XCore Exchange

Hi,

What is the memory zone not affected by the tools on XU216 processor ?

Based on dfu.xc file I suppose that the range is 0x7FFC8 to 0x7FFFF. After receiving a XMOS_DFU_RESETINTODFU command I write specific pattern in this area, but after CPU reset this area is most of the time reset to 0.
How to explain that this supposed area is reset after a CPU reset writing in PLL register ?

I try to write directly in this area just before reboot and the result is the same

#define FLAG_ADDRESS 0x7FFCC

unsigned x =0x11042011;
asm volatile("stw %0, %1[0]" :: "r"(x), "r"(FLAG_ADDRESS));
device_reboot(c_audioControl);

I also test removing the pattern writing in DFU handler, but the area is always reset to 0 after reboot

Any ideas how to explain this problem ?

Nobody to explain at least how this zone is set to 0 (except by a voluntary writing) ?

Thanks

I think it will be best for you to raise a support ticket using the xmos.com website so that the proper staff member can reply on this low level technical question. On a privileged few will know the correct answer. Please update this post once you receive a reply.

Thanks for your answer.
I already raised a support ticket and the answer was to post on the forum to get an answer !!!

Can you use the flash or OTP for such storage?

https://www.xcore.com/viewtopic.php?t=5573

I just use the supposed "non touched memory area" to test if device has to enter in DFU mode (as in xcore evaluation board).
This area is reset just after xcore reboot and that's the reason why I would like to know what can be the reason.

Not an assembly programmer with XMOS but is your assembly code working correctly?

Can you confirm this through debugging?

See AN10022 which shows the following:

Hi,

I found where was the problem (a pointer that overflowed when restarting), but I'm still interested in having information about this area

Thanks