微處理器 - NXP LPC2103 - Assembly - UART

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 U0LCR,   0xe000c00c
    .equ U0DLL,   0xe000c000
    .equ U0DLM,   0xe000c004
    .equ U0THR,   0xe000c000

    .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, =PINSEL0
    ldr r1, =0x05
    str r1, [r0]

    ldr r0, =U0LCR
    ldr r1, =0x83
    str r1, [r0]

    /* 9600bps */
    /* 12000000 / 16 / 4 / 9600 = 0x13 */
    ldr r0, =U0DLM
    ldr r1, =0x00
    str r1, [r0]

    ldr r0, =U0DLL
    ldr r1, =0x13
    str r1, [r0]

    ldr r0, =U0LCR
    ldr r1, =0x03
    str r1, [r0]

loop:
    ldr r4, =50000
1:
    nop
    subs r4, r4, #1
    bne 1b
    ldr r0, =U0THR
    ldr r1, =0x55
    str r1, [r0]
    b loop
    .end

完成