Complete Embedded Report

8/3/2019 Complete Embedded Report

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RANSLAM INSTITUTE OF TECHNOLOGY & MANAGEMENT

(MAWANA ROAD,MEERUT)

TRAINING REPORT

ON

EMBEDDED SYSTEM

B.TECH(2011)(DEPARTMENT OF ELECTRONICS AND COMMUNICATION)



PERFACE

First of all it is our proud to express our heartfelt gratitude to

supreme power . The almighty lord, the ultimate creator of thewhole world, who always guards us on the right path of life.

Without his grace, this task of work would have never been to

a successful end.

We are wishing to express our heartfelt gratitude to my guide,who has been helpful to me in completing this training. We

intent our forthright thanks to staff of the cad arena who

provide us the final tips that helped us to improve our

performance.Finally, we are indwelled to my parents for their love and

moral supports whose encouragement pushed us to achieve

this goal, without which we should have been able to fight out

all odds during my training.



ACKNOWLEDGEMENTS

First and foremost, I would like to thank my respectedparents, who always encouraged me and taught me to

think and workout innovatively what so ever be the field

of life. My sincere thanks goes to Mr. Taz (Cad Arena,

Dehradun) for his prodigious guidance, persuasion, andpainstaking attitude, reformative and prudential

suggestion throughout my summer training schedule.

Last but not the least, my sincere thanks to all the staff

members and friends for instilling in me a sense of self-

confidence.



CONTENTS1. Introduction to Embedded System

1.1-Introduction

1.2-What is an Embedded System

1.3-Three criteria choosing Microcontroller

2. Introduction to 8051 microcontroller2.1-Block diagram of 8051 Microcontroller

2.2-Pin description of 8051 Microcontroller

2.3-Pins of I/O Port

2.4-Hardware structure of I/O Pin

2.5-Other Pins

2.6-Port 3 Alternate Function

3. 8051 Timers/Counter3.1-Timer/Counter Programming

3.2-Timer

3.3-Timer Modes3.4-Delay Length Factors

3.5-Timer Delay Calculation in sec

3.6-Findings THx and TLx when time is known

3.7-Counter

4. 8051 Interrupts4.1-Interrupt Programming



5. Serial Communication in 80515.1-Basics of Serial Communication

5.2-Packaging data (Start and Stop bits)

5.3-Serial Control (SCON) Ragister

5.4-Modes of Operation

6. 8051 Registers6.1-TMOD Register

6.2-TCON Register

6.3-Interrupt Enable Register

7. Programs Examples Using ³C´

7.1-Write a program to toggle all pins of P1 continously

7.2-Write a program to toggle bit D0 of Port P1 (P1.0) 50,000 times

7.3-Write a program to get a byte data from P0,if it is less than 100,send it to

Port1;otherwise send it to port27.4-Write a program to monitor a bit P1.5,if it is high send 55H to P0;otherwise send

AAH to P2

8. Application Of Embedded System

9. Summary



Introduction toEmbedded Systems



INTRODUCTION

The embedded systems is wide and

varied, and it is difficult to exact

definitions or descriptions.

Chapter 1 introduces a useful model that

can be applied to any embedded system.

Chapter 2 introduces and defines thecommon standard com ponents when

building an embedded system.



What Is an Embedded System?

An embedded system is an applied computer system

"embedded system", it constantly evolves with

advances in technology and dramatic decreasesin the cost of implementing various hardwareand software components.

In recent years, the field has outgrown many of its traditional descriptions.

Following are a few of the more commondescriptions of an embedded system:



1. meeting the computing needs of the task efficiently and cost

effectively

speed, the amount of ROM and RAM, the number of I/O

ports and timers, size, packaging, power consumption easy to upgrade

cost per unit

2. availability of software development tools

assemblers, debuggers, C compilers, emulator, simulator,technical support

3. wide availability and reliable sources of the microcontrollers.

Three criteria in Choosing a Microcontroller



Introduction to 8051

Microcontroller



Block DiagramB

lock Diagram

CPU

On-chip

RAM

On-chip ROM

for program

code

4 I/O Ports

Timer 0

Serial

PortOSC

Interrupt

Control

External interrupts

Timer 1

Timer/Counter

Bus Control

TxD RxDP0 P1 P2 P3

Address/Data



PinPin DescriptionDescription of of thethe 80518051

1

2

3

4

5

6

78

9

10

11

12

13

14

15

16

17

18

19

20

40

39

38

37

36

35

3433

32

31

30

29

28

27

26

25

24

23

22

21

P1.0

P1.1

P1.2

P1.3

P1.4

P1.5

P1.6P1.7

RST

(RXD)P3.0

(TXD)P3.1

(T0)P3.4(T1)P3.5

XTAL2

XTAL1

GND

(INT0)P3.2

(INT1)P3.3

(RD)P3.7

(WR)P3.6

Vcc

P0.0(AD0)

P0.1(AD1)

P0.2(AD2)

P0.3(AD3)

P0.4(AD4)

P0.5(AD5)P0.6(AD6)

P0.7(AD7)

EA/VPP

ALE/PROG

PSEN

P2.7(A15)

P2.6(A14)

P2.5(A13)

P2.4(A12)

P2.3(A11)

P2.2(A10)

P2.1(A9)

P2.0(A8)

8051

(8031)



Pins of 8051 (1/4)

Vcc pin 40

±Vcc provides supply voltage to the chip.

± The voltage source is +5V. GND pin 20ground

XTAL1 and XTAL2 pins 19,18



Pins of 80512/4

RST pin 9reset

± It is an input pin and is active highnormally

low.

The high pulse must be high at least 2machine cycles.

± It is a power-on reset.

Upon applying a high pulse to RST, themicrocontroller will reset and all values in

registers will be lost.

Reset values of some 8051 registers



Pins of 80513/4

/EA pin 31external access

± There is no on-chip ROM in 8031 and 8032 .

± The /EA pin is connected to GND to indicate the

code is stored externally.

± /PSEN

ALE are used for external ROM.

± For 8051, /EA pin is connected toVcc.

± ³/´ means active low.

/PSEN pin 29 program store enable

± This is an output pin and is connected to the OE pinof the ROM.



Pins of 80514/4

ALE pin 30address latch enable ± It is an output pin and is active high.

± 8051 port 0 provides both address and data.

± The ALE pin is used for de-multiplexing theaddress and data by connecting to the G pin of the 74LS373 latch.

I/O port pins

± The four ports P0, P1, P2, and P3. ± Each port uses 8 pins.

± All I/O pins are bi-directional..



Pins of I/O Port

The 8051 has four I/O ports ± Port 0 pins 32-39P0P0.0P0.7

± Port 1 pins 1-8 P1P1.0P1.7

± Port 2 pins 21-28P2P2.0P2.7

± Port 3 pins 10-17P3P3.0P3.7

± Each port has 8 pins. Named P0.X X=0,1,...,7, P1.X, P2.X, P3.X

ExP0.0 is the bit 0LSBof P0

ExP0.7 is the bit 7MSBof P0

These 8 bits form a byte.

Each port can be used as input or output (bi-direction).



Hardware Structure of I/O Pin

Each pin of I/O ports

± Internal CPU buscommunicate with CPU

± A D latch store the value of this pin

D latch is controlled by³Write to latch´

± Write to latch1write data into the D latch

± 2 Tri-state buffer

TB1: controlled by ³Read pin´

± Read pin

1

really read the data present at the pin TB2: controlled by ³Read latch´

± Read latch1read value from internal latch

± A transistor M1 gate

Gate=

0: open Gate=1: close



Other Pins P1, P2, and P3 have internal pull-up resisters.

± P1, P2, and P3 are not open drain.

P0 has no internal pull-up resistors and does notconnects to Vcc inside the 8051.

± P0 is open drain.

± Compare the figures of P1.X and P0.X.

However, for a programmer, it is the same to programP0, P1, P2 and P3.

All the ports upon RESET are configured as output.



Port 3 Alternate Functions

1717RDRDP3.7P3.7

1616WR WR P3.6P3.6

1515T1T1P3.5P3.5

1414T0T0P3.4P3.4

1313INT1INT1P3.3P3.3

1212INT0INT0PP33..22

1111TxDTxDP3.1P3.1

1010RxDRxDP3.0P3.0

PinPinFunctionFunctionP3 BitP3 Bit



8051

timer/counter



Timers /Counters Programming

The 8051 has 2 timers/counters:

timer/counter 0

timer/counter 1

They can be used as

1. The timer is used as a time delay generator .

± The clock source is the internal crystal frequency of the

8051.

2.

An event counter .

± Ex ternal input from input pin to count the number of

events on registers.

± These clock pulses cold represent the number of people

passing through an entrance, or the number of wheel

rotations, or any other event that can be converted to



Timer

Set the initial value of registers

Start the timer and then the 8051 counts up.

Input from internal system clock (machine cycle)

When the registers equal to 0 and the 8051 setsa bit to denote time out

toLCD

P1

8051

TL0

TH0

P2SetTimer 0



Timer Mode 1

In following, we all use timer 0 as an example.

16-bit timer (TH0 and TL0)

TH0-TL0 is incremented continuously when TR0 is set

to 1. And the 8051 stops to increment TH0-TL0 when

TR0 is cleared.

The timer works with the internal system clock . In

other words, the timer counts up each machine cycle.

When the timer (TH0-TL0) reaches its maximum of

FFFFH, it rolls over to 0000, and TF0 is raised.

Programmer should check TF0 and stop the timer 0.



Delay length factors Timer freq.or Machine cycle frequency=1/12 clock frequency (when timer is used for generating delays)

AT89C51 : 12 clocks per machine cycle

DS89C4x0 : 1 clock per machine cycle Delay length depends upon

Crystal frequency

No.Of clocks per machine cycle

C-compiler



Timer delay calculation in sec.

When the values of Thx and TLx are known :

Suppose hex value is YYXX = TH + TL

Calculation in HEX :

Step1 : [ FFFF-YYXX+1 ] x 1.085uS

Calculation in decimal :

Step1 : Convert YYXX into decimal NNNN.

Step2 : [ 65,536 ± NNNN ] x 1.085 uS



Finding THx and TLx when time is

known :

For 11.0592 MHz XTAL frequency :

Step 1 : Desired time delay / 1.085 uS = n

in decimalStep 2 : 65,536 ± n = M

Step 3 : Convert M into hex value YYXX

Step 4 : THx =YY

Step 5 : Tlx = XX



Counter

Count the number of events

± Show the number of events on registers

± External input from T0 input pin (P3.4) for Counter

0

± External input from T1 input pin (P3.5) for Counter 1

± External input from Tx input pin.

± We use Tx to denote T0 or T1.

T0

toLCD

P3.4

P1

8051

a switch

TL0

TH0



8051

Interrupts



Interrupts Programming

An interrupt is an external or internal event thatinterrupts the microcontroller to inform it that a

device needs its service.

I nterrupts vs. Polling

A single microcontroller can serve several devices.

There are two ways to do that:

± interrupts

± polling. The program which is associated with the interrupt is

called the interrupt service routine (ISR) or interrupt

handler .



Steps in executing an interrupt

Finish current instruction and saves the PC on stack .

Jumps to a fixed location in memory depend on type

of interrupt

Starts to execute the interrupt service routine until

RETI (return from interrupt)

Upon executing the RETI the microcontroller returns

to the place where it was interrupted. Get pop PC

from stack



Interrupt Sources

Original 8051 has 6 sources of interrupts ± Reset

± Timer 0 overflow

± Timer 1 overflow

± External Interrupt 0

± External Interrupt 1

± Serial Port events (buffer full, buffer empty, etc)

Enhanced version has 22 sources ± More timers, programmable counter array, ADC, more

external interrupts, another serial port (UART)



Interrupt Enable (IE) register

All interrupt are disabled after resetWe can enable and disable them bye IE



External interrupt type control By low nibble of Timer control register TCON

I E0 ( I E1 ): External interrupt 0(1) edge flag. ± set by CPU when external interrupt edge ( H-to-L) is detected.

± Does not affected by H-to-L while ISR is executed(no int on int)

± C lear ed by CPU when R ET I executed.

± does not latch low-level triggered interrupt

I T0 ( I T1 ): interrupt 0 (1) type control bit.

± Set/cleared by software

± IT=1 edge trigger

± IT=0 low-level trigger

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

Timer 1 Timer0 for Interrupt

(MSB) (LSB)



Interrupt Priorities

What if two interrupt sources interrupt at the same time?

The interrupt with the highest PR IO R I TY gets

serviced first .

All interrupts have a power on default priority order .

1. External interrupt 0 (INT0)

2. Timer interrupt0 (TF0)

3. External interrupt 1 (INT1)

4. Timer interrupt1 (TF1)

5. Serial communication (RI+TI)

Priority can also be set to³high´ or

³low´ by

I P reg

.



Interrupt Priorities (IP) Register

IP.7: reserved

IP.6: reservedIP.5: timer 2 interrupt priority bit(8052 only)

IP.4: serial port interrupt priority bit

IP.3: timer 1 interrupt priority bit

IP.2: external interrupt 1 priority bit

IP.1: timer 0 interrupt priority bit

IP.0: external interrupt 0 priority bit

--- PX0PT0PX1PT1PSPT2---



Serial

Communication



Basics of serial communication

Parallel : expensive - short distance ± fast ± no modulation

S erial :cheaper± long (two different cities by modem)-slow



Basics of serial communication



Packaging DataStart and stop bits

In asynchronous transmission

When there is no transfer the signal is high

Transmission begins with a start (low) bit

LSB first

Finally 1 stop bit (high)Data transfer rate (baud rate) is stated in b ps



Serial control (SCON) Register:-

SM2 : used for multi processor communication

REN : receive enable (by software enable/disable)

TB8 : transmit bit8

R B8 : receive bit 8

TI : transmit interrupt flag set by HW after send , clear by SW

RI : receive interrupt flag set by HW after received ,clear by SW

SM0 RITIR B8TB8RENSM2SM1

7 6 5 4 3 2 1 0

SM0 SM1 MODE operation transmit rate

0 0 0 shift register fixed (xtal/12)

0 1 1 8 bit UART variable (timer1)

1 0 2 9 bit UART fixed (xtal/32 or xtal/64)

1 1 3 9 bit UART variable (timer1)

SM0 : mode specifier

SM1 : mode specifier



Mode of operation

Mode 0 :

± Serial data enters and exits through Rx D

± T x D outputs the shift clock .

± 8 bits are transmitted/received(LSB first)

± The baud rate is fixed a 1/12 the oscillator frequency.

Application

± Port expansion

8051

TXD

R XD Shift register clk

data



Mode of operation

Mode 1 ± Ten bits are transmitted (through TxD) or received (through RxD)

(A start bit (0), 8 data bits (LSB first), and a stop bit (1) )

± On receive, the stop bit goes into R B8 in SCON

± the baud rate is determined by the Timer 1 overflow rate.

± Timer1 clock is 1/32 machine cycle (MC=1/12 XTAL)

Timer clock can be programmed as 1/16 of machine cycle

Transmission is initiated by any instruction that uses SBUF

as a destination register .



Mode of operation

Mode 2 : ± E leven bits are transmitted (through TxD), received (through

RxD)

A start bit (0)

8 data bits (LSB first)

A programmable 9th data bit and a stop bit (1)

± On transmit, the 9th bit (TB8) can be assigned 0 or 1.

± On receive, the 9the data bit goes into R B8 in SCON.

± the 9th can be parity bit

± The baud rate is programmable to 1/32 or 1/64 the oscillator frequency in Mode 2 by SM O D bit in P C ON register

Mode 3 ± Same as mode 2

± But may have a variable baud rate generated from Timer 1.



The 8051

Ragisters



TMOD Register:

Gate : When set, timer only runs while INT(0,1) is high.

C/T : Counter/Timer select bit.

M1 : Mode bit 1.

M0 : Mode bit 0.



Gate Every timer has a mean of starting and stopping.

± GATE=

0 I nternal control

The start and stop of the timer are controlled by way of software.

Set/clear the TR for start/stop timer .

SETB TR0

CLR TR0

± GATE=1

Ex ternal control

The hardware way of starting and stopping the timer by software andan e x ternal source.

Timer/counter is enabled only while the INT pin is high and the TR

control pin is set (TR).

GATE C/T M1 M0 GATE C/T M1 M0

Timer 1 Timer 0

(MSB) (LSB)



TCON Register:

TF1: Timer 1 overflow flag. TR1: Timer 1 run control bit.

TF0: Timer 0 overflag.

TR0: Timer 0 run control bit.

IE1: External interrupt 1 edge flag. IT1: External interrupt 1 type flag.

IE0: External interrupt 0 edge flag.

IT0: External interrupt 0 type flag.



TCON Register (1/2)

Timer control register: TMOD ± Upper nibble for timer/counter, lower nibble for

interrupts

TR (run control bit)

± TR0 for Timer/counter 0; TR1 for

Timer/counter 1.

± TR is set by programmer to turn timer/counter

on/off . TR =0: off (stop) TR =1: on (start)



(MSB) (LSB)



TCON Register (2/2)

TF (timer flag, control flag) ± TF0 for timer/counter 0; TF1 for timer/counter 1.

± TF is like a carry. Originally, TF=0. When TH-TL roll

over to 0000 from FFFFH, the TF is set to 1.

TF=0 : not reach

TF=1: reach

If we enable interrupt, TF=1 will trigger ISR.



(MSB) (LSB)



Interrupt Enable Register :

EA : Global enable/disable. --- : Undefined.

ET2 :Enable Timer 2 interrupt.

ES :Enable Serial port interrupt.

ET1 :Enable Timer 1 interrupt.

EX1 :Enable External 1 interrupt.

ET0 : Enable Timer 0 interrupt.

EX0 : Enable External 0 interrupt.



Programs Examples

Using ³C´



//Write an 8051 C program to toggle all the bits of P1

continuously.

S olution:

#include <reg51.h>

void main(void){

for (;;) //Toggle P1 forever

{

p1=0x55; p1=0xAA;

}

}



//Write an 8051 C program to toggle bit D0 of the port

P1 (P1.0) 50,000 times.

S olution:

#include <reg51.h>

sbit MYBIT=P1^0;

void main(void)

{

unsigned int z;

for (z=0;z<=50000;z++){

MYBIT=0;

MYBIT=1;

}



//Write an 8051 C program to get a byte of data form P0. If it

is less than 100, send it to P1; otherwise, send it to P2.

S olution:

#include <reg51.h>

void main(void)

{unsigned char mybyte;

P0=0xFF;

while (1)

{mybyte=P0;

if (mybyte<100)

P1=mybyte;

else=



//Write an 8051 C program to monitor bit P1.5. If it is high,

send 55H to P0; otherwise, send AAH to P2.

S olution:

#include <reg51.h>

sbit mybit=P1^5;

void main(void){

mybit=1; //make mybit an input

while (1)

{if (mybit==1)

P0=0x55;

else

P2=0xAA;



Application Of Embedded System



Applicaton Of Embedded System:-

Consumer Electronics

Medical.

Industrial Automation and Control

Networking and Communications

Automotive.

Aerospace and Defense Commercial Office/Home Office

Automation

S



Summary An embedded system is a product that has one or more

computers embedded within it, which exercise primarily a

control function.

The embedded computer is usually a microcontroller: a

microprocessor adapted for embedded control applications.

Microcontrollers are designed according to accepted electronic

and computer principles, and are fundamentally made up of microprocessor core, memory and peripherals.

Microchip offers a wide range of microcontrollers, divided

into a number of different families. Each family has identical

central architecture and instruction set. However, common

features also appear across all their microcontrollers.

The Microchip 12F508 is a good microcontroller to introduce

a range of features of microcontrollers in general and of PIC

microcontrollers in particular .

h i h b d h

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Complete Embedded Report