Forums

LPC2103 VIC Protection Register

Started by Alexander K. Carey February 15, 2006
Where's the Protection Register?????
  In reference to the users manual UM10161 by philips page 54 fig 13. block
diagram
  Rev 01. 11 Jan 2006.
  Looking at this block diagram I don't see just where this register comes into
play in-reguards to the VIC. I understand it is one bit wide, but what part of
the VIC does it affect??? Anybody Know!!
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An Engineer's Guide to the LPC2100 Series

Have a look at section 5.4.13 on page 52 of the same document.
Essentially this prevents accidental? sabotage of the VIC
by processes in User mode.
I don't know whether a user write to a VIC register is simply
ignored or if an exception occurs. That might be documented in
the Arm PrimeCell VIC documentation PL190 (link on page 44
of the UM).

Hope this helps,
Danish

--- In lpc2000@lpc2..., "Alexander K. Carey"
<alvingoesdown@...> wrote:
>
> Where's the Protection Register?????
>   In reference to the users manual UM10161 by philips page 54 fig
13. block diagram
>   Rev 01. 11 Jan 2006.
>   Looking at this block diagram I don't see just where this register
comes into play in-reguards to the VIC. I understand it is one bit
wide, but what part of the VIC does it affect??? Anybody Know!!
	
More correctly, it prevents "accidental overwrites".  It is easy
to forget 
that the fence between user and privileged modes of LPC is a convenience 
and does not prevent "sabotage".

--- In lpc2000@lpc2..., "Danish Ali" <danish@...> wrote:
 > Essentially this prevents accidental? sabotage of the VIC
 > by processes in User mode.

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Thanks for the info Danish,
  I have a copy of both docs I'll burn some midnight reading tonight.

Danish Ali <danish@dani...> wrote:
  Have a look at section 5.4.13 on page 52 of the same document.
Essentially this prevents accidental? sabotage of the VIC
by processes in User mode.
I don't know whether a user write to a VIC register is simply
ignored or if an exception occurs. That might be documented in
the Arm PrimeCell VIC documentation PL190 (link on page 44
of the UM).

Hope this helps,
Danish

--- In lpc2000@lpc2..., "Alexander K. Carey"
<alvingoesdown@...> wrote:
>
> Where's the Protection Register?????
>   In reference to the users manual UM10161 by philips page 54 fig
13. block diagram
>   Rev 01. 11 Jan 2006.
>   Looking at this block diagram I don't see just where this register
comes into play in-reguards to the VIC. I understand it is one bit
wide, but what part of the VIC does it affect??? Anybody Know!!
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