2011

CHANDAN BERA

4th Year, ECE

ROLL NO-09170003058

Microcontroller Based System Design

CERTIFICATE

TO WHOM IT MAY CONCERN

THIS IS TO CERTIFY THAT, CHANDAN BERA, STUDENT OF

IMPS COLLEGE OF ENGINEERING & TECHNOLOGY IN

ELECTRONICS & COMMUNICATION ENGINEERING COMPLETED

AN ONE MONTH INDUSTRIAL TRAINING ON

“MICROCONTROLLER BASED SYSTEM DESIGN” FROM OUR

INSTITUTE.

I WISH HIM ALL SUCCESS IN LIFE.

______________________________

AUTHORISED SIGNATURE WITH SEAL

(MICROPRO TRAINING CENTER)

75C, Park Street, 4th Floor, Kolkata-700 016 Phone: 033-40648262

Acknowledgement

First of all, we express our gratitude to

our teacher and project guide Mr. Mangalik Pal,

Trainer of ‘Micropro Training Center’, without

whom it would have been impossible to complete

our project.

And secondly, I would like to thank our

group members and friends who supported each

other to make the project a success.

PREFACE

OVERVIEW

A counter is a device which stores(sometimes displays) the

number of times a particular event or process has occurred,

often in relationship to a clock signal. Unlike a counter, that can

change state in only one direction, under the control of a down

selector input, is known as a Down Counter. Generally it starts

counting from a predefined value called SET VALUE, and then

starts down counting until it goes to the zero, means maximum

counting and end the process.

The down counter is used in various places of our regular

life. For an example a semi-automated car parking lot gate use

Down Counter for counting the number of cars enter or exit. And

when enter cars reach the limit of capacity of parking place; the

entrance gate is lock showing ‘NO VACANT PLACE HERE’.

Why we Use AT89C51?

The AT89C51 is a low power, high performance CMOS 8-bit

microcomputer with 4 bytes of Flash Erasable & Progra-mmable

Read Only Memory (EPROM). The device is manufacture using

Atmel’s high density non-volatile memory technology and

compatible with the industry standard MCS-51 instruction-set

and pin-out.

The on chip flash memory allows the program memory to

be programmed in system or by a conventional non-volatile

memory programmer, by combining a versatile 8-bit CPU with

flash on a monolithic chip. The Atmel AT89C51 is a powerful

microcomputer which provides a highly flexible and cost

effective solution to many embedded control applications.

The AT89C51 provides the following standard features:

Compatible with MCS-51 products

4KB in-system reprogrammable Flash Memory

Full static operation: 0HZ to 24MHZ

Three level program Memory Lock

128×8 bit internal RAM

32 programmable I/O lines

Two 16-bit Timer/Counter

Six Interrupts sources

Programmable serial channel

Low power idle and power down modes.

In addition the AT89C51 is designed with static logic for

operation Down-to-Zero frequency and supports and two

software selectable power saving modes. The Idle mode stops

the CPU, while other allowing the RAM, Timer/Counters.

Architecture:

8051µc is a 8bit microcontroller introduced by Intel Corporation in 1981 which comes in

40 pin dual inline package (DIP).

It has 4KB of inbuilt ROM i.e. on chip program space.

It has 128bytes of inbuilt RAM space and if required external memory of 64KB can be

interfaced to the microcontroller.

There are 4 parallel 8bit ports namely port 0, port 1, port 2 and port 3 which are

addressable as well as programmable.

It has an on chip crystal oscillator with crystal frequency 11.0592MHz (~12MHz).

It has full duplex serial I/O port having two pins namely TxD, RxD.

It has two 16bit timers namely Timer 0 and Timer 1 which can be used either as timer for

internal operation or as counter for external operation.

It has five interrupt sources. All of them are maskable as well as vector interrupts. They

are External Interrupt 0, Timer Interrupt 0, External Interrupt 1, Timer Interrupt 1, and

Serial Port Interrupt.

The programming mode of this microcontroller consists of general purpose registers

(GPRs), Special Purpose Registers (SPRs) and Special Function Registers (SFRs).

The instruction set of 8051 µc consists of more number of bit manipulations or Boolean

variable manipulation group of instructions. The instructions are very much useful to

manipulate SFR bits and also port pins.

Register and Internal RAM organization:

8051 µc provides two 8bit general purpose registers – A (Accumulator) and B.

It provides 4 special purpose registers – 16bit Program Counter (PC), 8bit Stack Pointer

(SP), 16bit Data Pointer and 8bit Program Status Word (PSW).

It also provides few Special Function Registers. They are TMOD, TCON, IE, IP,

SBUF, SCON, and PCON.

The 128bytes on chip RAM of 8051 µc is divided into three portions as given below.

o 00H – 1FH : These 32bytes are arranged as 4 register banks namely Bank 0, Bank 1,

Bank 2, Bank 3 where each bank consists of 8 registers namely R0 through R7

o 20H – 2FH : These 16bytes (128bits) are made available as bit-addressable

bytes.

o 30H – 7FH : These 80 bytes are available as scratch-pad RAM bytes

Pin diagram:

Power Supply pins

8051 µc works with +5V DC source applied to Vcc and 0V to Gnd input pin. It has an

on chip crystal clock generator. As such it must be supported externally by connecting a

crystal across crystal input XTAL1, XTAL2. It has active high reset input pin. As such the

controller is said to be reset upon application of active high pulse.

I/O port pins

A total number of 32 I/O pins are provided as port pins divided into 4 ports – port 0,

port 1, port 2 and port 3. All ports are both byte and bit addressable. All ports are

programmable. All the ports act as simple input/output ports. All the ports except port 1

offer alternate functions. They are as follows.

o Port 0 and Port 2: If input pin is grounded then port 0 acts as lower order 8bit

address data bus whereas port 2 acts as higher order 8 bit address bus.

o Port 3: Each and every pin in this port offer some separate functionality

irrespective of level at input pin

Pin Special Function

P3.0 RxD (Serial Input pin)

P3.1 TxD (Serial Output pin)

P3.2 (Interrupt 0 input pin)

P3.3 (Interrupt 1 input pin)

P3.4 (Timer 0 input if timer is counter)

P3.5 (Timer 1 input if timer is counter)

P3.6 (RAM write control signal output)

Instruction-Set of 8051:

The instruction-set of 8051 microcontroller are divided in

five major groups-

Arithmetic Operations

Logic Operations

Data Transfer Operations

Boolean Algebraic Operations

Program and Machine Control Operations

Arithmetic Operations: ♦ With arithmetic instructions, the C8051 CPU have no special knowledge

of the data format (e.g. signed/unsigned binary, binary coded decimal, ASCII, etc.)

♦ The appropriate status bits in the PSW are set when specific conditions are met, which allows the user software to manage the different data formats (carry, overflow etc…)

This group of operators performs arithmetic operations. Arithmetic

operations affect the flags, such as Carry Flag (CY), Overflow Flag (OV) etc., in

the PSW register.

Logic Operations: ♦ Logical instructions perform Boolean operations (AND, OR, XOR, and

NOT) on data bytes on a bit-by-bit basis

Logical instructions perform standard Boolean operations such as AND,

OR, XOR, NOT (compliment). Other logical operations are clear accumulator, rotate accumulator left and right, and swap nibbles in accumulator.

Data Transfer Operations: ♦ Data transfer instructions can be used to transfer data between an

internal RAM location and an SFR location without going through the accumulator

♦ It is also possible to transfer data between the internal and external RAM by using indirect addressing

Data transfer instructions are used to transfer data between an internal

RAM location and SFR location without going through the accumulator. Data can also be transferred between the internal and external RAM by using indirect addressing.

Boolean Algebraic Operations: ♦ The C8051 processor can perform single bit operations ♦ The operations include set, clear, and, or and complement instructions ♦ Also included are bit–level moves or conditional jump instructions

The Boolean Variable operations include set, clear, as well as and, or and

complement instructions. Also included are bit–level moves or conditional jump instructions. All bit accesses use direct addressing

Program and Machine Control Operations: ♦ Program branching instructions are used to control the flow of program

execution

Program branching instructions are used to control the flow of actions in a

program. Some instructions provide decision making capabilities and transfer control to other parts of the program e.g. conditional and unconditional branches.

The 8051 Assembler, Linker & Simulator: Assembler: The 8051 Assembler is an application, which

generate an object (.obj) file of an assembly (.asm) Language file.

Linker : The 8051 Linker is an application, which generate a HEX file(.hex) of an object file (.obj). The output file format is as Intel Hex. Simulator: The 8051 Simulator contain itself resistors, ports,

RAM memory etc. It also contains Program Counter (PC), Stack Pointer (SP), General Purpose Resistors, PSW, DPTR etc.

It enables us to read the HEX code of a file, positions of their in Stack and Program Counter, run the program and after that shows the content of RAM, Resistor, PSW etc. It also enables to load data to RAM or Registers.

To read a HEX code the command is: RHC To load the data into the registers: MI R0=#DATA

Algorithm of Down Counter: Step 01: Define the BIT and BYTE memory location for all Switches, Down Counter and Set-Point value. Step 02: Set the Microcontroller as ‘counter mode’. Step 03: Set the P1.3 pin for output by clear it. Step 04: Ready Switch: Ready all switches to connect with 0, 1, 2 pin of PORT-1. Step 05: Fix-Set-Point:

(i)Check if SW1 is pressed or not. If pressed, go to Next step either repeat this step. (ii) Check if SW2 is pressed or not. If pressed, Increment Set-Point, either go to Next step. (iii) Check if SW3 is pressed or not. If pressed, Decrement Set-Point, either go to step 5(i).

Step 06: Down Counting: Starts Down counting from the Set- Point. The maximum counting value is ZERO (0).

Step 07: Display: (i) Check whether SW1 is pressed or not. If pressed go to step 7(ii), either go to step 7(iii). (ii) Convert the set-point from binary to decimal and

Store it to RAM memory. (iii)Convert the Down-counter value from binary to Decimal and store it to RAM memory.

Step 08: Relay: Check the Down-Counter value. If it is zero (0) Turn-on the Relay either continues. Step 09: Reset: Check if both SW2 and SW3 are pressed or

not. If both pressed reset the counter to its Set-Point, Either continues.

Step 10: Delay: Enter a Delay program as desire. Step 11: Go to Step 4.

Steps to Develop a Program:

At first we should store the 8051 simulator files on a directory in the computer in any drive.

01. Open the command prompt window from Start>all program>accessories>command prompt

02. Go to that directory where the simulator files are stored, using change directory command.

03. Type ‘EDIT’ and hit Enter. 04. Give (one Enter + one Space) or (one Enter + one Tab) 05. Write the assembly language program and save it as ‘.ASM’

extension. 06. Go to File>Exit. 07. Open the assembler by type ‘X8051.EXE‘and hit Enter. 08. Give the input file name with extension and hit Enter. Then

give the output file name if you want and hit Enter. It assembles the input file, shows the errors if any and make an object file.

09. Type ‘L8051.EXE’ (or LINK4.EXE) and hit Enter. 10. Give the input file name as NAME.OBJ, Offset for code,

multiple input, and output and library name if you want. Give ‘m’ (Microtech) in the option and hit Enter. It generates a HEX file of the input object file.

11. Type ‘S8051.EXE’ and hit Enter. It shows the simulator. 12. Type ‘RHC’ and hit Enter. Then enter input file name to

read the HEX code of that file. 13. Hit Enter for several times. There will be change in

Resistors, RAM etc. in every Enter. 14. To store a data in resistors type

MI Resistor name=#Data. By this method an 8051 program is developed and after running the program what is the content of resistors, RAM etc. it shows that.

Program of Down-Counter: ;************************************************/ ;*************BYTE MEMORY LOCATION *************/ DOWN_COUNTER: EQU 30H SET_POINT: EQU 31H ;************************************************/ ;**************BIT MEMORY LOCATION ************/ SW1: EQU 7FH SW2: EQU 7EH SW3: EQU 7DH ;************************************************/ ;***********************************************/ .CHIP 8051 .SYMBOLS ORG 00H LJMP START ;************************************************/ ;************************************************/

ORG 100H START: MOV TMOD,#05H CLR P1.3

LOOP1: NOP LCALL READ_SWITCH LCALL FIX_SET_POINT LCALL CAL_DOWN_COUNTER LCALL DISPLAY_DRIVE LCALL RELAY_DRIVE LCALL RESET_COUNTER LCALL DELAY SJMP LOOP1 ;************************************************/

;************************************************/ READ_SWITCH: SETB P1.0 MOV C, P1.0 CPL C MOV SW1,C SETB P1.1 MOV C, P1.1 CPL C MOV SW2,C SETB P1.2 MOV C, P1.2 CPL C MOV SW3,C RET ;************************************************/ ;************************************************/

FIX_SET_POINT: JNB SW1, QUIT1 JNB SW2,DECREMENT CLR C MOV A,SET_POINT SUBB A,#0C8H ; SET POINT SHOULD BE <=200 DEC JNC QUIT1 INC SET_POINT SJMP QUIT1 DECREMENT: JNB SW3,QUIT1 MOV A,SET_POINT ; SET POINT SHOULD BE >=00 DEC JZ QUIT1 DEC SET_POINT QUIT1: RET ;************************************************/

;************************************************/ CAL_DOWN_COUNTER: CLR C MOV A,SET_POINT SUBB A,TL0 MOV DOWN_COUNTER,A RET ;************************************************/ ;************************************************/

DISPLAY_DRIVE: JB SW1,DISPLAY_SP MOV 60H,DOWN_COUNTER ; 60H INPUT BIN DATA LCALL BIN2DEC ; 61H HUND MOV A,62H ; 62H TEN SWAP A ; 63H UNIT ORL A,63H MOV P0,A MOV P2,61H SJMP QUIT2 DISPLAY_SP: MOV 60H,SET_POINT ; 60H INPUT BIN DATA LCALL BIN2DEC ; 61H HUND MOV A,62H ; 62H TEN SWAP A ; 63H UNIT ORL A,63H MOV P0,A MOV P2,61H

QUIT2: RET ;************************************************/ ;************************************************/

BIN2DEC: MOV A,60H MOV B,#64H DIV AB MOV 61H,A ; HUND MOV A,B

MOV B,#0AH DIV AB MOV 62H,A ; TEN MOV 63H,B ; UNIT

QUIT3: RET ;************************************************/ ;************************************************/

RELAY_DRIVE: JNB TCON.4,QUIT4 MOV A,DOWN_COUNTER JZ RELAY_ON CLR P1.3 SJMP QUIT4 RELAY_ON: SETB P1.3 CLR TCON.4

QUIT4: RET ;************************************************/ ;************************************************/

RESET_COUNTER: JB SW1,QUIT5 JNB SW2,QUIT5 JNB SW3,QUIT5 MOV TL0,#00H MOV TH0,#00H SETB TCON.4

QUIT5: RET ;************************************************/ ;************************************************/

DELAY: MOV R7,#0FFH L1: MOV R6,#0FFH L2: NOP DJNZ R6,L2 DJNZ R7,L1 RET ;****************END OF THE PROGRAM*************/

Block Diagram of Down-Counter:

Functional Description of Down-Counter:

1. The equipment has three ‘seven segment display’ and three push-to-on switches (SW1-SW3) as user interface.

2. If no switches are pressed the running counter value is displayed.

3. If SW1 is pressed set-point for batch count will be displayed.

4. To increment set-point press SW2, while pressing down SW1. Upper limit for set-point is 200

5. To decrement set-point press SW3, while pressing down SW1. Lower limit for set-point is 0.

6. If counter value is zero, Relay will be ON, indicating end of batch. Counting also stop.

7. If both SW2, SW3 are pressed, counter starts down counting from set-point again (Reset).

Circuit Diagram:

Use of Equipment:

While making our project, we use the following components in our circuit –

Counting Section- IC AT89C51-1 Piece Input Section- Push-Button-Switch-3 piece Output Section- Seven-Segment display-3 piece

Light emitting diode-1 piece Power Section- IC 7805 (5V Regulator)-1 piece

IC 7812 (12V Regulator)-1 piece Discrete components- Capacitors- 10µF-3 piece

33Pf- 2 pieces 0.1 µF- 4 pieces

1000µF- 2 pieces Resistors- 10kΩ- 2 piece 15kΩ- 1 piece 2.2kΩ- 1 piece 470Ω-21 pieces Diode- IN4007-5 piece Pull-Up Resistor- 1 piece Other Components- IC 7447(ADC) - 3 piece Crstal-10MHZ-1 piece Transistor-2N2222A-1 piece Relay (12 V, 1 C/O) 1 piece Connectors- 2 pin Relimate -4 piece 5 pin relimate-4 piece Heat-Sink for IC7805- 1 piece

Conclusion: Performance of the circuit- The circuit of our project, which we deigned, is working properly with a negligible error. The error is mainly due to loose contacts of the components used. But we correct these later. Then the circuit starts running correctly. Scope of Further Improvement: This circuit is designed to count from 0 to 200 or vice versa. We can further improve our circuit by changing the program and using some extra components.