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Program: Read the Inputs and Turn them into Outputs, Toggle PORTC bit o. Write an assembly language program for the PIC18F4520 to read 4 most significant bits switch input on bits 7-4). For each switch that is in the "ON" or high position, compliment the inputs and output the bits to PORTB, least significant bits (PORTB bits 3-0) as outputs. Repeat the procedure every 500 msec. Simultaneously Togale bit o PORTC every1.5 seconds.

Using this method exactly but with the differences asked.

Answer 1

count_val EQU 0x03 :describe one variable with initial value as 3 START movlw OxFF make port A pins as imput movwf TRISA movlw0x00 :make port B pins as output movwf TRISB movwf TRIC ;make port C pins as output clrfLA TB make initial value as low clrfLATC ;make initial pin value to zero movlw Ob00111010 movwf OSCCON Setup the timer same as done there ISR movfPORTA, 0, 0 read port A pin inputs with remain in W swap xorlw 0xOF capsize the lower 4-bits in VW movwfPORTB ;wite the LSB 4-bit values to port B pins dcfsnz count val reduce count value and skip next line if not zero bra port_c toggle jump to label name port c toggle bcf INTCON, TMROIF retfie fW, 0 ;swap the nibbles in W register port c toggle movfPORTC, 0, 0 ;read port C xorlw 0x01 :toggle bit 0 movfPORTC write back to port C bra port_c toggle jump to label name port c toggle bcf INTCON, TMROIF movlw 0x03 W 3 movwf count val ;load counter with value 3 retfie end