Lpc2000

Thanks for the answer. Actually I'm not intentionally setting a reserved bit 
to one. I just want to use bitfields in C. I cant now as the generated code 
only deals with the bits accessed (naturally). So I have to use 
read-modify-mask off reserved-write type of instructions. This way I cant 
take advantage of bitfields which makes life a bit easier. More code is 
another disadvantage.
If we new that this limitation is due to future compatibility concerns, then 
it would be nice to use bitfields.

kerem


----- Original Message ----- 
From: "Lewin A.R.W. Edwards" <larwe@...>
To: <lpc2000@yahoogroups.com>
Sent: Monday, December 20, 2004 4:40 PM
Subject: Re: [lpc2000] reserved bits of LPC2214


>
>
>> The user manual of LPC2214 states that a reserved bit should not be
>> set to 1. Is it because of future compatibility issues or is it a
>> hardware requirement?, i.e., what if we set a reserved bit to 1.
>> will the IC burn or present undefined behaviour?
>
> If you need to ask this question, you're living too close to the
> bleeding edge. Undefined bits might, if set:
>
> 1. do nothing
> 2. do nothing on current masks, but do something spectacularly strange
> on a future mask
> 3. activate an internal test mode feature that fries your external
> hardware by activating "impossible" combinations of I/Os
>
> I'm not surprised you didn't get an answer. The behavior is undefined.
> You would get exactly the same (non-) answer if you asked "How safe is
> it to run the chip twenty degrees above its absolute maximum rating?"
>
> -- 
> Lewin A.R.W. Edwards
> Consulting - http://www.zws.com/
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