Multiplication and Division using PIC Microcontroller

This project shows the multiplication and division process using PIC16C55. To simulate circuit in this project, initially activate Mixed Mode simulator from the Schematic Editor window. Simulation can be performed by selecting Run Transient analysis (Oscillograph) from Simulation menu.

The circuit contains a PIC16C55, a voltage source, 74LS245 Octal 3-state bus transceiver,7404 NOT gate, HPDL-1414 Four Character Alphanumeric Display.

PIC 16C55 has only two 8 bit port and one 4 bit port. This circuit require two 8 bit input and one 16 bit out put .For implementing this a network of 74245 is designed according to the control pins DIR1, DIR2 from PORTA. PORTB and PORTC act as input port or output port.

According to the MODE control the circuit is perform multiplication and division. MODE control pin ids read through RA0.if MODE is high then multiplication is performing other wise division perform.

MODE = 1 (Multiplication)

Multiplicand is read through PORT B and multiplier through PORTC by setting 74245 networks in input mode. HPDL1414 display shows result of multiplication.

MODE = 0 (Division)

Dividend is read through PORT B and divisor through PORTC by setting 74245 networks in input mode. HPDL1414 display shows result of division. First two digits are quotient and last two digits are remainder.

The source code written in Assembly language can be viewed from the code editor window

The program is as shown:

#include p16c5x.inc

; VARIABLE DEFINITIONS

temp_var udata

multiplicand res 1 ;multiplicand varible declaration

multiplier res 1 ;multiplier variable declaration

result res 1 ;result variable declaration

count res 1 ;count declaration

resultmsb res 1 ;resultmsb variable declaration

dig0 res 1 ;dig0 variable declaration

dig1 res 1 ;dig1 variable declaration

dig2 res 1 ;dig2 variable declaration

dig3 res 1 ;dig3 variable declaration

control res 1 ;control variable declaration

mode res 1 ;mode variable declaration

dividend res 1 ;dividend variable definition

divisor res 1 ;divisor variable definition

quotient res 1 ;quotient variable definition

remainder res 1 ;remainder variable definition

counter res 1 ;counter variable definition

dividend_d res 1 ;dividend_d variable definition

remainder_1 res 1 ;remainder_1 variable definition

;********************************************************************

reset_vector code 0x1ff ;processor reset vector

goto start

MAIN CODE 0x000

start

;read 0 the pin of port A

;set PORTA <1:0> as input

;set PORTA <3:2> as output

;bit pattern is 0011(0x03) 0 for output and 1 for input

movlw 0x03 ;move literal value to accumulator

tris PORTA ;set PORTA <1:0> as inpu, set PORTA <3:2> as output

;check multiplication or division

;read PORTA <0>

movf PORTA,0 ;move PORT A to accumulator

movwf mode ;move accumulator to mode

;if mode<0> is 0 then division

;if mode<0> is 1 then multiplication

;check mode <0> is 0 if yes call division

btfss mode,0 ;skip if mode<0> is one

goto division ;goto nochange

;multiplication

;port reading

movlw 0x00 ;move literal value to accumulator

movwf PORTA ;move accumulator to PORT A

movlw 0xff ;move literal value to accumulator

tris PORTB ;Set PORT B as input

movf PORTB,0 ;move PORT B to accumulator

movwf multiplicand ;move accumulator to multiplicand

movlw 0xff ;move literal value to accumulator

tris PORTC ;Set PORT C as input

movf PORTC,0 ;move PORT C to accumulator

movwf multiplier ;move accumulator to multiplier

call multiplication ;call sub routine muiltiplication

call display

goto repeat

;*******************************************************************************A

;port reading

division movlw 0x0 ;move literal value to accumulator

movwf PORTA ;move accumulator to port A

movlw 0xff ;move literal value to accumulator

tris PORTB ;Set port B as input

movf PORTB,0 ;move port B to accumulator

movwf dividend ;move accumulator to dividend

movlw 0xff ;move literal value to accumulator

TRIS PORTC ;Set PORT C as input

movf PORTC,0 ;move PORT C to accumulator

movwf divisor ;move accumulator to divisor

movlw 0x5 ;move literal value to accumulator

movwf counter ;move accumulator to counter for initialize

clrw ;clear accumulator

movwf quotient ;move accumulator to quotient

movwf remainder ;move accumulator to remainder

loop1 bcf STATUS,0 ;clear carry

movf dividend,0 ;move dividend to accumulator

movwf dividend_d ;move accumulator to dividend_d

;shift right it by 4

rrf dividend_d,1 ;right shift

rrf dividend_d,1 ;right shift

rrf dividend_d,1 ;right shift

rrf dividend_d,1 ;right shift

;mask msb by 0

movlw 0x0f ;move literal value to accumulator

andwf dividend_d,1 ;AND accumulator with the dummy dividend, inorder to mask msb of dummy dividend.

;Comparison

movf divisor,0 ;move divisor to accumulator

subwf dividend_d,1 ;subtract accumulator with the dividend_d

btfsc STATUS,0 ;skip next statement if result is negative

call subtraction

rlf quotient,1 ;shift left the quotient

movf dividend,0 ;move dividend to accumulator

movwf dividend_d ;move dividend to its dummy

bcf STATUS,0 ;clear carry

rlf dividend,1 ;shift left the dividend

decfsz counter,1 ;decrement and skip if zero

goto loop1 ;check counter

movf dividend_d,0 ;move dividend_d to accumulator before shifting

movwf remainder ;move dividend_d to remainder

bcf STATUS,0 ;clear carry

rrf remainder,1 ;right shift

rrf remainder,1 ;right shift

rrf remainder,1 ;right shift

rrf remainder,1 ;right shift

;move remainder to result

;move quotient to resultmsb

movf remainder,0 ;move remainder to accumulator

movwf result ;move accumulator to remainder

movf quotient,0 ;move quotient to accumulator

movwf resultmsb ;move accumulator to resultmsb

call display

goto repeat ;infinite loop

subtraction

movlw 0x0f ;move literal value to accumulator

andwf dividend,1 ;AND accumulator with the dividend, inorder to mask msb of dividend.

bcf STATUS,0 ;clear carry

rlf dividend_d,1 ;left shift

rlf dividend_d,1 ;left shift

rlf dividend_d,1 ;left shift

rlf dividend_d,1 ;left shift

movlw 0xf0 ;move literal value to accumulator

andwf dividend_d,1 ;AND accumulator with the dummy dividend, inorder to mask lsb of dummy dividend.

movf dividend_d,0 ;move dividend_d to accumulator

addwf dividend,1 ;add accumulator with the dividend and store the result in divident

bsf STATUS,0 ;set carry

clrw ;clear accumulator

tris PORTB ;set port B as output port

movf dividend,0 ;move dividend to accumulator

movwf PORTB ;write the result to port B

retlw 0

tepeat goto repeat ;infinite loop

multiplication clrw ;clear accumulator

movwf result ;move accumulator value to result

movwf resultmsb ;move accumulator value to result msb

incf multiplier,1 ;increment multiplier by 1 and store in multiplier

movf multiplier,0 ;move multiplier value to accumulator

movwf count ;move accumulator value to count

loop

decfsz count,1 ;decrement count and test is zero if yes then skip

goto addition

retlw 0 ;return subroutine

addition movf multiplicand,0 ;move multiplicand to accumulator

addwf result,1 ;add multiplicand to result and stored in result

btfsc STATUS,0 ;if carry is zero then skip

ncf resultmsb,1 ;if carry then increment msb by 1

clrw ;clear accumulator

goto loop

;******************************************************************************

;hpdl 1414 implementation

;74245 as output mode

display movlw 0xf ;move literal value to accumulator

movwf PORTA ;move accumulator TO port A

movlw 0x00 ;move literal value to accumulator

tris PORTB ;Set PORT B as output

movlw 0x00 ;move literal value to accumulator

tris PORTC ;Set PORT C as output

;display of DIG0

;Set 74245 in output mode

;separation of zeroth digit

movlw 0x0f ;move literal value to accumulator

andwf result,0 ;AND result with accumulator and store the output in accumulator

movwf dig0 ;move accumulator to dig0

;check digit is greater than 9

movlw 0x09 ;move literal value to accumulator

subwf dig0,0 ;subtract 9 from dig0 and result in accumulator

btfss STATUS, 0 ;skip if carry flag is 1

goto nochange ;goto nochange

btfsc STATUS,2 ;skip if zero flag is zero, ie result is non zero

goto nochange ;goto nochange

movlw 0x09 ;move literal value to accumulator

subwf dig0,1 ;subtract 9 from dig0 and result in dig0

movlw 0x13 ;move literal value to accumulator

movwf control ;move control to accumulator

goto porting0 ;goto porting 0

nochange movlw 0x0f ;move literal value to accumulator

movwf control ;move control to accumulator

porting0 movf dig0,0 ;move dig0 value to accumulator

movwf PORTB ;move accumulator to portB

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

movlw 0xff ;move literal value to accumulator

movwf control ;move control to accumulator

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

;zeroth digit complete

;first digit ---------- separation of first digit

movlw 0xf0 ;move literal value to accumulator

andwf result,0 ;AND result with accumulator and output in accumulator

movwf dig1 ;move accumulator to dig1

swapf dig1,1 ;swap and result in dig1

;check digit is greater than 9

movlw 0x09 ;move literal value to accumulator

subwf dig1,0 ;subtract 9 from dig1 and result in accumulator

btfss STATUS, 0 ;skip if carry flag is 1

goto nochange1 ;goto nochange1

btfsc STATUS,2 ;skip if zero flag is zero, ie result is non zero

goto nochange1 ;goto nochange1

movlw 0x09 ;move literal value to accumulator

subwf dig1,1 ;subtract 9 from dig1 and result in dig1

movlw 0x12 ;move literal value to accumulator

movwf control ;move control to accumulator

goto porting1 ;goto porting 1

nochange1 movlw 0x0e ;move literal value to accumulator

movwf control ;move control to accumulator

porting1 movf dig1,0 ;move dig1 value to accumulator

movwf PORTB ;move accumulator to portB

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

movlw 0xff ;move literal value to accumulator

movwf control ;move control to accumulator

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

;separation of second digit

movlw 0x0f ;move literal value to accumulator

andwf resultmsb,0 ;AND resultmsb with accumulator and output in accumulator

movwf dig2 ;move accumulator to dig2

;check digit is greater than 9

movlw 0x09 ;move literal value to accumulator

subwf dig2,0 ;subtract 9 from dig2 and result in accumulator

btfss STATUS, 0 ;skip if carry flag is 1

goto nochange2 ;goto nochange2

btfsc STATUS,2 skip if zero flag is zero, ie result is non zero

goto nochange2 ;goto nochange2

movlw 0x09 ;move literal value to accumulator

subwf dig2,1 ;subtract 9 from dig2 and result in dig2

movlw 0x11 ;move literal value to accumulator

movwf control ;move control to accumulator

goto porting2 ;goto porting 2

nochange2 movlw 0x0d ;move literal value to accumulator

movwf control ;move control to accumulator

porting2 movf dig2,0 ;move dig2 value to accumulator

movwf PORTB ;move accumulator to portB

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

movlw 0xff ;move literal value to accumulator

movwf control ;move control to accumulator

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

;second digit complete

;third digit -------------- separation of third digit

movlw 0xf0 ;move literal value to accumulator

andwf resultmsb,0 ;AND resultmsb with accumulator and output in accumulator

movwf dig3 ;move accumulator to dig3

swapf dig3,1 ;swap and result in dig3

;check digit is greater than 9

movlw 0x09 ;move literal value to accumulator

subwf dig3,0 ;subtract 9 from dig3 and result in accumulator

btfss STATUS, 0 ;skip if carry flag is 1

goto nochange3 ;goto nochange3

btfsc STATUS,2 ;skip if zero flag is zero, ie result is non zero

goto nochange3 ;goto nochange3

movlw 0x09 ;move literal value to accumulator

subwf dig3,1 ;subtract 9 from dig3 and result in dig3

movlw 0x10 ;move literal value to accumulator

movwf control ;move control to accumulator

goto porting3 ;goto porting 3

nochange3 movlw 0x0c ;move literal value to accumulator

movwf control ;move control to accumulator

porting3 movf dig3,0 ;move dig3 value to accumulator

movwf PORTB ;move accumulator to portB

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

movlw 0xff ;move literal value to accumulator

movwf control ;move control to accumulator

movf control,0 ;move control value to accumulator

movwf PORTC ;move accumulator to port C

;testing

;goto repeat

retlw 0

;testing

end ; directive 'end of program'

The source code in the code editor window has to be compiled after making any modifications

(editing). Also the code can be debugged during simulation.