XU216 memory range guarenteed to be untouched and DFU

Technical discussions around xCORE processors (e.g. xcore-200 & xcore.ai).
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cl-b
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XU216 memory range guarenteed to be untouched and DFU

Post by cl-b »

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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Post by cl-b »

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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Post by mon2 »

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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Post by cl-b »

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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Post by mon2 »

Can you use the flash or OTP for such storage?

https://www.xcore.com/viewtopic.php?t=5573
cl-b
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Post by cl-b »

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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Post by mon2 »

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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xmos_assembler.png
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cl-b
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Post by cl-b »

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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