Lpc2000

--- In lpc2000@yahoogroups.com, "rockraj_2003" <rockraj_2003@y...> 
wrote:
> 
> Hello Charles,
> 
> Thank U!
> 
> I found another prob., but now the problem is to change to thumb 
mode.
> How to put the processor from ARM mode to THUMB mode by using ASM 
> COMMANDS.

The way to go from ARM to thumb mode is to use the bx instruction with 
the 0th bit set.

You can do this like:

     LDR     r0,=thumb_address
     ORR     r0,#1
     bx      r0

Normally though the assemblers and compilers will automatically append 
the 1 to thumb addresses so you only need to write:

     LDR     r0,=thumb_address
     bx      r0



> 
>     LDR          R0, =0xE002C000
>     MOV          R1, #10
>     STR          R1, [R0, #0]
>     LDR          R0, =0xE001400C
>     MOV          R1, #0
>     STR          R1, [R0, #0]
> 
> Kindly explain me the STATEMENT 
> 
>     STR          R1, [R0, #0]

This will store the value in register R1 to the location stored in 
register R0 with an offset of zero.


This forum is not really the place to deal with this level of 
question. I suggest getting an ARM assembler manual.


> what it does.
> upto my knowledge i think it will store the value 0 to R0.
> 
> 
> Kindly exaplain me how to pu the processor in thumb mode.
> 
> with regds,
> Rajendra R
> 
> 
> --- In lpc2000@yahoogroups.com, Charles Manning <manningc2@a...> 
> wrote:
> > On Tuesday 29 March 2005 16:53, rockraj_2003 wrote:
> > > Hello Friends,
> > >
> > > I am using IAR EMBEDDED WORKBENCH.
> > > The code shown below is produced by the IAR compiler.
> > > I want to know what is the offset & how they are using the 
OFFSET 
> in
> > > PC.
> > >
> > > Can any one explain me the below program.
> > >
> > >
> > >  MEMMAP = 2;
> > >       LDR          R0, [PC,#0x354] [0x68C] =MEMMAP (0xE01FC040)
> > >       MOV          R1, #2
> > >       STRB         R1, [R0, #0]
> > >
> > >   PINSEL0  = 0x0000000A;
> > >  0x0000033C 48D4      LDR          R0, [PC,#0x350]; [0x690] 
> =PINSEL0
> > > (0xE002C000)
> > >  0x0000033E 210A      MOV          R1, #10
> > >  0x00000340 6001      STR          R1, [R0, #0]
> > >
> > >
> > > Explain me the LDR & how it points to this address.0xE01FC040
> > >
> > >       LDR          R0, [PC,#0x354] [0x68C] =MEMMAP (0xE01FC040)
> > 
> > This is using what is called a literal pool. The actual address is 
> not part 
> > of the instruction, but is stored.
> > 
> > When you write code like this you do it as follows:
> >    ldr r0, =0xE01FC040
> > 
> > The assembler then saves the value futrther on in the .text 
segment 
> and sets 
> > up an instruction to point to that using an offset relative to the 
> PC.
> > 
> > ie.
> > 
> >     ldr r0,[PC,#offset_to_where_value_is_stored]
> > 
> > value_stored_here:
> >           .word  0xE01FC040
> > 
> > 
> > 
> > 
> > 
> > 
> > >
> > > kindly help me,
> > >
> > > with regards,
> > > Rajendra R
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >