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I/O Port simulation

Percy Lee

I monitering my I/O port from Peripherials -> I/O-ports -> Port 0

But the value of P0 and Pins are always diferrent
That is very strange..

I use P0 as an LCD data bus.
I set the value of P0, When I want to display a character on LCD.

but Pins bits can't reflect the value of P0

So my LCD display can't work normally.

Does any one known what happens?

thank you..

Parents
  • 0 in reply to Percy Lee

    Actually, to be even MORE precise, the signal function should appear as follows:

    define char P0_copy

P0_copy = P0;

signal void pullup_p0 (void) {
while (1) {
  wwatch (D:0x80);
  PORT0 = (PORT0 | ~P0_copy) & P0;
  P0_copy = P0;
  }
}

pullup_p0 ();

    This handles the problem of setting an input port pin to a value of 0 and writing P0 with a 1. This signal makes the input bit stay at 0.

    Jon

Reply
  • 0 in reply to Percy Lee

    Actually, to be even MORE precise, the signal function should appear as follows:

    define char P0_copy

P0_copy = P0;

signal void pullup_p0 (void) {
while (1) {
  wwatch (D:0x80);
  PORT0 = (PORT0 | ~P0_copy) & P0;
  P0_copy = P0;
  }
}

pullup_p0 ();

    This handles the problem of setting an input port pin to a value of 0 and writing P0 with a 1. This signal makes the input bit stay at 0.

    Jon

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