(Approved by A.I.C.T.E.New Delhi & Affiliated to J.N.T.U.Hyderabad.

)
Beside Mount opera, Near Ramoji Film City,Hayath Nagar ,R.R.Dist.Hyderabad- 501512
A.P.

DEPARTMENT OF
ELECTRONICS AND COMMUNICATIONS
ENGINEERING
 ARJUN COLLEGE OF TECHNOLOGY AND SCIENCES
Beside Mount opera, Near Ramoji Film City,Hayath Nagar ,R.R.Dist.Hyderabad-
501512 A.P.

Lab Manual for the Academic Year 2012-13

SUBJECT : EMBEDDED SYSTEMS LAB I

SEMESTER : MTECH - ISEM

STREAM : EMBEDDED SYSTEM

INSTRUCTOR : UPENDAR SAPATI

PROGRAMMERS : BHARGAVA NAIDU

LAB I/C Head ECE

 INDEX

S.No Name of the Content PAGE NO.

1 Lab Objective 4

2 Introduction About Lab 5

3 LAB CODE 6

4 List of Lab Exercises 7

5 Description about ES Concepts 8

6 Programs List 9

7 References 52

-3-
Lab Objective:

An embedded system is some combination of computer hardware and

software, either fixed in capability or programmable, that is specifically designed for a
particular kind of application device. Industrial machines, automobiles, medical
equipment, cameras, household appliances, airplanes, vending machines, and toys (as
well as the more obvious cellular phone and PDA) are among the myriad possible
hosts of an embedded system. Embedded systems that are programmable are provided
with a programming interface, and embedded systems programming is a specialized
occupation.

An embedded system is a special-purpose computer system designed to

perform one or a few dedicated functions[1], often with real-time computing
constraints. It is usually embedded as part of a complete device including hardware
and mechanical parts. In contrast, a general-purpose computer, such as a personal
computer, can do many different tasks depending on programming. Embedded
systems have become very important today as they control many of the common
devices we use.

Since the embedded system is dedicated to specific tasks, design engineers can
optimize it, reducing the size and cost of the product, or increasing the reliability and
performance. Some embedded systems are mass-produced, benefiting from
economies of scale.

-4-
INTRODUCTION ABOUT LAB

There are 66 systems ( Compaq Presario ) installed in this Lab.

Their configurations are as follows :
Processor : AMD Athelon ™ 1.67 GHz
RAM : 256 MB
Hard Disk : 40 GB
Mouse : Optical Mouse
Network Interface card : Present

Software
1 All systems are configured in DUAL BOOT mode i.e, Students can boot from
Windows XP or Linux as per their lab requirement.
This is very useful for students because they are familiar with different
Operating Systems so that they can execute their programs in different
programming environments.
2 Each student has a separate login for database access
Oracle 9i client version is installed in all systems. On the server, account for
each student has been created.
This is very useful because students can save their work ( scenarios’,
pl/sql programs, data related projects ,etc) in their own accounts. Each student
work is safe and secure from other students.
3 Latest Technologies like DOT NET and J2EE are installed in some
systems. Before submitting their final project, they can start doing mini
project from 2nd year onwards.
4 MASM ( Macro Assembler ) is installed in all the systems
Students can execute their assembly language programs using MASM.
MASM is very useful students because when they execute their
programs they can see contents of Processor Registers and how each
instruction is being executed in the CPU.
1 Rational Rose Software is installed in some systems
Using this software, students can depict UML diagrams of their
projects.
2 Software installed : C, C++, JDK1.5, MASM, OFFICE-XP, J2EE and
DOT NET, Rational Rose.
3 Systems are provided for students in the 1:1 ratio.
4 Systems are assigned numbers and same system is allotted for students when
they do the lab.

-5-
LAB CODE

1. Students should report to the concerned labs as per time table schedule.
2. Students who turn up late to the labs will in no case be permited to do the
program scheduled for the day.
3. After completion of the program , certification of the concerned staff in-
charge in the observation book is necessary.
4. Students should bring a notebook of about 100 pages and should enter the
reading/observations into the notebook while performing the experiment.
5. The record of observations along with the detailed experimental procedure of
the experiment performed in the immediate last session should be submitted
and certified by the staff ember in-charge.
6. Not more than three students in a group are permitted to perform the
experiment on a setup.
7. The group-wise division made in the beginning should be adhered to and no
mix up student among different groups will be permitted later.
8. The components required pertaining to the experiment should be collected
from stores in-charge after duly filling in the requisition form.
9. When the experiment is completed, students should disconnect the setup
made by them, and should return all the components/instruments taken for the
purpose.
10. Any damage of the equipment or burn-out of components will be viewed
seriously either by putting penalty or by dismissing the total group of students
from the lab for the semester/year.
11. Students should be present in the labs for the total scheduled duration.
12. Students are required to prepare thoroughly to perform the experiment before
coming to Laboratory.
13. Procedure sheets/data sheets provided to the student’s groups should be
maintained neatly and to be returned after the experiment.

-6-
 List of Lab Excercises

EMBEDDED SYSTEMS – Lab Programs List

Submission – 1

1. Write a Program to
a). Read inputs from switches.
Week – 1
b). To make LEDs blink.

Week – 2 2. Write a Program for serial communication.

3. Write a Program for encruption / decruption.
Week – 3
4. Develop necessary interfacing circuit to read data from a sensor and
Week – 4
process using the 801 and 8051 boards. The data to be displayed on a PC monitor.

Submission – 2
Week – 5 5. Sort RTOs (mCOS) on to 89CS1 board and Verify.
Week – 6 6. Simulate on elevator movement using RTO’s on 89CSI board.

-7-
Description about ES Concepts:

Embedded systems are designed to do some specific task, rather than be a

general-purpose computer for multiple tasks. Some also have real-time
performance constraints that must be met, for reason such as safety and usability;
others may have low or no performance requirements,allowing the system
hardware to be simplified to reduce costs.

Embedded systems are not always separate devices. Most often they are
physically built-in to the devices they control.

The software written for embedded systems is often called firmware, and is
stored in read-only memory or Flash memory chips rather than a disk drive. It
often runs with limited computer hardware resources: small or no keyboard,
screen, and little memory.

Embedded systems range from no user interface at all — dedicated only to one
task — to full user interfaces similar to desktop operating systems in devices such
as
PDAs.
Simple embedded devices use buttons, LEDs, and small character- or
digit-only displays, often with a simple menu system.

-8-
1. Write a Program to
a) Read inputs from switches.
b) To make LEDs blink.

Aim:

To Read inputs from Switches

Program

8-Way DIP Switch

This is another simple interface, 8to the port lines, and for some control application
i) The Development board has one no. of 8used to provide digital inputs to the
microcontroller’s ports.
ii) User can change the level of digital inputs whatever they want, either high
or low by simply selecting the jumper+5V, in order to should be used.

-9-
/*---------------------------------------------------------------------
Example 1 : Read Switch status & displayed in LED’s
Description : Depends upon the dip switch position
the corresponding leds are on (or) off
Company : PANTECH SOLUTIONS PVT LTD
----------------------------------------------------------------------*/

FLOW Chart

- 10 -
CODE:

#include <reg51.h> //Define 8051 Registers

#define LED P0 //Assign led to P0
#define SWITCH P1 //Assign switch to P1

/************************** Main
Function*****************************/
void main(void)
{
SWITCH = 0xff; //Initialize the switch as input port
LED = 0x00; //Initialize the led as output port
while(1)
{
LED = ~SWITCH;
}
}

Execution:

Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 11 -
/*---------------------------------------------------------------------
Example 2 : Read Switch status & scrolling the LED’s
Description : Depends upon the dip switch position
the led will be scrolling
Company : PANTECH SOLUTIONS PVT LTD
----------------------------------------------------------------------*/

- 12 -
Code:

#include<reg51.h> //Define 8051 Registers

#define Led P0 //Assign led as P0
#define Switch P1 //Assign switch as P1
void DelayMs(unsigned int k); //Delay function
void scrollLeft();
void scrollRight();
int loop,port;

/************************** Main
Function*****************************/
void main(void)
{
Switch =0xff; //Intialize the port1
Led =0x00; //Intialize the port0
while(1)
{
if(Switch ==0xfe)
{ scrollLeft(); //scrollLeft function
}
else if(Switch ==0xfd)
{ scrollRight(); // scrollRight function
}
else
{ Led =0x00;
}
}
}

/*************************** Delay for 1 msec*************************/

void DelayMs(unsigned int k)
{
unsigned int i,ms;
for(ms=0;ms<=k;ms++)
{ for(i=0;i<=114;i++); }
}

/*************************** LED Scroll Left *************************/

void scrollLeft()
{
port=1;
for(loop=0;loop<8;loop++)
{
Led =port;
port=port*2;
DelayMs(500); //Delay for 500ms
}
}

- 13 -
/*************************** LED Scroll Left *************************/
void scrollRight()
{
port=128;
for(loop=0;loop<8;loop++)
{
Led =port;
port=port/2;
DelayMs(500); //Delay for 500ms
}
}

Execution:

Note: After loading corresponding Examples Hex file located in “OUT” Folder to
The microcontroller kit, press “RST” Button, user program now executes.

- 14 -
b) To make LEDs blink

----------------------------------------------------------------------*/
Example 1 : Program to Blink LED at P0.0
Description : Connect a LED at a port pin and make it
flash at predefined intervals.
Company : PANTECH SOLUTIONS PVT LTD
----------------------------------------------------------------------*/

Flow Chart

- 15 -
Code:

#include<reg51.h> //Define 8051 Registers

void DelayMs(unsigned int a); //Delay function
sbit led =P0^0; //Set bit P0^0 for led

/
*------------------------------------------------------------------------------------------------------
-*/
// Main Program

void main()
{
P0=0x00; //Port0 as output port
while(1) //Loop forever
{
led = 1; //Set the led to high
DelayMs(500); //Delay for 500ms
led = 0; //Set the led to low
DelayMs(500); //Delay for 500ms
}
}

/***************************
// Delay for 1 msec
****************************/

void DelayMs(unsigned int k)

{
unsigned int i,ms;
for(ms=0;ms<=k;ms++)
{
for(i=0;i<=114;i++);
}
}

Execution:

Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 16 -
/*---------------------------------------------------------------------
Example 2 : Program to Blink LED at Port P0
Description : Connect a LED at a port pins and make it
flash at predefined intervals.
Company : PANTECH SOLUTIONS PVT LTD
----------------------------------------------------------------------*/
Flow Chart

- 17 -
Code:

#include<reg51.h> //Define 8051 Registers

#define led P0 //Define P0 for Led
void DelayMs(unsigned int a); //Delay function

/*---------------------------------------------------------------------
// Main Program
----------------------------------------------------------------------*/

void main()
{
P0=0x00; //Port0 as output port
while(1) //Loop forever
{
led = 0xff; //Set the all led to high
DelayMs(500); //Delay for 500ms
led = 0x00; //Set the all led to low
DelayMs(500); //Delay for 500ms
}
}

/***************************
// Delay for 1 msec
****************************/

void DelayMs(unsigned int k)

{
unsigned int i,ms;
for(ms=0;ms<=k;ms++)
{
for(i=0;i<=114;i++);
}
}

Execution:

Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 18 -
2. Write a Program for serial communication.

Aim

To write a Program for serial communication

Program

1) RS-232 communication enables point in data acquisition applications, for the

transfer of data between the microcontroller and a PC.

2) The voltage levels of a microcontroller and PC are not directly compatible with
those of RS-232, a level transition buffer such as MAX232 be used.

- 19 -
/*-----------------------------------------------------------------------*/
/* Example 1 : Program to send data serially through serial port */
/* */
/* Company : PANTECH SOLUTIONS */
/* */
/* Description: Output can be viewed through system's hyper terminal */
/* window by setting the baud rate to 9600 */
/*-----------------------------------------------------------------------*/

Flow Chart

- 20 -
Code:

#include <REG51.H> /*SFR register declarations */

#include <stdio.h>
void serial_init(void);

//-------------------------------------------------
//Setup the serial port for 9600 baud at 11.0592MHz.
//-------------------------------------------------
void serial_init(void)
{
SCON = 0x50; /* SCON: mode 1, 8-bit UART, enable rcvr */
TMOD |= 0x20; /* TMOD: timer 1, mode 2, 8-bit reload */
TH1 = 0xFD; /* TH1: reload value for 9600 baud,11.0592MHz*/
TR1 = 1; /* TR1: timer 1 run */
TI = 1; /* TI: set TI to send first char of UART */
}

//--------------------------
//Main Program Starts Here
//--------------------------
void main(void)
{
serial_init();
while (1){
printf ("Hello! World\n"); /* Print "Hello World" */
}
}

Execution:
Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

Output:

- 21 -
/*----------------------------------------------------------------------
Example 2 : Program for serial receive data echo using interrupt
Company : PANTECH SOLUTIONS
Description: The program is designed so as to echo the characters typed
through the HyperTerminal window
-----------------------------------------------------------------------*/

Flow Chart

- 22 -
Code:

#include <reg51.h> //include 8051 header file

#include <stdio.h>
void delay(void);
void serial_init(void);
int y;
/************************** Receive Interrupt Function
******************/
void serial_int() interrupt 4 // serial interrupt
{
unsigned char y;
if(RI==1){
y=SBUF; // read SBUF
SBUF=y; //send new value to SBUF
delay();
} RI=0; // clear RI flag
}
/****************************Initialize serial Function****************/
void serial_init(void)
{
TMOD=0x20; //Timer1 8bit autoreload mode
SCON=0x50; // 8bit UART mode
ES=1; //Enable Serial Port Interrupt
EA=1; //Enable All Interrupt
TH1=0xFD; //set Baud Rate 9600 for 11.09MHz
//TH1=(((F-sc/12)/32)/Baudratval)
TR1=1; // Start timer 1
TI=1;
}
/***************************Delay
Function*******************************/
void delay(void)
{
int i;
for(i=0;i<=10000;i++);
}
/************************** Main Function
********************************/
void main()
{
serial_init();
while(1); // loop infinitely waiting only for serial interrupts
}

Execution:

Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 23 -
3. Write a Program for encryption / decryption.

Aim
Writing a program for encryption/decryption

Program

Cryptography(or cryptology; derived from Greek κρύπτω krýpto "hidden" and the
verb γράφω gráfo "to write" or λέγειν legein "to speak") is the practice and study of
hiding information. In modern times, cryptography is considered to be a branch of
both mathematics and computer science, and is affiliated closely with information
theory, computer security, and engineering. Cryptography is used in applications
present in technologically advanced societies; examples include the security of ATM
cards, computer passwords, and electronic commerce, which all depend on
cryptography.

Until modern times, cryptography referred almost exclusively to encryption, the

process of converting ordinary information (plaintext) into unintelligible gibberish
(i.e., ciphertext). Decryption is the reverse, moving from unintelligible ciphertext to
plaintext. A cipher
encryption and the reversing decryption. The detailed operation of a cipher is
controlled
both by the algorithm and, in each instance, by a (ideally, known only to the
communicants) for a specific message exchange context. Keys are important, as
ciphers without variable keys are trivially breakable and therefore less than useful for
most purposes. Historically, ciphers were often used directly for encryption or
decryption, without additional procedures such as authentication or integrity checks.

- 24 -
/*----------------------------------------------------------------------
Example : Encryption & Decryption
Description : Get data from serial port, decrypted data displayed in
serial window.
Company : PANTECH SOLUTIONS PVT LTD
------------------------------------------------------------------------*/

Flow Chart

- 25 -
Code:

#include<reg51.h> //include the 8051 registers

#include<stdio.h> //include the std i/o header files

/******************* Variable Declaration ****************************/

unsigned int i,n,p,z=37;
unsigned char x[10],y[10];
unsigned char msg1[8],enter[]="\nEnter the No of Character : ";
code unsigned char menu[]="\n"
" Encryption Decryption Program "
"\n----------------------------------- "
"\n Press '1': Get Data from keyboard "
"\n Press '2': Display Decrypted Text ";

/******************* Function Declaration ****************************/

void serial();
void encrypt();
void decrypt();
void delay(unsigned int );

/********************* Main Function ****************************/

void main()
{
EA=1; //Enable the Global interrpt
ES=1; //Enable serial Interrupt
serial(); //call serial routine
delay(100);
while(1); //loop forever
}

/******************* Serial Function ****************************/

void serial()
{
SCON = 0x50; /* SCON: mode 1, 8-bit UART, enable rcvr */
TMOD |= 0x20; /* TMOD: timer 1, mode 2, 8-bit reload */
TH1 = 0xFD; /* TH1: reload value for 9600 baud,11.0592MHz*/
TR1 = 1; /* TR1: timer 1 run */
TI = 1; /* TI: set TI to send first char of UART */
i = 0;
while(menu[i] != '\0')
{
SBUF = menu[i];
delay(20);
i++;
z--;
if(z == 0)
{
z =37; //check end of line
SBUF = 0x0d; //carriage return

- 26 -
delay(50);
}
}
}
/******************** Delay Subroutine ****************************/
void delay(unsigned int k)
{
unsigned int a;
for(a=0;a<k;a++);
}
/************************** Encryption ****************************/
void encrypt()
{
i = 0;
SBUF = 0x0d; //CR
delay(100);
while(enter[i] != '\0')
{
SBUF = enter[i];
delay(100);
i++;
}
while(RI == 0);
n = SBUF;
RI = 0;
SBUF = n;
delay(100);
SBUF = '\n';
delay(100);
SBUF = '\n';
delay(100);
n = n-0x30;
for(i=0;i<n;i++)
{
while(RI==0);
msg1[i]=SBUF;
delay(100);
printf("\n");
SBUF=msg1[i];
delay(100);
p=(n-i)-1;
printf(":still %d character remaining:\n",p);
printf("\n");
RI=0;
}
printf("Encrypted Text: ");
for(i=0;msg1[i]!='\0';i++) //Encryption progress
{
x[i]=(msg1[i]+10);
delay(100);
printf("%c",x[i]);

- 27 -
}
delay(100);
printf("\n");
EA=1; //enable the serial interrupt
ES=1;
}
/************************** Decryption ****************************/
void decrypt()
{
printf("\nDecrypted Text: ");
for(i=0;i<n;i++) //Decryption progress
{
y[i]=(x[i]-10);
delay(100);
printf("%c",y[i]);
}
printf("\n");
}
/************************** Serial Interrupt Routine
*********************/
void serin() interrupt 4
{
unsigned char z;
if(RI==1)
{
z=SBUF;
RI=0;
switch(z)
{
case 0x31: //Adcii '1'
encrypt(); //encrypt function
break;
case 0x32: //Ascii '2'
decrypt(); //decrypt function
break;
}
}
}

Execution:
Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 28 -
Output Simulation:

- 29 -
4. Develop necessary interfacing circuit to read data from a sensor and
process using the 801 and 8051 boards. The data to be displayed on a PC
monitor.

Aim

To Develop necessary interfacing circuit to read data from a sensor and

process using the 801 and 8051 boards. The data to be displayed on a PC monitor.

Program

Analog to Digital Converter unit (ADC 0809)

ADC 0809 is an 8-channel 10

Digital form. In ADC section a jumper is provided to select either external analog
input from signal conditioning as input source or can select internal 5V generator,
which is variable from 0-5V. Th
the any of the port by using the Bus/connector. Reference voltage of 2.5V is given at
the reference input so that the analog input span is 5V. In a sample program
provided with the module the digital ou
Microcontroller, can be view on the hyper terminal of the PC
Features of ADC0809:
 Resolution: 8 Bits.
 Operates ratio metrically or with 5VDC, 2.5VDC, or analog span adjusted
 voltage reference.
 Differential analog voltage inputs
 Works with 2.5V voltage reference.
 On-chip clock generator.
 0V to 5V analog input voltage range with single 5V supply.
 No zero adjusts required.

- 30 -
/*----------------------------------------------------------------------*/
/* Example : Program to read Temperature value from ADC */
/*----------------------------------------------------------------------*/
/* Company :PANTECH SOLUTIONS */
/*----------------------------------------------------------------------*/
/* Note :The ADC data lines are interfaced in the Port1 and the
Obtained value in Port1 is converted to decimal value
/*----------------------------------------------------------------------*/

Flow Chart

- 31 -
#include <stdio.h> //Define I/O Functions
#include <reg51.h> //Define 8051 Registers
#include <ctype.h>

//-----------------------------
// ADC Control Lines
//-----------------------------

sbit A0 = P2^7; //Address lines Initialization

sbit A1 = P2^6;
sbit A2 = P2^5;
sbit CS = P2^4; //Chip Select Pin
void serial(); //Serial Port Initialization
void delay1(int);
void delay2(int);
unsigned char READ_ADC(void);
unsigned char ch;
unsigned int i;

//-----------------------------
//Delay Function
//-----------------------------

void delay1(int n)
{
int i;
for(i=0;i<n;i++);
}
void delay2(int n)
{
int i;
for(i=0;i<n;i++)
delay1(1000);
}

//-------------------------------------
//Serial Port Initialization
//-------------------------------------

void serial()
{
SCON=0x50; //Serial Mode-1, REN enable
TMOD=0x20; //Timer1, Mode2, 8-bit (Auto Relod mde)
TH1=0xfd; //9600 Baud rate at 11.0592MHz
TR1=1; //Timer 1 ON
TI=1; //Transmit Interrupt Enable
}

- 32 -
//--------------------------
//ADC Function
//--------------------------

unsigned char READ_ADC()

{
unsigned char ADC_DATA;
CS = 0; delay2(1); //Triggering ADC by chip Slt Pin
CS = 1; delay2(1);
CS = 0; delay2(1);
CS = 1; delay2(1);
ADC_DATA = P1; //Get the value from Port1
return(ADC_DATA);
}

//--------------------------
// Main Program
//--------------------------

void main(void)
{
P1=0xFF;
serial(); //Serial port Initialization
A0 = 0; // channel '0' LM35 Sensor
A1 = 0;
A2 = 0;
printf("ADC Demo - Channel '0' LM35(Temp Sensor) \n");
printf("--------------------------------------------\n");
while(1)
{
ch = READ_ADC(); //Get the value from Channel-0
printf("\rCH0(Temperature) = %2bd’C",toascii(ch*2));
delay2(2);
}
}

Execution:

Note: After Loading corresponding Examples Hex file located in “OUT”

Folder to the microcontroller kit, press “RST” Button, user program now
executes.

- 33 -
5. Sort RTOs (mCOS) on to 89CS1 board and Verify.

Aim

To Sort RTOs (mCOS) on to 89CS1 board and Verify.

Program

- 34 -
/
*********************************************************************
**/
/* Round Robin Scheduling Multitasking */
/* Note: LED’s Blinked in different Delay intervals */
/
*********************************************************************
**/

#include <rtx51tny.h> // RTX-51 tiny functions & defines

#include <reg52.h> /* 8051 Register */
sbit LED0 = P0^0; /* LED0 for task1 */
sbit LED1 = P0^2; /* LED0 for task2 */
sbit LED2 = P0^4; /* LED0 for task3 */

/
*********************************************************************
***/
/* Task 0 'job0': RTX-51 tiny starts execution with task 0 */
/
*********************************************************************
***/

job0 () _task_ 0
{
P1 = 0x00; //P1 make it output port
os_create_task (1); /* start task 1 */
os_create_task (2); /* start task 2 */
os_create_task (3); /* start task 3 */
while (1) { /* endless loop */
os_wait (K_TMO, 5, 0); /* wait for timeout: 5 ticks */
}
}

/
*********************************************************************
*/
Task 1 'job1': RTX-51 tiny starts this task with os_create_task (1)
/
*********************************************************************
*/

job1 () _task_ 1
{
while (1) { /* endless loop */
LED0 = 1;
os_wait (K_TMO, 30, 0);
LED0 = 0;
os_wait (K_TMO, 30, 0); /* wait for timeout: 10 ticks */
}

- 35 -
}

- 36 -
/
*********************************************************************
*/
/* Task 2 'job2': RTX-51 tiny starts this task with os_create_task (2) */
/
*********************************************************************
*/

job2 () _task_ 2
{
while (1) { /* endless loop */
LED1 = 1;
os_wait (K_TMO, 50, 0);
LED1 = 0;
os_wait (K_TMO, 50, 0); /* wait for timeout: 50 ticks */
}
}

/
*********************************************************************
***/
/* Task 3 'job3': RTX-51 tiny starts this task with os_create_task (3) */
/
*********************************************************************
****/

job3 () _task_ 3
{
while (1) { /* endless loop */
LED2 = 1;
os_wait (K_TMO, 80, 0);
LED2 = 0;
os_wait (K_TMO, 80, 0); /* wait for timeout: 80 ticks */
}
}

Execution:
Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 37 -
Example 2: Cooperative Scheduling Multitasking

- 38 -
/
*********************************************************************
*/
/* Cooperative Scheduling Multitasking */
/* Note: LED Blink, UART, LCD (runs simultaneously) */
/
*********************************************************************
*/

#include <rtx51tny.h> // RTX-51 tiny functions & defines

#include <stdio.h>
#include <reg52.h> //8051 Register
#define LCD_DATA P1 //Define LCD_DATA Lines to Port(Port1)
#define LED P0 // Define LED for PORT 0

/*****************Define LCD control pins*************************/

sbit RS = P3^5; //Register Select

sbit RW = P3^6; //LCD Read/Write
sbit lcd_e = P3^7; //LCD Enable
code unsigned char msg[] = (" 8051 MCOS RTOS "); //Display the message
code unsigned char msg1[] = (" MULTITASKING ");
void lcd_cmd(unsigned char);
void lcd_display(unsigned char);

/*******************************************************************/
/* Task 0 : RTX-51 tiny Initializ task */
/*******************************************************************/

void init(void)_task_ 0
{
os_create_task (1); // start task 1 INIT_UART
os_create_task (2); // start task 2 SEND_UART
os_create_task (3); // start task 2 LED Blink
os_create_task (4); // start task 2 LCD Display
while (1)
{ // endless loop
os_wait (K_TMO, 5, 0); // wait for timeout: 5 ticks
}
}

- 39 -
/*******************************************************************/
/* Task 1 : RTX-51 tiny starts initialize serial port with task 0 */
/*******************************************************************/

void uart (void) _task_ 1

{
SCON = 0x50; // SCON: mode 1, 8-bit UART, enable rcvr
TMOD |= 0x20; // TMOD: timer 1, mode 2, 8-bit reload
TH1 = 0xFD; // TH1: reload value for 9600/11.0592MHz
TR1 = 1; // TR1: timer 1 run
TI = 1; // TI: set TI to send first char of UART
}

/
*********************************************************************
/
/* Task 2 : RTX-51 tiny starts send UART data with task 0 */
/********************************************************************/
void uart_send(void) _task_ 2
{
while (1)
{
os_wait (K_TMO, 10, 0);
SBUF = 'A';
}
}

/********************************************************************/
/* Task 3 : RTX-51 tiny starts LED Blink with task 0 */
/********************************************************************/

void led(void) _task_ 3

{
while (1) { // endless loop
LED = 0x55;
os_wait (K_TMO, 30, 0);
LED = 0xAA;
os_wait (K_TMO, 30, 0);
}
}

- 40 -
/
*********************************************************************
*/
/* Task 4 : RTX-51 tiny starts LCD Initializaion with task 0 */
/
*********************************************************************
*/

void lcd(void) _task_ 4

{
while (1) { // endless loop
unsigned char i;
lcd_cmd(0x38); //2x16 Character 5x7 dot
os_wait (K_TMO, 2, 0);
lcd_cmd(0x0c); //Display On, cursor off
os_wait (K_TMO, 2, 0);
lcd_cmd(0x06); //Shift Cursor to right
os_wait (K_TMO, 2, 0);
lcd_cmd(0x01); //Clear display screen
os_wait (K_TMO, 2, 0);

//-------------------------------------------
// First Line Message Display
//-------------------------------------------

lcd_cmd(0x80); //First Line Initialization

os_wait (K_TMO, 2, 0);
i=0;
while(msg[i]!='\0')
{
lcd_display(msg[i]);
i++;
}
os_wait (K_TMO, 4, 0);

//-------------------------------------------
// Second Line Message Display
//-------------------------------------------

lcd_cmd(0xc0); //Second Line Initialization

os_wait (K_TMO, 2, 0);
i=0;
while(msg1[i]!='\0')
{
lcd_display(msg1[i]);
i++;
}
os_wait (K_TMO, 4, 0);
}
}

- 41 -
//----------------------------------
// LCD command Function
//----------------------------------

void lcd_cmd(unsigned char cmnd)

{
LCD_DATA = cmnd;
RS = 0; RW = 0;
lcd_e = 1;
os_wait (K_TMO, 2, 0);
lcd_e = 0;
}

//----------------------------------
// LCD Data Function
//----------------------------------

void lcd_display(unsigned char dat)

{
LCD_DATA = dat;
RS = 1; RW = 0;
lcd_e = 1;
os_wait (K_TMO, 2, 0);
lcd_e = 0;
}

Execution:

Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 42 -
6. Simulate on elevator movement using RTO’s on 89CSI board.

- 43 -
/
*********************************************************************
***/
/* Task_Init.h:
/* Project specific header for the Elevator example
/
*********************************************************************
***/

#define LCD_DATA P1 //Define LCD_DATA Lines to Port(Port1)

#define LED P0 // Define LED for PORT 0

#define INIT 0 //Task0 for Initialize all task

#define UART 1 //Task1 for UART
#define UART_SEND 2 //Task2 for UART_send data
#define LCD_INIT 3 //Task3 for LCD Initialize
#define KEY_OUT 4 //Task4 for Key out for outside elevator
#define KEY_IN 5 //Task5 for Key in for inside elevator

code unsigned char msg0[] = ("ELEVATOR SIMULATION "); //serial communi

msg
code unsigned char msg[] = (" RTX-51 BASED “); //Display the message
code unsigned char msg1[] = (" ELEVATOR SIMUL ");
code unsigned char msg2[] = ("OPEN "); //lcd/uart msg
code unsigned char msg3[] = ("CLOSE");

- 44 -
/
*********************************************************************
***/
/* Elevator Simulation by using RTOS(Multitasking) */
/
*********************************************************************
***/

#include <rtx51tny.h> // RTX-51 tiny functions & defines

#include <reg51.h> //8051 Register
#include "task_init.h" // project specific header file

/***********************Define LCD control

pins*************************/

sbit RS = P3^5; //Register Select

sbit RW = P3^6; //LCD Read/Write
sbit lcd_e = P3^7; //LCD Enable
unsigned char R,C,ch;
unsigned int i=0,j=0;
code unsigned char Key[4][2] = { '0','5', //Matrix Keypad Character
'1','6', //Initialization
'2','7', //Initialization
'3','8', //Initialization
};

void lcd_cmd(unsigned char);

void lcd_display(unsigned char);
void open(void);
void close(void);
void DelayMs(int);
void upscroll(int n);
void downscroll(int n);

/
*********************************************************************
*/
/* Task 0 : RTX-51 tiny Initializ task */
/
*********************************************************************
*/

void init(void)_task_ INIT

{
P0 = 0x00;
os_create_task (UART); // start task 4 INIT_UART
os_create_task (UART_SEND); // start task 5 UART_SEND
os_create_task (LCD_INIT); // start task 1 INIT_LCD
os_create_task (KEY_OUT); // start task 3 Floor Status
os_create_task (KEY_IN); // start task 3 Floor Status
while (1)

- 45 -
{ // endless loop
os_wait (K_TMO, 5, 0); // wait for timeout: 5 ticks
}
}

- 46 -
/
*********************************************************************
*/
/* Task 1 : RTX-51 tiny starts initialize serial port with task 0 */
/
*********************************************************************
*/

void uart (void) _task_ UART

{
SCON = 0x50; // SCON: mode 1, 8-bit UART, enable rcvr
TMOD |= 0x20; // TMOD: timer 1, mode 2, 8-bit reload
TH1 = 0xFD; // TH1: reload value for 9600 @ 11.0592MHz
TR1 = 1; // TR1: timer 1 run
TI = 1; // TI: set TI to send first char of UART
}

/
*********************************************************************
/
/* Task 2 : RTX-51 tiny starts send UART data with task 0 */
/
*********************************************************************
/

void uart_send(void) _task_ UART_SEND

{
while(msg0[j]!='\0')
{
SBUF=msg0[j];
j++;
os_wait (K_TMO, 2, 0);
} os_wait (K_TMO, 2, 0);
}

/
*********************************************************************
**/
/* Task 3 : RTX-51 tiny starts LCD Initializaion with task 0 */
/
*********************************************************************
**/

void lcd(void) _task_ LCD_INIT

{
while (1) { // endless loop
unsigned char 1;
lcd_cmd(0x38); //2x16 Character 5x7 dot
os_wait (K_TMO, 2, 0);
lcd_cmd(0x0c); //Display On, cursor off
os_wait (K_TMO, 2, 0);

- 47 -
lcd_cmd(0x06); //Shift Cursor to right
os_wait (K_TMO, 2, 0);
lcd_cmd(0x01); //Clear display screen
os_wait (K_TMO, 2, 0);

- 48 -
//-------------------------------------------
// First Line Message Display
//-------------------------------------------

lcd_cmd(0x80); //First Line Initialization

os_wait (K_TMO, 2, 0);
i=0;
while(msg[i]!='\0')
{
lcd_display(msg[i]);
i++;
} os_wait (K_TMO, 4, 0);

//-------------------------------------------
// Second Line Message Display
//-------------------------------------------

lcd_cmd(0xc0); //Second Line Initialization

os_wait (K_TMO, 2, 0);
i=0;
while(msg1[i]!='\0')
{
lcd_display(msg1[i]);
i++;
}

os_wait (K_TMO, 4, 0);

os_delete_task (LCD_INIT);
}
}

/***************************Elevator Open
******************************/

void open(void)
{
lcd_cmd(0xca); //Second Line Initialization
os_wait (K_TMO, 2, 0);
i=0;
while(msg2[i]!='\0')
{
lcd_display(msg2[i]);
os_wait (K_TMO, 1, 0);
SBUF = msg2[i];
i++;
}
os_wait (K_TMO, 4, 0);
}

- 49 -
/***************************Elevator Close
******************************/

void close(void)
{
lcd_cmd(0xca); //Second Line Initialization
os_wait (K_TMO, 2, 0);
i=0;
while(msg3[i]!='\0')
{
lcd_display(msg3[i]);
os_wait (K_TMO, 1, 0);
SBUF = msg3[i];
i++;
}
os_wait (K_TMO, 4, 0);
}

/***************************LED UP scroll
******************************/

void upscroll(int n)
{
int i,j=0;
for(i=0;i<n;i++)
{
for(j=0x10;j<=0x80;j<<=1) //shift led one position
{
P0=j; //Initialize Port1
os_wait (K_TMO, 20, 0);
}
}
}

/***************************LED Downscroll
*****************************/
void downscroll(int n)
{
int i,j=0;
for(i=0;i<n;i++)
{
for(j=0x80;j>=0x10;j>>=1) //shift led one position
{
P0=j; //Initialize Port1
os_wait (K_TMO, 20, 0);
}
}
}

- 50 -
/***************************LCD Command
*****************************/

void lcd_cmd(unsigned char cmnd)

{
LCD_DATA = cmnd;
RS = 0; RW = 0;
lcd_e = 1;
os_wait (K_TMO, 2, 0);
lcd_e = 0;
}

/***************************LCD Display
******************************/

void lcd_display(unsigned char dat)

{
LCD_DATA = dat;
RS = 1; RW = 0;
lcd_e = 1;
os_wait (K_TMO, 2, 0);
lcd_e = 0;
}

/
*********************************************************************
*/
/* Task 4 : RTX-51 tiny starts Elevator outside key with task 0 */
/
*********************************************************************
*/

void Key_Scan_out(void) _task_ KEY_OUT

{
while(1){
unsigned int i = 0;
//Scanning for Row Value
P2 = 0x0F; //Initialize Port2 to 0Fh
while(P2 == 0x0F);
if(P2 == 0x0E) //Checking from Row 0 to 3
R = 0;
else if(P2 == 0x0D)
R = 1;
else if(P2 == 0x0B)
R = 2;
else if(P2 == 0x07)
R = 3;
//Scanning for Column Value
P2 = 0xF0;
//Initialize Port2 to F0h
while(P2 == 0xF0);

- 51 -
if(P2 == 0xE0) //Checking from Column 0 to 3
C = 0;
else if(P2 == 0xD0)
C = 1;
else if(P2 == 0xB0)
C = 2;
else if(P2 == 0x70)
C = 3;
os_wait (K_TMO, 10, 0);
//Floor Status
ch = Key[R][C];
if(ch=='0')
{
downscroll(1);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 2, 0);
os_create_task (KEY_IN); //create keyscan inside
P0 =0x08;
}
if(ch=='1')
{
downscroll(2);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 1, 0);
os_create_task (KEY_IN); //create keyscan inside
P0 = 0x04;
}
if(ch=='2')
{
downscroll(3);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 1, 0);
os_create_task (KEY_IN); //create keyscan inside
P0 = 0x02;
}
if(ch=='3')
{
downscroll(4);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 1, 0);
os_create_task (KEY_IN); //create keyscan inside
P0 = 0x01;
}
}
}

- 52 -
/
*********************************************************************
*/
/* Task 5 : RTX-51 tiny starts Elevator inside key with task 0 */
/
*********************************************************************
*/

void Key_Scan_in(void) _task_ KEY_IN

{
while(1){
unsigned int i = 0;
//Scanning for Row Value
P2 = 0x0F; //Initialize Port2 to 0Fh
while(P2 == 0x0F);
if(P2 == 0x0E) //Checking from Row 0 to 3
R = 0;
else if(P2 == 0x0D)
R = 1;
else if(P2 == 0x0B)
R = 2;
else if(P2 == 0x07)
R = 3;
//Scanning for Column Value
P2 = 0xF0; //Initialize Port2 to F0h
while(P2 == 0xF0);
if(P2 == 0xE0) //Checking from Column 0 to 3
C = 0;
else if(P2 == 0xD0)
C = 1;
else if(P2 == 0xB0)
C = 2;
else if(P2 == 0x70)
C = 3;
os_wait (K_TMO, 10, 0);
//Elevator Inside
ch = Key[R][C];
if(ch=='5')
{
upscroll(1);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 2, 0);
P0 = 0x08;
os_create_task (KEY_OUT); //create keyscan inside
}
if(ch=='6')
{
upscroll(2);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 2, 0);
P0 = 0x04;

- 53 -
os_create_task (KEY_OUT); //create keyscan inside
}
if(ch=='7')
{
upscroll(3);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 2, 0);
P0 = 0x02;
os_create_task (KEY_OUT); //create keyscan inside
}
if(ch=='8')
{
upscroll(4);
open(); os_wait (K_TMO, 200, 0);
close(); os_wait (K_TMO, 2, 0);
P0 = 0x01;
os_create_task (KEY_OUT); //create keyscan inside
}
}
}

Execution:
Note: After Loading corresponding Examples Hex file located in “OUT” Folder to
the microcontroller kit, press “RST” Button, user program now executes.

- 54 -
TEXT BOOKS:

1) Computers and Components, Wayne Wolf, Elseveir.

2) The 8051 Microcontroller, Third Edition, Kenneth J. Ayala, Thmson .

REFERENCES:

1) Embedding system building blocks, Labrosse, via CMP publishers.

2) Embedded Systems, Raj Kamal, TMH.
3) Micro Controllers, Ajay V Deshmukhi, TMH.
4) Embedded System Design, Frank Vahid, Tony Givargis, John Wiley.
5) Microcontrollers, Raj Kamal, Pearson Edition.
6) An Embedded Software Primer, David E. Simon, Pearson Edition.
7) ‘Embedded/Real-Time Systems’, KVKKF Prasad, Dreamtech, Press.

- 55 -