BCD to Binary Converter
This project shows the BCD code to Binary code convertion process using PIC16C55. To simulate this circuit, 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 chip , 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 one 8 bit input and one 16 bit out put .For implementing this a network of 74245 is designed according to the control pins DIR1, G/INB, DIR2, G/INC from PORTA . PORTB and PORTC acts as input port or output port. BCD code is read through PORT B by setting 74245 networks in input mode.
HPDL 1414 control signals D0, D1, D2, D3 are given through PORTB and A0, A1, D4, D5, D6, WR are given through PORT C by setting 74245 networks in output mode.
HPDL1414 display shows result of conversion, first two digits are BCD code and last two digits are its equivalent binary code.
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
bcd RES 1 ;bcd variable definition
binary RES 1 ;binary variable declaration
bcdlsb RES 1 ;bcdlsb variable declaration
bcdmsb RES 1 ;bcdmsb variable declaration
multiplicand RES 1 ;multiplicand varible declaration
multiplier RES 1 ;multiplier variable declaration
result RES 1 ;result variable declaration
count RES 1 ;count 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
;**********************************************************************
MAIN CODE 0x000
start
;read bcd value to bcd through port b
;port reading
clrw ;clear accumulator
TRIS PORTA ;Set PORT A as output
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 portb b to accumulator
movwf bcd ;move accumulator to bcd
;display bcd value
;hpdl 1414 implementation -------- 74245 as output mode
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
;second digit
movlw 0x0f ;move literal value to accumulator
andwf bcd,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
movlw 0xf0 ;move literal value to accumulator
andwf bcd,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
;separate bcd to bcd msb and bcd lsd
movlw 0x0f ;move literal value to accumulator
andwf bcd,0 ;and bcd with accumator and output in accumulator
movwf bcdlsb ;move accumulator to bcdlsb
movlw 0xf0 ;move literal value to accumulator
andwf bcd,0 ;and bcd with accumulator and output in accumulator
movwf bcdmsb ;move accumulator to bcdmsb
swapf bcdmsb,1 ;swap and result in bcdmsb
;conversion algorithm
movf bcdmsb,0 ;move bcdmsb to accumulator
movwf multiplicand ;move accumulator to mulitplicand
movlw 0xa ;move literal value to accumulator
movwf multiplier ;move accumulator to mulipiler
call multiplication ;for multiplying bcdmsb by 0xa
movf bcdlsb,0 ;move bcdlsb to accumulator
addwf result,1 ;add accumulator with result and store in result
;display result to hpdl 1414
;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 store the 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
repeat goto repeat ;infinite loop
multiplication
clrw ;clear accumulator
movwf result ;move accumulator to result
incf multiplier,1 ;increment multiplier by 1 and store in multiplier
movf multiplier,0 ;move multiplier to accumulator
movwf count ;move multiplier value to count
loop decfsz count,1 ;decrement count and test is zero if yes then skip
goto addition ;goto addition
retlw 0 ;return subroutine
addition
movf multiplicand,0 ;move multiplicand to accumulator
addwf result,1 ;add result with accumulator
goto loop ;goto loop
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.