gec210 led bare metal development assembly instructions

Software environment: ADS1.2

Hardware platform: GEC210 development board

Running method: Use uboot to download to memory 0x30008000, then use the go command to run and view the effect.

The effect of this program is that all the LEDs are lit at the beginning, and then they change according to the binary addition until all the lights are off, and then the cycle repeats. The program will not return to uboot, it is an infinite loop

Schematic Description:

    The 4 LEDs are connected to the positive pole of the power supply through pull-up resistors, and the cathode of the LED is connected to the corresponding pins 0-3 of GPJ2io.

    So these 4 LEDs will light up when the CPU outputs a low level, and will go out when the CPU outputs a high level

    The program code is as follows:

    AREA init,code,readonly; Set segment attributes, code segment, code segment name inti, read-only attribute

    entry; entry, the same project should not have multiple entries

    ldr r0,=0xe0200280; led corresponding GPIO control register

    ldr r1,=0x1111 ;Configure as output mode

    str r1,[r0] ;Configure the corresponding pin to output mode

loop0    

    mov r1,#0x0

loop    

    strb r1,[r0,#4]

    add r1,r1,#1

    bl delay

    cmp r1,#0xf

    bne loop

    b loop0

    mov pc,lr; if the go command is used in uboot, it will jump back to uboot  

                              ;Not applicable to this program because the previous one is an infinite loop.

;The delay function is to let the CPU do something that has nothing to do with the LED, such as subtraction.

delay

    move r2, #0xff00000

delay1

    subs r2,r2,#1

    bne delay1

    mov pc,lr; until it decreases to 0, the delay function will return

    end

Note: If you use arm-linux-gcc to compile, pay attention to some differences in usage.