lpc2300.s

keil LPC 2300 web application source code.

;//                     <3=> Pclk = Cclk / 8
;//     <o7.16..17>  PCLK_UART2: Peripheral Clock Selection for UART2
;//                     <0=> Pclk = Cclk / 4
;//                     <1=> Pclk = Cclk
;//                     <2=> Pclk = Cclk / 2
;//                     <3=> Pclk = Cclk / 8
;//     <o7.18..19>  PCLK_UART3: Peripheral Clock Selection for UART3
;//                     <0=> Pclk = Cclk / 4
;//                     <1=> Pclk = Cclk
;//                     <2=> Pclk = Cclk / 2
;//                     <3=> Pclk = Cclk / 8
;//     <o7.20..21>   PCLK_I2C2: Peripheral Clock Selection for I2C2
;//                     <0=> Pclk = Cclk / 4
;//                     <1=> Pclk = Cclk
;//                     <2=> Pclk = Cclk / 2
;//                     <3=> Pclk = Cclk / 8
;//     <o7.22..23>    PCLK_I2S: Peripheral Clock Selection for I2S
;//                     <0=> Pclk = Cclk / 4
;//                     <1=> Pclk = Cclk
;//                     <2=> Pclk = Cclk / 2
;//                     <3=> Pclk = Cclk / 8
;//     <o7.24..25>    PCLK_MCI: Peripheral Clock Selection for MCI
;//                     <0=> Pclk = Cclk / 4
;//                     <1=> Pclk = Cclk
;//                     <2=> Pclk = Cclk / 2
;//                     <3=> Pclk = Cclk / 8
;//     <o7.28..29> PCLK_SYSCON: Peripheral Clock Selection for System Control Block
;//                     <0=> Pclk = Cclk / 4
;//                     <1=> Pclk = Cclk
;//                     <2=> Pclk = Cclk / 2
;//                     <3=> Pclk = Cclk / 8
;//   </h>
;// </e>
CLOCK_SETUP     EQU     1
SCS_Val         EQU     0x00000020
CLKSRCSEL_Val   EQU     0x00000001
PLLCFG_Val      EQU     0x0000000B
CCLKCFG_Val     EQU     0x00000004
USBCLKCFG_Val   EQU     0x00000005
PCLKSEL0_Val    EQU     0x00000000
PCLKSEL1_Val    EQU     0x00000000


; Memory Accelerator Module (MAM) definitions
MAM_BASE        EQU     0xE01FC000      ; MAM Base Address
MAMCR_OFS       EQU     0x00            ; MAM Control Offset
MAMTIM_OFS      EQU     0x04            ; MAM Timing Offset

;// <e> MAM Setup
;//   <o1.0..1>   MAM Control
;//               <0=> Disabled
;//               <1=> Partially Enabled
;//               <2=> Fully Enabled
;//               <i> Mode
;//   <o2.0..2>   MAM Timing
;//               <0=> Reserved  <1=> 1   <2=> 2   <3=> 3
;//               <4=> 4         <5=> 5   <6=> 6   <7=> 7
;//               <i> Fetch Cycles
;// </e>
MAM_SETUP       EQU     1
MAMCR_Val       EQU     0x00000002
MAMTIM_Val      EQU     0x00000004


; Area Definition and Entry Point
;  Startup Code must be linked first at Address at which it expects to run.

                AREA    RESET, CODE, READONLY
                ARM


; Exception Vectors
;  Mapped to Address 0.
;  Absolute addressing mode must be used.
;  Dummy Handlers are implemented as infinite loops which can be modified.

Vectors         LDR     PC, Reset_Addr         
                LDR     PC, Undef_Addr
                LDR     PC, SWI_Addr
                LDR     PC, PAbt_Addr
                LDR     PC, DAbt_Addr
                NOP                            ; Reserved Vector 
;               LDR     PC, IRQ_Addr
                LDR     PC, [PC, #-0x0120]     ; Vector from VicVectAddr
                LDR     PC, FIQ_Addr

Reset_Addr      DCD     Reset_Handler
Undef_Addr      DCD     Undef_Handler
SWI_Addr        DCD     SWI_Handler
PAbt_Addr       DCD     PAbt_Handler
DAbt_Addr       DCD     DAbt_Handler
                DCD     0                      ; Reserved Address 
IRQ_Addr        DCD     IRQ_Handler
FIQ_Addr        DCD     FIQ_Handler

Undef_Handler   B       Undef_Handler
SWI_Handler     B       SWI_Handler
PAbt_Handler    B       PAbt_Handler
DAbt_Handler    B       DAbt_Handler
IRQ_Handler     B       IRQ_Handler
FIQ_Handler     B       FIQ_Handler


; Reset Handler

                EXPORT  Reset_Handler
Reset_Handler   


; Setup Clock
                IF      CLOCK_SETUP != 0
                LDR     R0, =SCB_BASE
                MOV     R1, #0xAA
                MOV     R2, #0x55

;  Configure and Enable PLL
                LDR     R3, =SCS_Val          ; Enable main oscillator
                STR     R3, [R0, #SCS_OFS] 

                IF      (SCS_Val:AND:OSCEN) != 0  
OSC_Loop        LDR     R3, [R0, #SCS_OFS]    ; Wait for main osc stabilize
                ANDS    R3, R3, #OSCSTAT
                BEQ     OSC_Loop
                ENDIF

                LDR     R3, =CLKSRCSEL_Val    ; Select PLL source clock
                STR     R3, [R0, #CLKSRCSEL_OFS] 
                LDR     R3, =PLLCFG_Val
                STR     R3, [R0, #PLLCFG_OFS] 
                STR     R1, [R0, #PLLFEED_OFS]
                STR     R2, [R0, #PLLFEED_OFS]
                MOV     R3, #PLLCON_PLLE
                STR     R3, [R0, #PLLCON_OFS]
                STR     R1, [R0, #PLLFEED_OFS]
                STR     R2, [R0, #PLLFEED_OFS]

;  Wait until PLL Locked
PLL_Loop        LDR     R3, [R0, #PLLSTAT_OFS]
                ANDS    R3, R3, #PLLSTAT_PLOCK
                BEQ     PLL_Loop

M_N_Lock        LDR     R3, [R0, #PLLSTAT_OFS]
                LDR     R4, =(PLLSTAT_M:OR:PLLSTAT_N)
                AND     R3, R3, R4
                LDR     R4, =PLLCFG_Val
                EORS    R3, R3, R4
                BNE     M_N_Lock

;  Setup CPU clock divider
                MOV     R3, #CCLKCFG_Val
                STR     R3, [R0, #CCLKCFG_OFS]

;  Setup USB clock divider
                LDR     R3, =USBCLKCFG_Val
                STR     R3, [R0, #USBCLKCFG_OFS]

;  Setup Peripheral Clock
                LDR     R3, =PCLKSEL0_Val
                STR     R3, [R0, #PCLKSEL0_OFS]
                LDR     R3, =PCLKSEL1_Val
                STR     R3, [R0, #PCLKSEL1_OFS]

;  Switch to PLL Clock
                MOV     R3, #(PLLCON_PLLE:OR:PLLCON_PLLC)
                STR     R3, [R0, #PLLCON_OFS]
                STR     R1, [R0, #PLLFEED_OFS]
                STR     R2, [R0, #PLLFEED_OFS]
                ENDIF   ; CLOCK_SETUP


; Setup MAM
                IF      MAM_SETUP != 0
                LDR     R0, =MAM_BASE
                MOV     R1, #MAMTIM_Val
                STR     R1, [R0, #MAMTIM_OFS] 
                MOV     R1, #MAMCR_Val
                STR     R1, [R0, #MAMCR_OFS] 
                ENDIF   ; MAM_SETUP


; Memory Mapping (when Interrupt Vectors are in RAM)
MEMMAP          EQU     0xE01FC040      ; Memory Mapping Control
                IF      :DEF:REMAP
                LDR     R0, =MEMMAP
                IF      :DEF:RAM_MODE
                MOV     R1, #2
                ELSE
                MOV     R1, #1
                ENDIF
                STR     R1, [R0]
                ENDIF


; Initialise Interrupt System
;  ...


; Setup Stack for each mode

                LDR     R0, =Stack_Top

;  Enter Undefined Instruction Mode and set its Stack Pointer
                MSR     CPSR_c, #Mode_UND:OR:I_Bit:OR:F_Bit
                MOV     SP, R0
                SUB     R0, R0, #UND_Stack_Size

;  Enter Abort Mode and set its Stack Pointer
                MSR     CPSR_c, #Mode_ABT:OR:I_Bit:OR:F_Bit
                MOV     SP, R0
                SUB     R0, R0, #ABT_Stack_Size

;  Enter FIQ Mode and set its Stack Pointer
                MSR     CPSR_c, #Mode_FIQ:OR:I_Bit:OR:F_Bit
                MOV     SP, R0
                SUB     R0, R0, #FIQ_Stack_Size

;  Enter IRQ Mode and set its Stack Pointer
                MSR     CPSR_c, #Mode_IRQ:OR:I_Bit:OR:F_Bit
                MOV     SP, R0
                SUB     R0, R0, #IRQ_Stack_Size

;  Enter Supervisor Mode and set its Stack Pointer
                MSR     CPSR_c, #Mode_SVC:OR:I_Bit:OR:F_Bit
                MOV     SP, R0
                SUB     R0, R0, #SVC_Stack_Size

;  Enter User Mode and set its Stack Pointer
                MSR     CPSR_c, #Mode_USR
                MOV     SP, R0
                SUB     SL, SP, #USR_Stack_Size


; Enter the C code

                IMPORT  __main
                LDR     R0, =__main
                BX      R0


; User Initial Stack & Heap
                AREA    |.text|, CODE, READONLY

                IMPORT  __use_two_region_memory
                EXPORT  __user_initial_stackheap
__user_initial_stackheap

                LDR     R0, =  Heap_Mem
                LDR     R1, =(Stack_Mem + USR_Stack_Size)
                LDR     R2, = (Heap_Mem +      Heap_Size)
                LDR     R3, = Stack_Mem
                BX      LR


                END