16.2 PORTx - Data Register
PORTx is a bidirectional port and its corresponding data direction register is TRISx.
Reading the PORTx register reads the status of the pins, whereas writing to it will write to the PORT latch. All write operations are Read-Modify-Write operations. Therefore, a write to a port implies that the PORT pins are read, and this value is modified and then written to the PORT data latch (LATx). The PORT data latch LATx holds the output port data and contains the latest value of a LATx or PORTx write. The example below shows how to initialize PORTA.
Initializing PORTA in Assembly
; This code example illustrates initializing the PORTA register.
; The other ports are initialized in the same manner.
BANKSEL PORTA ;
CLRF PORTA ;Clear PORTA
BANKSEL LATA ;
CLRF LATA ;Clear Data Latch
BANKSEL ANSELA ;
CLRF ANSELA ;Enable digital drivers
BANKSEL TRISA ;
MOVLW B'00111000' ;Set RA[5:3] as inputs
MOVWF TRISA ;and set others as outputs
Initializing PORTA in C
// This code example illustrates initializing the PORTA register. // The other ports are initialized in the same manner. PORTA = 0x00; // Clear PORTA LATA = 0x00; // Clear Data Latch ANSELA = 0x00; // Enable digital drivers TRISA = 0x38; // Set RA[5:3] as inputs and set others as outputs