Binary to BCD Converter
This project shows the Binary code to BCD code conversion 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 and 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 act as input port or output port. Binary 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 equivalent BCD 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
BINARY RES 1 ; Binary input
DBINARY RES 1 ; Dummy binary
BCD100 RES 1 ; BCD 100th position
BCD10 RES 1 ; BCD 10th position
BCD1 RES 1 ; BCD 1st position
LBCD RES 1 ; local BCD declaration
POWER RES 1 ; BCD 1st position
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
;**********************************************************************
RESET_VECTOR CODE 0x1FF ; processor reset vector
goto start
MAIN CODE 0x000
start clrw ;clear accumulator
movwf BCD1 ;store 0 to BCD1
movwf BCD10 ;store 0 to BCD10
movwf BCD100 ;store 0 to BCD100
movwf LBCD ;store 0 to LBCD
;read from to port b to binary
;port reading
clrw ;clear accumulator
TRIS PORTA ;Set port A as output
movlw 0x0 ;move literal value to accumulator
movwf PORTA ;move acuumaltor to port A
movlw 0xff ;move literal value to accumulator
TRIS PORTB ;Set port B as input
movf PORTB,0 ;move port B b to accumulator
movwf BINARY ;move accumulator to multiplicand
movlw 0x64 ;move literal value to accumulator
movwf POWER ;move 64 to POWER
borrowp
movf BINARY,0 ;move binary to accumulator
movwf DBINARY ;move binary to dummy binary
movf POWER,0 ;move power to accumulator
subwf BINARY,1 ;subtract accumulator from Binary,and the result is stored in BINARY register
btfss STATUS,0 ;skip next statement if CY=0
goto borrown
incf LBCD,1 ;increment BCD100
goto borrowp ;goto the next sequence
borrown
movf DBINARY,0 ;move dummy binary to accumulator
movwf BINARY ;move dummy binary to binary
movf LBCD,0 ;Local BCD to accumulator
movlw 0x64 ;move literal value to accumulator
subwf POWER,0 ;subtract 64 from power
btfsc STATUS,2 ;skip if clear,skip if z =0,output is not zero
call power64
btfsc STATUS,2 ;skip if clear,skip if z =0,output is not zero
goto borrowp
;if power is 0xa
movf LBCD,0 ;Local BCD to accumulator
movwf BCD10 ;move Local BCD to BCD 10
movf BINARY,0 ;move binary to accumulator
movwf BCD1 ;move binary to BCD
;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
;display of DIG0
movf BCD1,0 ;move BCD1 to 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
movf BCD10,0 ;move BCD10 to accumulator
movwf dig1 ;move accumulator to 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
;second digit
movf BCD100,0 ;move BCD100 to 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
clrw ;clear accumulator
movwf dig3 ;move accumulator to dig3
;check digit is grater 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
repeat goto repeat
power64
movf LBCD,0 ;Local BCD to accumulator
movwf BCD100 ;move Local BCD to BCD 100
clrw ;clear accumulator
movwf LBCD ;move accumulator to LBCD
movlw 0xa ;move literal value to accumulator
movwf POWER ;move accumulator to POWER
return
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.