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dan0
Associate II
Mar 27, 2020 6:52 PM UTC
Solved

Can't deference memory mapped qspi

I am using memory mapped mode of the QSPI peripheral on an STM32L452. I can see in the memory view at address 0x90000000 the bytes i expect. However, when dereferencing the pointer to that memory all i get is 0xFF's.

In the attached photo you can see I expect to read xAA, xAA, xBB,xBB,xCC,xCC ... and so on. You can see those bytes in the memory view, but all that i get is xFF.

This topic has been closed for replies.
dan0
dan0Best answer
Associate II
Mar 31, 2020 1:13 PM UTC

Hello All-

Thanks for the replys, but I've solved the problem. I had the wrong number of dummy cycles programmed (0 when i needed 8). This was on a N25Q256 spi flash.

4 replies

alister
Senior III
Mar 30, 2020 8:37 AM UTC

Perhaps the Memory window's accesses are adversely affecting it, and if not the mapped memory, perhaps the memory below is paged and impacting something. Try repeating from boot without the memory window.

dan0
dan0Author
Associate II
Mar 30, 2020 11:37 AM UTC

I tried from boot w/out a memory view but still read 0xFF. Thanks for the idea though.

Tesla DeLorean
Guru
Mar 31, 2020 1:08 AM UTC

Seems like you need to revisit your QSPI support code.

What chip is being used here?​

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dan0
dan0AuthorBest answer
Associate II
Mar 31, 2020 1:13 PM UTC

Hello All-

Thanks for the replys, but I've solved the problem. I had the wrong number of dummy cycles programmed (0 when i needed 8). This was on a N25Q256 spi flash.