微處理器 - NXP MK20DX256 (Teensy 3.2) - Assembly - LED

參考資訊：
https://www.nxp.com/docs/en/data-sheet/K20P64M72SF1.pdf
https://www.nxp.com/docs/en/reference-manual/K20P64M72SF1RM.pdf
https://forum.pjrc.com/threads/25762-Turn-the-LED-on-with-assembler-code-(-Teensy-3-1-)?p=47739&viewfull=1#post47739

LED連接到PTC-5


Disable Watchdog


Port Clock


Enable Port


Port Direction


Port Output


main.s

    .equiv GPIOC_BASE,   0x400ff080
    .equiv GPIO_PDDR,    0x14
    .equiv GPIO_PDOR,    0x00

    .equiv SIM_BASE,     0x40047000
    .equiv SIM_SCGC5,    0x1038

    .equiv WDOG_BASE,    0x40052000
    .equiv WDOG_STCTRLH, 0x00
    .equiv WDOG_UNLOCK,  0x0e

    .equiv PORTC_BASE,   0x4004b000
    .equiv PORTC_PCR5,   0x14

    .thumb
    .cpu cortex-m4
    .syntax unified

    .global _start

    .text
    .org 0x0000
_start:
    .word 0x20008000
    .word reset
 
    .org 0x0100
    .thumb_func
reset:
    ldr r0, =WDOG_BASE
    ldr r1, =0xc520
    strh r1, [r0, #WDOG_UNLOCK]
    ldr r1, =0xd928
    strh r1, [r0, #WDOG_UNLOCK]
    ldr r1, =0x0000
    strh r1, [r0, #WDOG_STCTRLH]

    ldr r0, =SIM_BASE + SIM_SCGC5
    ldr r1, =(1 << 11)
    str r1, [r0]

    ldr r0, =PORTC_BASE
    ldr r1, =(1 << 8)
    str r1, [r0, #PORTC_PCR5]

    ldr r0, =GPIOC_BASE
    ldr r1, =(1 << 5)
    str r1, [r0, #GPIO_PDDR]

0:
    eor r1, #(1 << 5)
    str r1, [r0, #GPIO_PDOR]
    ldr r2, =1000000
1:
    subs r2, #1
    bne 1b
    b 0b
    .end

main.ld

MEMORY {
    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 512K
    SRAM (W!RX) : ORIGIN = 0x20000000, LENGTH = 64K
}

SECTIONS {
    .text   : { *(.text*) } > FLASH
    .rodata : { *(.rodata*) } > FLASH
    .bss    : { *(.bss*) } > FLASH
}

Makefile

all:
	arm-none-eabi-as -mcpu=cortex-m4 main.s -o main.o
	arm-none-eabi-ld -T main.ld -o main.elf main.o
	arm-none-eabi-objcopy -O ihex main.elf main.hex 

flash:
	sudo teensy_loader_cli --mcu=mk20dx256 -w main.hex

clean:
	rm -rf main.o main.elf main.hex

編譯、燒錄
1. 連接開發板至PC
2. 按一下燒錄按鍵
3. 執行如下命令

$ make
    arm-none-eabi-as -mcpu=cortex-m4 main.s -o main.o
    arm-none-eabi-ld -T main.ld -o main.elf main.o
    arm-none-eabi-objcopy -O ihex main.elf main.hex

$ make flash
    sudo teensy_loader_cli --mcu=mk20dx256 -w main.hex

完成