NUC977 >> Assembly

Windowed Watchdog Timer(WWDT)

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參考資訊：
1. pdf
2. 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

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