What kind of I/O do you want?
If it's simple I/O: PIC has many I/O pins witch are in groups called PORTs,
each PORT commonly have 8 I/O pins, eg PORTB.
First of all, you have to tell the PIC if the pin will be an input or a
output, so if you want that 18F452's pin 33 become an output pin, write in
assembly:
    BCF    TRISB,0
if you want to pin 34 be a input pin:
    BSF    TRISB,1
That is because TRISB is "input/output control" of PORTB, and "TRISB,0"
refers to RB0 pin and "TRISB,1" to RB1.

Finaly, to put a bit 1 or 0 in the output do that:
    BSF    PORTB,0    ; to make pin 33 = 5V or
    BCF    PORTB,0    ; to make pin 33 = 0V

To read a bit:
    MOVF    PORTB,W    ; so W register will receive the PORTB value.

Hope I could help, God bless you all,

Jonnathan Partamian




-------Mensagem original-------

De: pic microcontroller discussion list
Data: Sexta-feira, 07 de Margo de 2003 10:50:03
Para: PICLIST@MITVMA.MIT.EDU
Assunto: [PIC]: Need good tutorial on I/O

Could someone recommend a really good, basic tutorial for a beginner on
the in's and out's of doing I/O with a PIC? I found a really good one
by Jim Brown that covered a lot of stuff, but didn't get into the I/O.
(Preferably for the 18 series, but those seem to be few and far between
as yet)

Many thanks,
John

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