XU216 memory range guarenteed to be untouched and DFU

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
cl-b
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XU216 memory range guarenteed to be untouched and DFU

Postby cl-b » Wed Jan 09, 2019 2:44 pm

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 ?
cl-b
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Postby cl-b » Thu Jan 17, 2019 6:38 pm

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

Thanks
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mon2
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Postby mon2 » Fri Jan 18, 2019 5:17 pm

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.
cl-b
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Postby cl-b » Mon Jan 21, 2019 8:26 am

Thanks for your answer.
I already raised a support ticket and the answer was to post on the forum to get an answer !!!
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mon2
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Postby mon2 » Mon Jan 21, 2019 11:00 am

Can you use the flash or OTP for such storage?

viewtopic.php?t=5573
cl-b
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Postby cl-b » Mon Jan 21, 2019 11:05 am

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.
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mon2
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Postby mon2 » Mon Jan 21, 2019 8:54 pm

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:
xmos_assembler.png
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cl-b
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Postby cl-b » Fri Feb 01, 2019 4:30 pm

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

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