ABSTRACT
ARM
is the industry's leading supplier of microprocessor technology, offering the
widest range of microprocessor cores to address the performance, power and cost
requirements for almost all application markets. The aim is to develop advanced
LPC1768 ARM processor without compromising the performance. RTOS with library
functions which can be accessed remotely adds advantage to this processor in
terms of efficiency, performance, memory, speed. In conventional processor there is no enough
memory to perform complicated algorithms and tasks in image processing such as
face recognition, fingerprint authentication, etc. In order to overcome this problem web
service is incorporated with this processor. A web service is any piece of
software that makes itself available over the internet. Web service includes a web server which handles standard library
functions and complicated functions like image processing functions. This will
provide easy access to the user who needs to perform complicated functions. With
the help of this web service time and memory consuming processes can be done in
am efficient manner.
INTRODUCTION
An operating system is a computer program that
supports a computer's basic functions, and provides services to other programs
that run on the computer. Most operating systems appear to allow multiple
programs to execute at the same time. This is called multi-tasking. In reality,
each processor core can only be running a single thread of execution at any
given point in time. A part of the operating system called the scheduler is
responsible for deciding which program to run when, and provides the illusion
of simultaneous execution by rapidly switching between each program. The type of an
operating system is defined by how the scheduler decides which program to run
when. For example, the scheduler used in a multi user operating system will
ensure each user gets a fair amount of the processing time. The scheduler in a
Real Time Operating System (RTOS) is designed to provide a predictable
execution pattern. This is particularly of interest to embedded systems as
embedded systems often have real time requirements. A real time requirement is
one that specifies that the embedded system must respond to a certain event
within a strictly defined time (the deadline).
Embedded
systems are not recognizable as computers. Instead, they are hidden inside
everyday objects that surround us and help us in our lives. Embedded systems
typically do not interface with the outside world through familiar personal
computer interface devices such as a mouse, keyboard and graphic user
interface. Instead, they interface with the outside world through unusual
interfaces such as sensors, actuators and specialized communication links.
Real-time and embedded systems operate in constrained environments in which
computer memory and processing power are limited. They often need to provide
their services within strict time deadlines to their users and to the
surrounding world. It is these memory, speed and timing constraints that
dictate the use of real-time operating systems in embedded software.
Real time embedded system with RTOS
The heart of a real-time OS (and the heart of every OS, for that
matter) is the kernel. A kernel is the central core of an operating
system, and it takes care of all the OS jobs. In an embedded system, frequently the kernel
will boot the system; initialize the ports and the global data items. Then, it
will start the scheduler and instantiate any hardware timers that need to be
started. After all that, the Kernel basically gets dumped out of memory, and
the scheduler will start running the child tasks. In this paper, advancement in processor is introduced in the
aspect of RTOS. In conventional processor RTOS handles only standard library
functions. This limits the performance of the processor. In order to enhance
the capability of the RTOS, complicated functions such as image processing
algorithms and tasks are made as functions and added to the function
library.
1.
Booting
2.
Task Scheduling
3.
Standard Function
Libraries + library handling complicated algorithms which can be accessed
remotely from web server.
User can perform complicated tasks by calling the
functions in the library. The input of the complicated task/algorithm should be
given as arguments of the function. The function definition is stored in the
webserver. By sending the function with arguments to the webserver through
GPRS, the user can perform desired operations. Webserver returns the output to the
RTOS in a specified format. Thus RTOS is responsible for providing specified
output to the user.
IMPLEMENTATION
LPC1768 is an ARM Cortex-M3
based microcontroller for embedded applications featuring a high level of
integration and low power consumption. The LPC1768/66/65/64 operates at CPU
frequencies of up to 100 MHz. The ARM Cortex-M3 CPU incorporates a 3-stage pipeline
and uses Harvard architecture with separate local instruction and data buses as
well as a third bus for peripherals. The ARM Cortex-M3 CPU also includes an
internal prefetch unit that supports speculative branching. The peripheral
complement of the LPC1768/66/65/64 includes up to 512 kB of flash memory, up to
64 kB of data memory, Ethernet MAC, USB Device/Host/OTG interface, 8-channel
general purpose DMA controller, 4 UARTs, 2 CAN channels, 2 SSP controllers, SPI
interface, 3 I2C-bus interfaces, 2-input plus 2-output I2S-bus interface,
8-channel 12-bit ADC, 10-bit DAC, motor control PWM, Quadrature Encoder
interface, 4 general purpose timers, 6-output general purpose PWM, ultra-low
power Real-Time Clock (RTC) with separate battery supply, and up to 70 general
purpose I/O pins. The LPC1768/66/65/64 are pin-compatible to the 100-pin
LPC236x ARM7-based microcontroller series.
Processor
The
RTOS of the introduced processor consists of specific functions to access
peripherals. In conventional processor user needs to write lengthy program to
access peripheral devices. This will reduce the complications in accessing the
peripherals. Input of the time consuming processes should be sent to the web
server which provides web services using GPRS. The
term web services describes a standardized way of integrating web based
applications using the HTML,AJAX,XML, SOAP, WSDL and UDDI open standards over
an internet protocol backbone. Now let us see how to access webserver function
and how to execute it in server side. Following program explains how to call FFT function which is in webserver
library.
Program to be handled by RTOS (to access web server):
#define freq 60
#define pi 3.14
struct function_args
{
//function
name
char *func_name;
//function
argument address collection
int function_arg[100];
//int,float,array
etc
int function_argtype[100]
//return
argument collection
int retun_arg[100];
//int,float,array
etc
int return_argtype[100];
};
main()
{
float res[100],sig[100];
int i;
struct function_args func_args;
static char *fname=”fft”;
for(i=0; i<100; i++)
{
//signal
generation for fft
sig[i]= 2* pi* freq* *(i/100);
}
func_args.func_name= f_name;
//assign
input signal to argument of FFT function
func_args.funcinon_arg[1]=sig;
// assign
argument type for FFT. Ex: 0x15 àfloating point array and 0x64 àbuffer size 100
func_args.function_argtype[1]= 0x6415;
//assign
address of result for FFT
func_args.return_arg[1]=res;
func_args.return_argtype[1]= 0x6415;
// inbuilt function in
RTOS which handles server through
TCP/IP or HTTP. Function name and function arguments are extracted by RTOS from
func_args structure and it is passed to the server and responses are stored
into the func_args structure
Remote Call( &func_args);
}
To perform FFT operation RTOS calls the function in webserver through TCP/IP or HTTP. Function name and
function arguments are extracted by RTOS from func_args structure and it is
passed to the server. After calling the FFT function which is in webserver, function
definition should be executed by the web server. To perform specific operation,
program should be written in server side. Following program explains how the
webserver should react if the user (RTOS) tried to access FFT function. The
result is sent to the RTOS using GPRS.
Server side program for php:
<?php
if(isset($_POST[‘func_name’])
{
$func_name=$_POST[‘func_name’];
If($func_name==’fft’)
{
$sig=$_POST[‘inp1];
$freq=$_POST[‘inp2];
//created in server
$res=fft($sig, $freq);
Echo $res;
}
//other functions
elseif .
.
.
}
echo ‘check syntax’;
?>
The above program which is written in php shows
the selection of FFT function among
various functions in webserver. Thus our proposed processor can be implemented
to overcome the problems such as performing complicated functions in the
context of memory and speed. Surely this processor will be the perfect
replacement for existing processors.
Download Full Paper
functions for Dynamic configured peripheral devices, visit to Library for ARM Device
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