Timing issue

[viknes1985]

i wanted to read a pin's state.

1.

[Ttelmah]

Three different things here:

First, the internal input and output functions, whether for a bit, or a whole port byte, have two basically different modes of operation, according to whether FAST_IO is selected. If this is selected, then these functions operate _exactly the same_ as doing direct bit/byte I/O on the port. If not, extra instructions are added to automatically update the TRIS register. This latter is convenient, since it avoids TRIS errors (probably the commonest thing to get set wrong on a PIC), _but_ at a cost in speed.

Second, if FAST_IO is enabled, and you do a direct bit read or set, using:

[viknes1985]

thanks for the quick reply Ttelmah.

[viknes1985]

Hi Ttelmah,

I tried as you said, but the bit is always high.

Clarification :

I'm using int_rb to detect the changes in B4 (PIN_B4), so I used set_tris(0x10);

Basically I want to get the bit, which cause the interrupt.

If I never set tris, how do the PIC knows that I'm using B4 as input. Any suggestion?


Thanks in advance

[viknes1985]

Using interrupt coz alot of problem, using fast i/o solved the problem....

[Ttelmah]

A couple of comments.
First, you enable the global interrupt, but never enable INT_RB....

Then, you are clearing RBIF in the interrupt. This is a waste of time. The compiler already does this for you, unless you add the 'NOCLEAR' directive to the interrupt declaration.

Then, you don't declare FAST_IO, and you perform an output_low instruction, TRIS will be being updated for you. Do you want this?.

You are also using the flex LCD driver. What does this say about TRIS?. Would it support using fast_io?. Does it update TRIS?.

Best Wishes

[viknes1985]

Hi Ttelmah,

i'm using RBIE