Re: MPC566 interrupt help!!!

Hi Rajesh,

I use a 555 and don't use codewarrior, but all the registers you 
speak about sound familiar.

When the PIT generates an interrupt, an external exception occurs, 
which causes the program counter to jump to an address offset of 
0x500.
If you only have one external exception then you could have a branch 
to a PIT exception handler as the instruction placed at address 
offset 0x500(your printing output function), and that 
would be pretty much it.
If you have muiltiple potentional external exceptions set up then 
the "branch to" instruction would branch to a more generic handler, 
which would check the state of the SIPEND and SIVEC registers and 
ascertain what the source (in your case the PIT) of the exception was 
and then call your printing output function from the generic handler.

You will also have to consider that the context is saved and restored 
correctly, perhaps this interrupt.c file offers some of that "for 
free"?. In addition, it is good practice to minimise the content of 
the ISR, by perhaps simply setting a software flag that is checked 
for later - it all depends on the application. Hope that helps a 
little.


--- In [email protected], "Rajesh" <rajesh86us@...> wrote:
>
> 
>  Dear Grp members,
>                    I am working on MPC566 EVB with Codewarior 
compiler. 
> At present I am trying to print an output at a particular interval. 
For 
> that, I am initiallizing the timer registers PISCR, PITC, PITR, in 
> which PITC is configured. I have written an ISR function(to print 
an 
> output), but since the exception handler will call my ISR function 
(on 
> interrupt request), where exactly I have to define this ISR in the 
> handler? While creating a project in codewarior, an 'interrupt.c' 
file 
> is automatically generated. What is the use of this file?
> Hope I am able to define my problem. Any kind of help is 
appreciated. 
> 
> -regards
> Rajesh
>







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