by specific times.

In HARD real-time systems, tasks have to be performed not onlycorrectly but on time.

Most real-time systems have a combination of SOFT and HARDrequirements.


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Most applications for real-time systems are embedded.

Examples of embedded systems are:

Process control: Food processing, Chemical plants.

Automotive: Engine controls, Anti-lock braking systems.

Office automation: FAX machines, Copiers.

Computer peripherals: Printers, Terminals, Scanners,Modems,Robots.

Aerospace: Flight management systems, Weapons systems, Jet

engine controls.

Domestic: Microwave ovens, Dishwashers, Washing machines.


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BLOCK DIAGRAM OF SYSTEM

Hardware

RTOS

Application

Software

Fig.1. BLOCK DIAGRAM OF SYSTEM


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Block Diagram Details

The block diagram consisting three main parts:

RTOS

Hardware

Application Software

Basic Concept of RTOS:

RTOS is real time operating system . It is not necessary in small embedded systems. But it is

necessary in system where scheduling of multiple tasks,ISRs ,devices is important with respect to real time

constraints.


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Operating system that provides the most basic services to

application software running on a processor.

Fig. 2. Basic Services Provided by a Real-Time Operating System.


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Hardware

ARM7-2148 board with LED , Serial port, (16x2Text)LCD and (4X4 matrix)Keyboard.

Features of LPC2148 processor:

- 16/32-bit ARM7TDMI-S microcontroller in a tiny

LQFP64 package.

- 40 kB of on-chip static RAM.- 512 kB of on-chip flash program memory.

- 128 bit wide interface/accelerator enables high speed 60

MHz operation.


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- In-System/In-Application Programming (ISP/IAP) viaon-chip boot-loader software.

- One or two (LPC2141/2 vs. LPC2144/6/8) 10-bit A/Dconverters provide a total of 6/14analog inputs, with

conversion times as low as 2.44 s per channel.- Single 10-bit D/A converter provides variable analog

output.

- Two 32-bit timers/external event counters. PWM unit

(six outputs) and watchdog.- Low power real-time clock with independent power and

dedicated 32 kHz clock input.

- Multiple serial interfaces including two UARTs.


Multitasking of LED, Serial Port, LCD and Keyboard.


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Design of the System Flow

BeginDevelopment

PortApplication

Port RTOS,

COS-IIResearch on

RTOS, COS-II

Configure

Compiler

Research on

Compiler

Research on

Application

Configure

Hardware

Integrate

Components

and download

Hex file

Testing

Fig.3. Design Flow


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System Design

RTOSScheduler :

The scheduler, also called as dispatcher, is the part of the

kernel which is responsible for determining which task will

run next and when.

Most real-time kernels are priority based; each task is

assigned a priority based on its importance.

Establishing the priority for each task is applicationspecific.

In a priority based kernel, control of the CPU will always

be given to the highest priority task ready to run.


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When the highest priority task gets the CPU, however,

it depends on the type ofscheduler used.

There are two types of schedulers:

non-preemptiveand preemptive.

Non-preemptive scheduling :

is also called cooperative multitasking.

An ISR can make a higher priority task ready to run but

the ISR always return to the interrupted task.


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The new higher priority task will gain control of the

CPU only when the current task voluntarily gives up the

CPU.

Low priority task

ISRISR makes

high

priority

task ready

High priority task

Low priority task

Relinquishes cpu

Fig.4. Non Preemptive scheduling


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Preemptive scheduling :Low priority task

ISR

ISR makes high

priority task ready

High priority task

relinquishes cpu

High

priority

task

Fig.5. Preemptive scheduling


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when an event makes a higher priority task readyto run, the current task is immediately suspendedand the higher priority task is given control of theCPU.

Most real-time systems employ preemptiveschedulers because they are more responsive.

RTOS,COS-II is chosen here because it haspreemptive scheduler.

And also has many more features:Source code: is available free for non commercial

use and is well documented that it describes how

it works.


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Portable: is written in highly portable ANSI C. Target

processor code is in assembly language, purposely kept

minimum to make it easy to port on any processor.

ROMable: designed for embedded applications. if we

have proper tool chain (i.e. C compiler, assembler and

linker/locator) then we can embed it as a part of product.

Scalable: We can use only the services that we need inour application. This allows us to reduce the amount of

memory (both RAM and ROM) needed by C/OS-II.

Scalability is accomplished with the use of conditional

compilation. You simply specify (through #defineconstants) which features you need for your application.


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Preemptive: is a fully-preemptive real-time kernel. This

means that C/OS-II always runs the highest priority task

that is ready.

Multi-tasking: can manage up to 64 tasks, however, thecurrent version of the software reserves eight (8) of these

tasks for system use.56 tasks leaves for application. There

are thus 64 priority levels.

Deterministic: Execution time of all C/OS-II functions and

services are deterministic.

Task stacks: Each task requires its own stack, however,

C/OS-II allows each task to have a different stack size.This allows you to reduce the amount of RAM needed in

your application.

S i id b f i h


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Services: provides a number of system services suchas mailboxes, queues, semaphores, fixed-sizedmemory partitions, time related functions, etc.

Interrupt Management: Interrupts can suspend theexecution of a task and, if a higher priority task isawakened as a result of the interrupt, the

highest priority task will run as soon as all nestedinterrupts complete. Interrupts can be nested up to255 levels deep.

Robust and reliable: C/OS-II is based on C/OS

which has been used in hundreds of commercialapplications since 1992 and uses the same core andmost of the same functions as C/OS yet offers

more features.


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Port RTOS, COS-II:

Adapting RTOS to any processor is known as RTOS

porting.Application Software

COS-II(Processor Independent Code)

os_core.c,os_flag.c,

os_mbox.c,os_mutex.c,

os_q.c,os_sem.cos_task.c,os_time.c,

ucos-ii.c,ucos-ii.h

TimerCPU

COS-II Conf.(Application Specific Code)

os_cfg.h

includes.h

COS-II Port(Processor Specific Code)

os_cpu.h

os_cpu_c.cos_cpu_a.S

Software

---------------------------------------------------------------------------------------

Hardware

Fig.6. COS-II, Hardware/Software Architecture


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Fig. shows, COS-II file structure.

Kernel code is organized in three segments.

Application Specific Code: Contains user specific application software as well as some

code related to COS-II.

This includes initializing and starting the kernel and kernel

specific code for task management, synchronization andcommunication.

Processor Independent Code:

Is main code of COS-II. Is independent of actual target processor.

It provides kernel services for task management, timemanagement, semaphores, scheduling policy and memory

management.


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Processor Specific Code:

Contains an adaptation layer: port to the selected

target processor. This code typically manipulates directly individual

processor registers. e.g. In order to switch context.


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For porting RTOS, COS-II:

Application Specific Code:

includes.h:

-is a master file, found at the top of all .c files.-it allows every .c file in the project to be written

without concerns about which header file actually

needed./*MASTER INCLUDE FILE*/

#include

#include

#include

#include #include

#include

#include

#include "lpc21xx.h"


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os_cfg.h:

-is COS-II Configuration File.

-Using this file we simply specify (through #define

constants) which feature we need in our application.

/* COS-II Configuration File*/

#ifndef OS_CFG_H

#define OS_CFG_H

/* TASK MANAGEMENT */

#define OS_TASK_CHANGE_PRIO_EN 1 /* Include code for OSTaskChangePrio() */

#define OS_TASK_CREATE_EN 1 /* Include code for OSTaskCreate() */

#define OS_TASK_CREATE_EXT_EN 1 /* Include code for OSTaskCreateExt() */

#define OS_TASK_DEL_EN 1 /* Include code for OSTaskDel() */

#define OS_TASK_NAME_SIZE 32 /* Determine the size of a task name */

#define OS_TASK_PROFILE_EN 1 /* Include variables in OS_TCB for profiling */

#define OS_TASK_QUERY_EN 1 /* Include code for OSTaskQuery() */#define OS_TASK_SUSPEND_EN 1 /* Include code for OSTaskSuspend() and

OSTaskResume() */

#define OS_TASK_SW_HOOK_EN 1 /* Include code for OSTaskSwHook() */


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/* TIME MANAGEMENT */#define OS_TIME_DLY_HMSM_EN 1 /* Include code for OSTimeDlyHMSM() */

#define OS_TIME_DLY_RESUME_EN 0 /* Include code for OSTimeDlyResume() */

#define OS_TIME_GET_SET_EN 1 /* Include code for OSTimeGet() and

OSTimeSet() */

#define OS_TIME_TICK_HOOK_EN 1 /* Include code for OSTimeTickHook() */

#endif


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Processor Specific Code:

os_cpu.h:

OS_CPU.H contains processor andimplementation specific #defines constants,

macros, and typedefs.

os_cpu_a.asm:

A C/OS-II port requires that need to write four

assembly language functions:

OSStartHighRdy (), OSCtxSw (), OSIntCtxSw (),OSTickISR ()

OSStartHighRdy (): This is used to start multitasking.

This function is called by OSStart () to start the

highest priority task ready-to-run.

OSCtxSw():


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OSCtxSw():

This is used for task level context switch.

This function is executed when an interrupt is

encountered.C/OS-II causes a higher priority task to be ready-to-run.

The job of OSCtxSw() is to save the current taskcontext, switch over to higher priority task and then

restore context.The code saves current tasks registers onto its stack;

content of the link register is saved to both the linkregister and the program counter locations on the

stack.The task stack pointer is then saved to its task control

block, OSTaskSwHook() function is called, the higherpriority task stack is loaded, and the context of higher

priority task is restored.

OSIntCtxSw():


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OSIntCtxSw():

This is used for interrupt level context switch.

This function is called by OSIntExit() to perform a

context switch from an ISR, it is assumed that all theprocessor registers are already properly saved onto

the interrupted tasks stack.

The interrupt level context switch code is similar to thetask level context switch, except that the ISR has

already done the work of saving the processor context

the task stack.

OSTickISR ():C/OS-II requires that you should provide a periodic

time source to keep track on time delays and timeouts.

os cpu c c:


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os_cpu_c.c:

COS-II port requires that you write six fairly simple C

functions: OSTaskStkInit(), OSTaskCreateHook(),

OSTaskDelHook(), OSTaskSwHook(),OSTaskStatHook(), OSTimeTickHook().

The only function that is actually necessary is

OSTaskStkInit(). The other five functions must be

declared but theres no need to contain any code

inside them. OSTaskStkInit() function is called by

OSTaskCreate() and OSTaskCreateExt() to initialize

the stack frame of a task.

Processor Independent Code


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Processor Independent Code

As per the earlier discussion, processorindependent code is the main code of COS-II.

This code is independent of actual targetprocessor. Thus, this code need not to be changed;only it is required to be include in the project.

It provides kernel services for task management,

time management, semaphores, scheduling policyand memory management


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For Porting Application:


-it consists multitasking of three tasks

Task 1: LED ON/OFF.

Task 2: Print Character through Serial Port.

Task3: Display key code on LCD display.

-Each task is created with following function.

OSTaskCreate (void (*task)(void *pd), void *pdata,

OS_STK *ptos, INT8U prio)


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OSTaskCreate() requires four arguments.

taskis a pointer to the task code,

pdata is a pointer to an argument that will be passed to yourtask

when it starts executing, ptos is a pointer to the top of the

stack that will be assigned to the task(Task Stacks) and

finally, prio is the desired task priority.

For Example:

OS_STK Task1Stk[1024];

OSTaskCreate(App_Task1,(void*)0,&Task1Stk[1023],6);

D l ti d d fi iti f T k


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Declaration and definition of Task:

-Every task must be written as infinite loop

void App_Task1 (void *pdata); /* Declaration of Task */

void App_Task1 (void *pdata) /* Task Definition */

{

(void)pdata;

IO0DIR |= 0x00004000 ; /* IO Direction as Output*/

while(1)

{

IO0CLR = (1


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Delaying a task, OSTimeDlyHMSM()

We can specify time in hours (H), minutes (M),seconds (S) and milliseconds (M) which is morenatural.

Calling this function causes a context switch andforces C/OS-II to execute the next highest

priority task that is ready-to-run. The task callingOSTimeDlyHMSM() will be made ready-to-runas soon as the time specified expires.

This is the way there is context switch betweenall three tasks and multitasking is observed for allthree tasks.


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Compilation and Downloading procedure:

All required files from application specific code,processor specific code, processor independent code

and application software code are copied on singlefolder.

New project is created using the ARM specific crosscompiler (SCARM-IDE).

The makefile is edited for writing path of the folderthat is working directory. Then makefile is linked withthe project in the compiler (SCARM-IDE) with projectsetting option.

Then the code is compiled using build project option,this will generate hex file of project.

This hex file is downloaded on ARM7 LPC2148Board through Flash magic utility


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Fig.7. Downloading the Hex file on LPC 2148 Processor

E i t l S t


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ExperimentalSetup:

Power Supply

Computer

LCD Display

Keyboard

LPC2148

Fig.8. Experimental Setup

Results:


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Results:

1) LED becoming ON and OFF for 500ms.

2)Output on Flash magic Terminal through serial portfor every 600ms.

Fig.9. Output on Flash magic Terminal through serial port


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3)Displays key code on LCD whenever user press key

from (4X4) matrix keyboard.

LCD Displays

Key code Fig.10. LCD output


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Conclusion:

Thus the use of COS-II for multitasking, met timingcorrectness.

Preemptive scheduler in COS-II makes the real time

system more responsive.

THUMB code provide up to 65% of the code size of

ARM, and 160% of the performance of an equivalent

ARM processor connected to a 16-bit memory system.

Poorly designed and configured software architecturesmight even generate high response times while the

physical resources display low utilization.


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References:[1] V.Billy Rakesh Roy, Sanket Dessai, and S. G.Shiva Prasad Yadav, Design and

Development of ARM Processor Based Web Server, International Journal of Recent

Trends in Engineering, Vol. 1, No. 4, May 2009.

[2] Jean J. Labrosse, MicroC/OS-II The real time kernel, R &D Publications,

second edition, 1992.

[3] http://www.uCOS-II.com

[4] http://www.semiconductors.philips.com, http://www.arm.com, datasheet for

LPC2148..

[5] http://www.micrium.com, C/OS-II and The ARM Processor, Application Note,

AN-1011 Rev. D.

[6] Gunar Schirner, Gautam Sachdeva, Andreas gerstlauer, Rainer Domer,

Modeling, Simulation and Synthesis in an Embedded software design flow for ARM

processor, University of California, Irvine, Irvine, (A92697-3425, USA,

http://www.cecs.uci.edu[7] D.W.Hawkins, ([email protected]), Real time processing with the Philips

LPC ARM microcontroller using GCC and the MicroC/OS-II RTOS , Philips 05:

Project Number AR1803.
http://www.semiconductors.philips.com/http://www.arm.com/http://www.micrium.com/http://www.cecs.uci/mailto:[email protected]:[email protected]://www.cecs.uci/http://www.micrium.com/http://www.arm.com/http://www.semiconductors.philips.com/


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Publications:1) S.D.Mali, Dr.A.D.Jadhav Porting RTOS on ARM and Implementation of ARM

based Web Server, IEEE sponsored National Conference on Pervasive

Computing2010, Sinhgad college of Engineering, Pune.

2) S.D.Mali, Embedded Web Server using RTOS Porting on ARM Processor, 4th

National Conference on Recent Trends in Communication, Electronics &

Information Technology, CMRIT, Bangalore.

3) S.D.Mali, Dr.A.D.Jadhav Porting RTOS on ARM and Implementation of ARMbased Web Server, ePGCON-2010, Rajashri College of Engineering, Thathwade,

Pune & University of Pune.


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THANK YOU

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