Lpc2000

Jaya,

Thanks for your concern, but my mind is perfectly clear.

At the risk of tiring you further, see my answers to your questions 
below.

--- In lpc2000@yahoogroups.com, Jayasooriah <jayasooriah@...> wrote:

> Try explaining what "The VIC does not handle interrupts that 
exhibit 
> transient behaviour" (direct quote from PL190 TRM) means.
> 

I guess it means what it says: it doesn't handle them. What it 
doesn't say is that the behaviour of the VIC is in any way undefined 
or unpredictable when they happen. It mightn't be the behaviour you 
want, but it is predictable and deterministic (unless you or ARM have 
evidence to the contrary, that is).

> The TRM does say is that when an interrupt exhibits transient 
behaviour, 
> "the priority logic of VIC is not set".  What does "not set" means?
> 
> Set to 0?  1?  ... 15? 16?

It doesn't matter what the priority is set to, as the solution 
doesn't make use of the priority in any way. 

> 
> Is the state of the priority logic defined after such an event?
> 

I'm sure it is, and that ARM and Philips know what it will be. The 
fact they have chosen not to document it doesn't mean it's undefined: 
simply that you shouldn't assume anything about it. That's OK though, 
as the solution I'm using doesn't.

> Who defines the behaviour of the VIC when it is subject to 
interrupts that 
> exhibit transient behaviour?

It's behaviour is governed by its internal design. Philips have 
documented how it behaves when the relevant conditions arise. The 
solution I use makes use of this information, together with all the 
other information available from both Philips and ARM.

> 
> Can I define it based on the result of my experiments?  Can you?
> 

Experiments can't define how it behaves (which is determined by its 
design), thay can only confirm that it behaves the way it does. My 
system and your experiments both confirm the behaviour as documented 
by Philips.

> I am happy to rephrase what I said thus: "I am not able to define 
what 
> happens in your system when you do the things you said you are 
doing" if 
> this will put an end to this saga.

I'm not asking you to define how it behaves, only to back an 
assertion you continue to make that the solution won't work.

All the evidence is that the system is entirely predictable and 
deterministic. Given there's no evidence to the contrary, my 
conclusion is that the solution is sound.

> 
> One more thing.  My questions above are for you to silently answer 
in your 
> own mind, in a hope that this would help you understand.  It is not 
my 
> intention for you to respond to my post and answer these questions.
> 

I've no problem in understanding what the issue is: my reason for 
answering is to help you understand.

> A very tired-of-Brendan Jaya
> 

Looks like we're both tired!

Best wishes
Brendan