微處理器 - Nuvoton NUC972 - Assembly - Watchdog Timer(WDT)

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

WDT_S


解鎖順序：0x59、0x16、0x88


WDTEN、RSTEN不是Read Only


main.s

    .equ GPIOB_DIR,     (0xb8003000 + 0x40)
    .equ GPIOB_DATAOUT, (0xb8003000 + 0x44)
    .equ CLK_PCLKEN0,   (0xb0000200 + 0x18)
    .equ WDT_CTL,       (0xb8001800 + 0x00)
    .equ WDT_ALTCTL,    (0xb8001800 + 0x04)
    .equ SYS_REGWPCTL,  (0xb0000000 + 0x1fc)
    .equ CLK_DIVCTL8,   (0xb0000200 + 0x40)

    .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 << 0))
    str r1, [r0]
    
    ldr r0, =CLK_DIVCTL8
    ldr r1, [r0]
    and r1, #0xffffffcf
    orr r1, #0x00000020
    str r1, [r0]
 
    ldr r0, =SYS_REGWPCTL
    ldr r1, =0x59
    ldr r2, =0x16
    ldr r3, =0x88
    str r1, [r0]
    str r2, [r0]
    str r3, [r0]
 
    ldr r0, =WDT_CTL
    ldr r1, =0x78f
    str r1, [r0]
     
    ldr r0, =GPIOB_DIR
    ldr r1, =(1 << 0)
    str r1, [r0]
loop:
    ldr r0, =GPIOB_DATAOUT
    ldr r1, =(1 << 0)
    str r1, [r0]
    ldr r4, =100000
1:
    nop
    subs r4, r4, #1
    bne 1b
    ldr r0, =GPIOB_DATAOUT
    ldr r1, =~(1 << 0)
    str r1, [r0]
    ldr r4, =100000
1:
    nop
    subs r4, r4, #1
    bne 1b
    b loop
    .end

P.S. 除了詭異的SYS_PWRON，還需要注意PA.3(1 = WDT is ON after power-on)腳位的設定，司徒目前PA.3是懸空，建議接到VCC，正確使用WDT

Watchdog Reset後，SDRAM資料消失，LED不再閃爍