Bare-metal ATSAM3X8E (Arduino Due)

Toolchain: ST-LINK/V2 programmer, OpenOCD, ARM GNU Compiler Toolchain.

Wiring

Arduino Due

ATSAM3X8E boots into 0x00000, which is mapped to ROM. ROM contains the SAM-BA bootloader.

Remap start address to flash0 (flash driver section, OpenOCD manual AT91SAM3):

$ openocd -f openocd-due.cfg
$ telnet localhost 4444
  > halt
  > at91sam3 gpnvm show
  > at91sam3 gpnvm set 1
  > at91sam3 gpnvm show

Place the vector table at the start of flash0 and initialize the stack pointer to the top of the RAM:

MEMORY
{
    rom (rx)  : ORIGIN = 0x00080000, LENGTH = 512K
    ram (rwx) : ORIGIN = 0x20000000, LENGTH = 96K
}

SECTIONS
{
    .text :
    {
        KEEP(*(.vtor))  /* Vector table defined in main.c */
        *(.text*)
        *(.rodata*)
    } > rom

    /* Data, bss sections */
}

_sp = ORIGIN(ram) + LENGTH(ram); /* Descending stack */

Build and upload the program:

$ arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -T script.ld \
    -nostartfiles \
    -nostdlib \
    -o a.elf main.c
$ openocd -f openocd-due.cfg -c "program a.elf verify reset exit"

Commit: 3184969.