In the partial fulfillment of the course

INSTR/EEE 241 – Microprocessor Programming & Interfacing

BITS- Pilani K.K.Birla Goa Campus

Project by:

NAVYA (2011A3PS240G) VAMSI REDDY (2011A8PS346G)

OMPRAKASH REDDY (2011A8PS317G) GAUTHAM REDDY (2011A8PS364G)

Problem statement:

PROBLEM NO :11

System to be designed: microwave oven

5 different power levels (100%, 80%, 60%, 40%, and 20%)

Time of cooking divided into 10 sec slots

Time set as multiple of 10 min, 1 min or 10 sec

Time is to be displayed

Door gets locked when cooking begins and should open when cooking is

aborted

When stop pressed once, cooking aborted, timer not cleared

Second press of stop clears the timer

When time becomes zero, buzzer starts and will stop only if stop button is

pushed.

If quick start (pushing start button without setting time and power) is

pressed, default power taken(100%) and time as 30sec , which gets

incremented upon further press of start button

ASSUMPTIONS MADE:

1. User cannot set the time more than 99:59 min.

2. If the user has set the time then he can press start button only once.

However, if he did not enter the time then he can press start/quick start

any no. of times.

3. The door will automatically get locked once the user presses start/quick

start and will open when the process gets completed.

4. LED will work according to the power mode. Ex- If power is 80% then the

time will be divided in 10s slots and LED will be on for 8sec and off for 2 sec.

5.Multiple keys cannot be pressed simultaneously

COMPONENTS USED:

1) 89C51 MICROCONTROLLER

2) 7447 IC

3) 4 SEVEN SEGMENT DISPLAYS

4) 4 TRANSISITORS

5) PIEZO BUZZER

6) 6 PUSH BUTTONS

7) 12 MHZ CLOCK CRYSTAL

8) ONE LED

9)2 RESISTORS

CIRCUIT DIAGRAM

FLOWCHART:

No Yes

Yes

No

No

Yes

Yes

No

Yes

No

Yes Yes

No

No No

No

Yes

Port initialization

No. of presses : POWER

button(n)

n<=5

Power = [100-(n-1)20]% n=n-5

Stop

Time Set

Set timer: n1-10min,

n2-min ,n3-10 sec

Total Time = n1*600 + n2*60 + n3*10 (sec)

7 Segment Display(Time)

Start

Display countdowntime & Set power

led on for 12-2n (sec) & off for 2n-2

(sec) for every 10 sec slot

Stop

Countdown Time=0

BUZZER

Stop

Start

Quick Start

Power = 100%

Stop

Start

Time = Time + 30 (sec)

Display countdown time

& Set power led

Start

Stop

Countdown Time=0

BUZZER

ALP CODE:

SEL_DISA EQU P1.0

SEL_DISB EQU P1.1

SEL_DISC EQU P1.2

SEL_DISD EQU P1.3

START EQU P1.4

STOP EQU P1.5

TEN_MIN EQU P1.6

ONE_MIN EQU P1.7

TEN_SEC EQU P3.0

POWER EQU P3.1

BUZZ EQU P3.7

ORG 0000H

MAIN:

CLR BUZZ

SETB SEL_DISA

SETB SEL_DISB

SETB SEL_DISC

SETB SEL_DISD

MOV R0,#1

MOV R1,#0 ;FOR 10_MIN

MOV R2,#0 ;FOR 1_MIN

MOV R3,#0 ;FOR 10_SEC

MOV R4,#0 ;FOR 1_SEC

MOV R5,#0 ;FOR START

MOV R6,#0 ;POWER

;WAIT FOR POWER BUTTON TO BE PRESSED

W1: MOV R7,#20

JB POWER,$

MOV R5,A

ADD A,#1

MOV A,R5

CJNE R5,#6,W2

MOV R5,A

SUBB A,#5

MOV A,R5

W2:

ACALL DELAY

DEC R7

CJNE R7,#00,W2

JB START,X6

JB TEN_MIN,X10

JB ONE_MIN,X10

JB TEN_SEC,X10

JMP W1

;SETTING TIME FOR TIMER NORMAL MODE

X10: JB START,X6

MOV R7,#20H

X11:JNB TEN_MIN,X7

SETB SEL_DISA

CLR SEL_DISB

CLR SEL_DISC

CLR SEL_DISD

INC R1

MOV P2,R1

X7:JNB ONE_MIN,X8

CLR SEL_DISA

SETB SEL_DISB

CLR SEL_DISC

CLR SEL_DISD

INC R2

MOV P2,R2

X8:JNB TEN_SEC,X9

CLR SEL_DISA

CLR SEL_DISB

SETB SEL_DISC

CLR SEL_DISD

INC R3

MOV P2,R3

X111: ACALL DELAY

DEC R7

CJNE R7,#00,X111

X9:JMP X10

;SETTING TIME FOR TIMER USING QUICK START MODE

JNB START,X13

INC R5

MOV R7,#20

S1:ACALL DELAY

DEC R7

CJNE R7,#00,S1

X13:

MOV A,R5

MOV B,#2

DIV AB

MOV A,B

CJNE A,#00,X21

MOV A,R3

ADD A,#03

MOV R3,A

X21:

MOV A,R5

MOV B,R0

DIV AB

CJNE A,#1,X22

MOV A,R0

ADD A,#2

MOV R0,A

X22:

MOV A,R5

MOV B,#20

DIV AB

MOV A,B

CJNE A,#00,X23

MOV A,R1

ADD A,#1

X23:

X6:

;RUNNING TIMER

X3:JB STOP,A1

MOV R4,#09

X2:MOV R7,#20

X1:SETB SEL_DISA

CLR SEL_DISB

CLR SEL_DISC

CLR SEL_DISD

MOV A,R1

MOV P2,A

CLR SEL_DISA

SETB SEL_DISB

CLR SEL_DISC

CLR SEL_DISD

MOV A,R2

MOV P2,R2

CLR SEL_DISA

CLR SEL_DISB

SETB SEL_DISC

CLR SEL_DISD

MOV A,R3

MOV P2,A

CLR SEL_DISA

CLR SEL_DISB

CLR SEL_DISC

SETB SEL_DISD

MOV A,R4

MOV P2,A

ACALL DELAY

DEC R7

CJNE R7,#00,X1

DEC R4

CJNE R4,#00,X2

ACALL POW

DEC R3

CJNE R3,#00,X3

MOV R3,#05

DEC R2

CJNE R2,#00,X3

MOV R3,#05

MOV R2,#09

DEC R1

CJNE R1,#00,X3

SETB BUZZ

A1:

POW:

MOV R7,#20

MOV A,R5

MOV B,#2

MUL AB

MOV R6,A

MOV A,#12

SUBB A,R6

Y1:ACALL DELAY

DEC R7

CJNE R7,#00,Y1

MOV R7,#20

MOV A,R5

MOV B,#2

MUL AB

MOV R6,A

SUBB A,#2

Z1:ACALL DELAY

DEC R7

CJNE R7,#00,Z1

RET

;DELAY OF 50 MSEC

DELAY:

MOV TMOD,#01H

MOV TH0,#3CH

MOV TL0,#0B0H

MOV R7,#00H

SETB TR0

DEL: JNB TF0,DEL

CLR TF0

RET

END