I am trying few things on beaglebone black. I want to do ARM assembly programming on this board without using Linux. So i pressed SW2 on the board while powering it so it skips the internal booting and waits for SD card which i haven't inserted. This way i tried to avoid booting Uboot. I also created empty project using code composer studio v5.5 and following is the code that i used in the file main_code.S
.text .global _main .code 32 _main: movs r0,#500 ldr r1,=0x44E0713c strt r0,[r1] loop: adds r1,r0 subs r0,#1 bne loop deadloop: b deadloop .end
Now i also have debugger BlackHawk USB 100v2 and have selected same in project properties. when i debug this after successful build, it is in supervisor mode at start. when i do step by step debug it moves to abort mode after "strt r0,[r1]" where r1 holds the address of GPIO0 dataout register.
Also, I cannot see register values in the register tab for the same, it says "Error:Unable to read". Can anyone tell me why this happens. I would really appreciate if you could tell me way to access these memory locations to perform IO operations in assembly and without the Linux booting.