微處理器 - Nuvoton NUC977 - Assembly - Windowed Watchdog Timer(WWDT)

參考資訊：
https://github.com/OpenNuvoton/NUC970_NonOS_BSP

WWDTEN、PSCSEL


main.s

    .equ GPIOD_DIR,     (0xb8003000 + 0xc0)
    .equ GPIOD_DATAOUT, (0xb8003000 + 0xc4)
    .equ CLK_PCLKEN0,   (0xb0000200 + 0x18)
    .equ WWDT_RLDCNT,   (0xb8001900 + 0x00)
    .equ WWDT_CTL,      (0xb8001900 + 0x04)
    .equ WWDT_STATUS,   (0xb8001900 + 0x08)

    .text
    .align 2
    .global _start
_start:    b reset
_undef:    b .
_swi:      b .
_pabort:   b .
_dabort:   b .
_reserved: b .
_irq:      b .
_fiq:      b .
 
reset:
    ldr r0, =CLK_PCLKEN0
    ldr r1, [r0]
    orr r1, #((1 << 3) | (1 << 1))
    str r1, [r0]

    ldr r0, =GPIOD_DIR
    ldr r1, =(1 << 6)
    str r1, [r0]

    ldr r0, =GPIOD_DATAOUT
    ldr r1, =~(1 << 6)
    str r1, [r0]

    ldr r4, =1000000
1:
    nop
    subs r4, r4, #1
    bne 1b

    ldr r0, =WWDT_CTL
    ldr r1, =0xf01
    str r1, [r0]
    b .
    .end

若沒有在限定的Window期間Reset Watchdog，則觸發系統Reset，SDRAM資料消失，LED熄滅