微處理器 - NXP LPC2103 - Assembly - EINT1(Non-vectored IRQ)

參考資料：
https://www.keil.com/dd/docs/datashts/philips/user_manual_lpc2101_2102_2103.pdf

暫存器




main.s

    .equ IODIR,          0xe0028008
    .equ IOCLR,          0xe002800c
    .equ IOSET,          0xe0028004
    .equ PINSEL0,        0xe002c000
    .equ EXTINT,         0xe01fc140
    .equ VICIntEnable,   0xfffff010
    .equ VICDefVectAddr, 0xfffff034
    .equ VICVectAddr0,   0xfffff100
    .equ VICVectCntl0,   0xfffff200

    .text
    .align 2
    .global _start
_start:    b reset
_undef:    b .
_swi:      b .
_pabort:   b .
_dabort:   b .
_reserved: b .
_irq:      ldr pc, [pc, #-0xff0]
_fiq:      b .
   
reset:
    mrs r0, cpsr
    bic r0, #0x80
    msr cpsr_c, r0

    ldr r0, =PINSEL0
    ldr r1, =(1 << 28)
    str r1, [r0]

    ldr r0, =VICIntEnable
    ldr r1, =(1 << 15)
    str r1, [r0]

    ldr r0, =VICDefVectAddr
    ldr r1, =irq_handler
    str r1, [r0]

    ldr r0, =VICVectCntl0
    ldr r1, =0x0f
    str r1, [r0]

    ldr r0, =IODIR
    ldr r1, =(1 << 22)
    str r1, [r0]

    ldr r0, =IOCLR
    ldr r1, =(1 << 22)
    str r1, [r0]
    b .

irq_handler:
    ldr r0, =IOSET
    ldr r1, =(1 << 22)
    str r1, [r0]
    ldr r0, =EXTINT
    ldr r1, =0x02
    str r1, [r0]
    subs pc, lr, #4
    .end

P.S. ldr pc, [pc, #-0xff0] = 0x18(irq address) + 8(fetch、decode) - 0xff0 = VICVectAddr(0xfffff030)

完成