Custom Board and SAM-BA

--- In A..., "mjdistl" wrote:
> my custom board works fine on samba with sam7x256
> make sure you have a 1.5k pullup resistor to 3.3v and pin
> 3 on usb conn. power up your board with erase pin pulled
> high. power down remove erase jumper. power back up and
> when windows finds new hardware load the 6124sys driver
> from samba.

Thanks everyone. From your words I understand that SAM-BA should
definetly work with my custom board and double ( even triple ) check
my board and find the problem.

Thanks mjdistl. Your suggestion for the pull-up gave me a great help.

Best Ragards,
ar



Start a New Thread

Guys guys guys,

So close,... but not quite there.

I dunno about the 7S series chips, but here's how the 7X256 works for
us (and the 7XC256 as well) for us.

The SAMBA boot code is stored in ROM on the 7X(C)256's. The GPNVM bit
(is it 2?) selects whether the ROM (default - GPNVM 2 erased), or
Application FLASH (GPNVM 2 programmed), is mapped in at 0x0000000 on
bootup. I can't remember if the ROM is mapped up somewhere higher up
in memory as well (and is therefore "visible" after the remap
instruction), but I'd be surprised if it isn't.

Now, if your installed application code has a means whereby it can
alter the GPNVM bit, (eg. via a command/password to a command shell
running on the serial port or whatever), you can jump back to the SAMBA
bootloader by simply clearing the GPNVM bit and resetting the micro.
You can get back to your application by using the SAMBA windows client
to reprogram the GPNVM bit and reset the micro (again!).

Failing that, if the SAMBA rom is accessible, and written in entirely
relocatable code, then you could possibly get away with a programmed
jump to the address and boot into SAMBA that way (assuming the ROM is
mapped into memory at run-time, AND that the rom based code doesn't
care what "base address" it runs from). You can then get back to your
application simply by resetting the micro.

Failing either of the above, THE ONLY WAY to get back to SAMBA is to
jiggle the power WHILE TYING THE ERASE pin (NOT the Tst pin!). This
WILL ALSO CLEAR your entire application flash and restore the GPNVM
bits to defaults, which says boot from SAMBA ROM on the next reset. You
WILL NOT be able to return to your application simply by flipping the
GPNVM bit because your flash has been erased! (However, you can of
course, re-download it using the SAMBA windows client).

As I said, I don't have any experience on the 7S series micros, so I
don't know if it's different for them in regards which pin you jiggle
and whether the ROM is visible or not, ... but the above description IS
how the 7X series work, because that's how we do it (including on our
custom board).

Does that clear it up fo' everyone?

Cheers,
David. Start a New Thread

glad to be of some help Mike
----- Original Message -----
From: ğlar Aky
To: A...
Sent: Thursday, October 05, 2006 4:05 AM
Subject: [AT91SAM] Re: Custom Board and SAM-BA
--- In A..., "mjdistl" wrote:
> my custom board works fine on samba with sam7x256
> make sure you have a 1.5k pullup resistor to 3.3v and pin
> 3 on usb conn. power up your board with erase pin pulled
> high. power down remove erase jumper. power back up and
> when windows finds new hardware load the 6124sys driver
> from samba.

Thanks everyone. From your words I understand that SAM-BA should
definetly work with my custom board and double ( even triple ) check
my board and find the problem.

Thanks mjdistl. Your suggestion for the pull-up gave me a great help.

Best Ragards,
ar Start a New Thread