Strange PC value at reset/startup

Hello Everyone,

I am just starting with a new board, a landboard with a nxp LPC1768.

I do not understand why i go in debug mode the starting point of my PC is 0x1fff0080

I use the startup given in keil 4 lite. This address is not random. In fact when I'm also trying with different example,

written in c, the starting point is the main of the c file, but if i hit the reset button, again the starting point is that address.

this is the disassembly but i cannot find nothing on the startup that redirect to that address.

0x1FFF007A 0000      MOVS     r0,r0
0x1FFF007C 0000      MOVS     r0,r0
0x1FFF007E 0000      MOVS     r0,r0
0x1FFF0080 F8DF4018  LDR.W    r4,[pc,#24]  ; @0x1FFF009C
0x1FFF0084 F8DF5010  LDR.W    r5,[pc,#16]  ; @0x1FFF0098
0x1FFF0088 6826      LDR      r6,[r4,#0x00]
0x1FFF008A EA050606  AND      r6,r5,r6
0x1FFF008E 6026      STR      r6,[r4,#0x00]
0x1FFF0090 F8DFF000  LDR.W    pc,[pc,#0]  ; @0x1FFF0094
0x1FFF0094 0201      LSLS     r1,r0,#8
0x1FFF0096 1FFF      SUBS     r7,r7,#7
0x1FFF0098 BFFF      ITTTT    
0x1FFF009A FFFFC3C0  DCD      0xC3C0FFFF
0x1FFF009E 400F      ANDS     r7,r7,r1
0x1FFF00A0 0000      MOVS     r0,r0
0x1FFF00A2 0000      MOVS     r0,r0

When i debug in simulation mode instead, the starting point is the reset Handles...

                PRESERVE8
                THUMB


; Vector Table Mapped to Address 0 at Reset

                AREA    RESET, DATA, READONLY
                EXPORT  __Vectors

__Vectors       DCD     __initial_sp              ; Top of Stack
                DCD     Reset_Handler             ; Reset Handler
                
                .....
                


                IF      :LNOT::DEF:NO_CRP
                AREA    |.ARM.__at_0x02FC|, CODE, READONLY
CRP_Key         DCD     0xFFFFFFFF
                ENDIF


                AREA    |.text|, CODE, READONLY


; Reset Handler

Reset_Handler   PROC
              
              
                my code
              
                ENDP

                
                

Can you please help me to understand what i'm wrong?

Thank you

Parents
  • Sorry you did not see a response on this. The Reset_Handler is indeed where execution begins, and can be thought of as the low-level entry point. This will ultimately call __main, the C library init code, which eventually calls main(), the standard start of the code from a C perspective.

    The debugger allows you to skip through this code (you may not wish to consider what is happening therein), with the 'run to main()' check box in the debugger configuration.

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  • Sorry you did not see a response on this. The Reset_Handler is indeed where execution begins, and can be thought of as the low-level entry point. This will ultimately call __main, the C library init code, which eventually calls main(), the standard start of the code from a C perspective.

    The debugger allows you to skip through this code (you may not wish to consider what is happening therein), with the 'run to main()' check box in the debugger configuration.

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