NUC977 >> Assembly

Enhance Timer2 Controller(ETMR2)


參考資訊:
1. pdf
2. NUC970_NonOS_BSP

Timer Interrupt


ETMR_EN、MODE_SEL


Compare


Interrupt Enable


Interrupt Flag


main.s

  .equ GPIOD_DIR,     (0xb8003000 + 0xc0)
  .equ GPIOD_DATAOUT, (0xb8003000 + 0xc4)
  .equ CLK_PCLKEN0,   (0xb0000200 + 0x18)
  .equ AIC_MECRH,     (0xb8002000 + 0x134)
  .equ AIC_EOSCR,     (0xb8002000 + 0x150)
  .equ ETMR2_CTL,     (0xb8001600 + 0x00)
  .equ ETMR2_CMPR,    (0xb8001600 + 0x08)
  .equ ETMR2_IER,     (0xb8001600 + 0x0c)
  .equ ETMR2_ISR,     (0xb8001600 + 0x10)

  .data
blink: .dcb 1
  
  .text
  .align 2
  .global _start
_start:    b reset
_undef:    b .
_swi:      b .
_pabort:   b .
_dabort:   b .
_reserved: b .
_irq:      b irq_handler
_fiq:      b .
 
reset:
  mrs r0, cpsr
  bic r0, #0x80
  msr cpsr_c, r0

  ldr r0, =AIC_MECRH
  ldr r1, =(1 << 17)
  str r1, [r0]
 
  ldr r0, =CLK_PCLKEN0
  ldr r1, [r0]
  ldr r2, =((1 << 3) | (1 << 6))
  orr r1, r2
  str r1, [r0]

  ldr r0, =ETMR2_CMPR
  ldr r1, =6000000
  str r1, [r0]

  ldr r0, =ETMR2_CTL
  ldr r1, =1
  str r1, [r0]

  ldr r0, =ETMR2_IER
  ldr r1, =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 r0, =blink
  ldr r1, =0x00
  str r1, [r0]
  b .

irq_handler:
  ldr r0, =blink
  ldr r1, [r0]
  cmp r1, #0x00
  beq 1f
  ldr r0, =GPIOD_DATAOUT
  ldr r1, =(1 << 6)
  str r1, [r0]
  b 2f
1:
  ldr r0, =GPIOD_DATAOUT
  ldr r1, =~(1 << 6)
  str r1, [r0]
2:
  ldr r0, =blink
  ldr r1, [r0]
  eor r1, #0xff
  str r1, [r0]
 
  ldr r0, =AIC_EOSCR
  ldr r1, =1
  str r1, [r0]
 
  ldr r0, =ETMR2_ISR
  ldr r1, [r0]
  orr r1, #1
  str r1, [r0]
   
  ldr r0, =ETMR2_CTL
  ldr r1, =1
  str r1, [r0]
  
  subs pc, lr, #4
  .end

完成


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