.section .init

.globl _start

_start:
    ldr r0,=0x20200000 //GPIO controller address

    mov r1, #1  // put 1 into r1
    lsl r1, #18 //logical shift left by 18
    str r1, [r0, #4] //store register

    loop:
        mov r1, #1
        lsl r1, #16 //set pin 16
        str r1, [r0, #40] // toggle GPIO on

        mov r2, #0x3f0000
    wait:
        sub r2, #1
        cmp r2, #0
        bne wait

    mov r1, #1
    lsl r1, #16 //set pin 16
    str r1, [r0, #28] // toggle GPIO ofrf

        mov r2, #0x3f0000
    wait2:
        sub r2, #1
        cmp r2, #0
        bne wait2
    b loop




