68300

Hi All Y'All,

In trying to track down a niggly bug on my '332, I came across a
question...

You typically have to acknowledge an interrupt somehow, by clearing a
bit or reading a register. How do you acknowledge the PIT (Periodic
Interrupt Timer in the SIM) interrupt?

Thanks,
Andrei

At 11:11 PM 3/12/2007, andreichichak wrote:

>You typically have to acknowledge an interrupt somehow, by clearing a
>bit or reading a register. How do you acknowledge the PIT (Periodic
>Interrupt Timer in the SIM) interrupt?

My code doesn't.  Checked the SIM book and the SIM section in the 
'360 book; neither mentions any ack requirement.


-- 
newell  N5TNL

Thanks Scott,

I thought it was rather odd that it doesn't need an ack.

Have all of the Freescale people left the building?

Andrei

> 
> My code doesn't.  Checked the SIM book and the SIM section in the 
> '360 book; neither mentions any ack requirement.
> 
> 
> -- 
> newell  N5TNL
>

PIT just does it thing! 

SXSW (south by southwest) Festival this week, as is Spring Break in the 
Austin,TX
area.  http://2007.sxsw.com/

Where's Charlie (Melear)?  Haven't heard from him in ages.

Tom Walter

----- Original Message -----
From: andreichichak <groups@...>
Date: Wednesday, March 14, 2007 12:00 pm

Subject: [68300] Re: Proper way to acknowledge a PIT interrupt
To: 68300@yahoogroups.com

> Thanks Scott,
> 
> I thought it was rather odd that it doesn't need an ack.
> 
> Have all of the Freescale people left the building?
> 
> Andrei
> 
> > 
> > My code doesn't.  Checked the SIM book and the SIM section in 
> the 
> > '360 book; neither mentions any ack requirement.
> > 
> > 
> > -- 
> > newell  N5TNL
> >
> 
> 
>

Andrei,

Did you find the bug yet?  If not have you seen the errata about having an 
external device using the same interrupt level as the PIT?  Could that be 
your problem?

(Sorry I don't have a reference for you.)

Jeff




"andreichichak" <groups@...> 
Sent by: 68300@yahoogroups.com
03/12/2007 09:11 PM
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Subject
[68300] Proper way to acknowledge a PIT interrupt






Hi All Y'All,

In trying to track down a niggly bug on my '332, I came across a
question...

You typically have to acknowledge an interrupt somehow, by clearing a
bit or reading a register. How do you acknowledge the PIT (Periodic
Interrupt Timer in the SIM) interrupt?

Thanks,
Andrei

 


[Non-text portions of this message have been removed]

Hi Jeff (and everybody else)

>Andrei,
>
>Did you find the bug yet?

No, I didn't.

The possible issue with the PIT interrupt seems to have been teaser. 
As we have seen from the various responses, it does not seem like you 
have to do anything to acknowledge the PIT.

The problem that I was trying to track down was actually with the 
TPU. When using the UART function, I would occasionally see a 
doubling of the input characters and a mass retransmission of my 
output buffers by my interrupt routines. After much head scratching 
and searching I deduced that the interrupt routines were occasionally 
triggered twice for a single event (I was getting two interrupts for 
a single transmitter empty event, and two interrupts for a single 
character received event). I really didn't expect to see an issue as 
I only had 12 half UARTs running at 300 baud, one half UART running 
at 9600 baud, two DIOs, and one PWM that was turned off.

I had never seen anything like this before, but I am using a new 
compiler (GCC), and running at 4MHz instead of 16MHz, so the low 
level routines for my OS (uC/OS-II) had to be reworked.

I eventually ran across an app note for the TPU UART that mentioned 
the position of the interrupt clear instructions with respect to the 
accessing of the data buffers, and how you CAN get doubling of interrupts.

After much head scratching and experimentation, I bolstered other 
pieces of the system to be able to detect and throw away packets that 
have the corrupted data.

>If not have you seen the errata about having an
>external device using the same interrupt level as the PIT? Could that be
>your problem?

No, I don't think so. I'll look for the errata sheet though. I'm not 
using any external interrupts and the PIT is the only device assigned 
to its interrupt level.

>(Sorry I don't have a reference for you.)
>
>Jeff

Thanks for your help,

Andrei