Input-Output Operations

Input/Output Operations:

• Each PIC microprocessor has number of ports number from port A, to port L, depends on how many pins exists in this microprocessor.
• Each port has 3 special registers associated with it: PORTx, TRISx, and LATx.
• TRISx is the register which responsible to set the port as input port or output port. Setting TRISx bits to zeros would make portx to be an output port, and setting the TRISx bits to ones would make portx to be an input port.

Example1:
Assign value 66H to the output port C:
asm code

MOVLW	0x0
MOVWF	TRISC
 L1	MOVLW	0x66
	MOVWF	PORTC
	GOTO		L1

Example2:
Make port C as input port, add 12 to it and port B as output port B:
asm code

MOVLW	B’00000000’
	MOVWF	TRISB
	MOVLW	B’11111111’
	MOVWF	TRISC
L2	MOVF		PORTC, W
	ADDLW		12
	MOVWF	PORTB
	GOTO		L2