掌機 - TRIMUI - Assembly - Button

參考資料：
http://nano.lichee.pro/
https://mangopi.org/mangopi_r

按鍵A是接到PD12


暫存器


提昇電阻


main.s

    .global _start

    .equiv GPIO_BASE,  0x01c20800 

    .equiv PD,         (0x24 * 3)
    .equiv PE,         (0x24 * 4)
    .equiv PORT_CFG0,  0x00
    .equiv PORT_CFG1,  0x04
    .equiv PORT_CFG2,  0x08
    .equiv PORT_DATA,  0x10
    .equiv PORT_PUL0,  0x1c

    .arm
    .text
_start:
    .long 0xea000016
    .byte 'e', 'G', 'O', 'N', '.', 'B', 'T', '0'
    .long 0, __spl_size
    .byte 'S', 'P', 'L', 2
    .long 0, 0
    .long 0, 0, 0, 0, 0, 0, 0, 0
    .long 0, 0, 0, 0, 0, 0, 0, 0

_vector:
    b reset
    b .
    b .
    b .
    b .
    b .
    b . 
    b .

reset:
    ldr r0, =GPIO_BASE
    ldr r1, =0x100000
    str r1, [r0, #(PE + PORT_CFG0)]
    ldr r1, =0x20
    str r1, [r0, #(PE + PORT_DATA)]

    ldr r1, =0x0000
    str r1, [r0, #(PD + PORT_CFG2)]
    ldr r1, =0x40
    str r1, [r0, #(PD + PORT_PUL0)]

0: 
    ldr r1, [r0, #(PD + PORT_DATA)]
    lsr r1, #14
    str r1, [r0, #(PE + PORT_DATA)]
    b 0b
    .end

完成