Lpc2000

--- In lpc2000@yahoogroups.com, Jayasooriah <jayasooriah@...> wrote:
>
> Hi Marko,
> 
> I read the AN a few times -- in section 3.1, in explaining one
source of 
> spurious interrupts when feeding watchdog timer, it says:

> 
> "The disabling of interrupts before the feed sequence may lead to the 
> occurrence of spurious interrupts."
> 
> OS'es disable and enable interrupts all the time.  
>They however do not have to deal with spurious interrupts as a
>consequence.  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Hi Jayasooriah,

Oh? 
On ARM core with PL 190 VIC, not dealing with this consequence is a
"blissful ignorance", IMHO.

>Interrupts can be lost 
> as a result due to folding, but spurious interrupts?  In the case of
LPC, 
> this AN suggests the OS must cope with spurious interrupts if it
disables 
> and enables interrupts.

Correct. 
Read this FAQ first: http://www.arm.com/support/faqip/3677.html
This is the original source. Philips included this info in their
latest LPC2148 UM, very helpful.
 
> This begs the question: is this erroneous behaviour LPC specific, or
does 
> it affect any other (all?) ARM VIC implementations?

ARM's VIC Prime Cell PL 190, see document "ARM DDI 0181C", and Errata
01.This document can be found on www.arm.com. 

LPC 2000 is an ARMv4T (ATM7) with VIC PL190. This mis-behavior is
specific to ARM7 core(according to ARM). 
There are other interrupt controllers for ARM7-based MCUs (Atmel,
Freescale, ST, etc.). I do not know how they address this
architectural flaw of spurious interrupts. I'd like to know.
 
> The AN suggests the latter is the case but I cannot find any
documentation 
> relating to ARM Primecell VIC specifications that supports this.
                                               ^^^^^^^^^^^^^^^^^^
What do you mean by "that supports this"?

After reading 'this': http://www.arm.com/support/faqip/3677.html,
'that' becomes clearer. 
;-)

Take care.

Roger

> 
> Jaya
> 
> --- In lpc2000@yahoogroups.com, "Marko Pavlin (home)" <mp@> wrote:
>  >
>  > Just a reference:
>  > 
>
http://www.standardics.philips.com/support/documents/microcontrollers/pdf/an10414.pdf
>  > 
> 
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