Relocating program start position

Zvoc47 · Joined: 02 Apr 2015 Posts: 21

Is it somehow possible to relocate the program start? My debugging program works from 0x000000 to 0x007FFF and I'd like to have users upload programs from 0x008000 which means that their whole programs must start from there. This is my school and contest project as an alternative to the expensive JTAG that other students cannot afford. My debugging program should solve this problem.
About the interrupt vectors, I can handle that. All I have to do is put a JMP instruction after every vector to jump to +0x8000 of its address or I can use an interrupt trapper for debugging purposes. The user's vectors must be at 0x008000.

AVR-GCC can do that, but I'm not sure BASCOM AVR can. BASCOM had that function for 8051 and they disabled it. Is it possible to go around this limitation to somehow compile at 0x008000? Like tweaking the INC/REG files of the microcontroller.

(BASCOM-AVR version : 2.0.7.8 )

albertsm · Joined: 09 Apr 2004 Posts: 5921 Location: Holland

Yes B8051 supports this because the 8051 has a different architecture.
For AVR I could not find a reason to let code start from an address other than 0 or the boot address. You can only run code from flash, not from RAM, and since AVR had no boot vector selection either.....

you could do this :
$bootvector ' put int table into bootloader section so we can use interrupts
Config Intvectorselection = Enabled ' enabled means that the vector table points to the boot section
$loader=&H8000

I did not test it. As i understand it, you need the $romstart directive right?

Zvoc47 · Joined: 02 Apr 2015 Posts: 21

Yeah. User's program goes to 0x8000 while my program is 0x0000 and debugs the user's program.

albertsm · Joined: 09 Apr 2004 Posts: 5921 Location: Holland

if you write to support i can get you a version that supports $romstart. (dont know how quick but it seems simple)

Zvoc47 · Joined: 02 Apr 2015 Posts: 21

I sent the e-mail.