2006-02-18 by George M. Gallant, Jr.
Thanks Brendan.
I don't understand the documentation about switching modes.
During startup I cycle thru each mode and allocate a default
stack. After that I switch back to SVC mode. According to the
documentation this should fail as switching from SYS to SVC
can only occur as a result of an exception.
George
On Sat, 2006-02-18 at 06:13 +0000, brendanmurphy37 wrote:
>
> George,
>
> I don't know the answer to your specific question off-hand. However,
> I'm sure you'd find it helpful to get some documentation on ARM
> processors.
>
> One of the problems with micros that use standard (as opposed to
> proprietary) cores, such as ARM, is that the manufacturers tend not
> to repeat documentation that can be found elsewhere. This is a bit
> inconvenient.
>
> The best source for information you require is direct from ARM.
> Check out the ARM7TDMI Technical Reference Manual, which can be
> found at:
>
> http://www.arm.com/documentation/ARMProcessor_Cores/index.html
>
> This covers all the LPC2xxx series.
>
> The standard reference for ARM is the "ARM ARM" (real title: "ARM
> Technnical Reference Manual"). Unfortuntely, they expect you to pay
> for this. It's a really useful reference to have though. See:
>
> http://www.amazon.com/gp/product/0201737191/sr=8-
> 1/qid=1140242347/ref=pd_bbs_1/102-6410308-4751357?%5Fencoding=UTF8
>
> Hope this helps.
>
> Brendan
>
> --- In lpc2000@yahoogroups.com, "George M. Gallant, Jr."
> <ggallant571@...> wrote:
> >
> > Is it possible to load the SPSR in the lpc2214.
> >
> > For example:
> >
> > mov r0, #0xD0 ;set previous mode
> to user
> > msr spsr_cxsf, r0
> >
> > I do this at boot and then read and display CPSR & SPSR
> >
> > CPSR = 0x000000D3
> > SPSR = 0x800000D3
> >
> > George
> >
> > On Thu, 2006-02-16 at 18:47 +0000, brendanmurphy37 wrote:
> >
> > >
> > > The suffix to CPSR refers to which field(s) of the CPSR is
> > > rereferenced (you can specify one or more). Defined fields are:
> > >
> > > c - control
> > > f - flags
> > > s - status
> > > x - extension
> > >
> > > Thus., for example, you can update only those parts of the CPSR
> that
> > > are of interest. See a description of the CPSR for details.
> > >
> > > Brendan
> > >
> > > --- In lpc2000@yahoogroups.com, "George M. Gallant, Jr."
> > > <ggallant571@> wrote:
> > > >
> > > > I notice in many assembly language examples the use of CPSR_c
> > > > & CPSR_cxsf but donot understand the differences.
> > > >
> > > > Thanks,
> > > > George
> > > >
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > >
> > >
> > >
> > >
> > >
> > >
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