?? lpc2300.s
字號(hào):
;// <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 0x00000007
CCLKCFG_Val EQU 0x00000003
USBCLKCFG_Val EQU 0x00000003
PCLKSEL0_Val EQU 0x00000000
PCLKSEL1_Val EQU 0x01000000
; 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
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