About KMaen

KMaen · 2021-04-25

I am running Thumb-2 instruction code on STM32F750N8.I am seeing non-negligible performance number variation depending on whether I insert one NOP right before a tight loop (and changing the address of each instruction by halfword). Other parts of th...

KMaen · 2021-04-22

I am using STM32F7508-DK and using Ext Flash connected to QSPI. It is mapped to 0x90000000~ region which is by default covered with cache, but for some reason, it seems like it is not benefitting as much compared to on-chip SRAM or SDRAM connected wi...

KMaen · 2021-04-09

Hi, I am struggling to make QSPI+Ext Flash and DMA to work for several days, but having issues.I was using BSP library for both external SDRAM (with FMC) and Flash with QSPI.However, BSP library had DMA read/write for FMC SDRAM, but not for QSPI Flas...

KMaen · 2021-03-25

I am currently using Linux and compiling my project using my own Makefile, with libraries generated via STM32CubeMX from my Windows machine. I am trying to use CMSIS's arm_mat_mult_f32() function but it is not working. I suspect I am passing the wron...

KMaen · 2020-11-10

I am working with STM32F&508-DISCO, which is said to have external Flash of size 16MB connected through QSPI. I am trying to read from it, but it is not working.I tried running this: https://github.com/STMicroelectronics/STM32CubeF7/blob/master/Proje...

KMaen · 2021-04-22

Update to this: I spent some time today with the logic analyzer to see what was going on with the QSPI Flash. (SDRAM's tip was not exposed and QSPI had similar cache problem so I looked at the QSPI flash instead)There was indeed a prefetcher involved...

KMaen · 2021-04-22

Update to this: I spent some time today with the logic analyzer to see what was going on with the QSPI Flash.There was indeed a prefetcher involved (If anyone's interested, when streaming data, it was first fetching 2 cache lines, and on each access,...

KMaen · 2021-04-22

I left the MPU as default, and according to this: https://iq.direct/datasheets/STM32x7%20Cache%20Appnote.pdf QSPI region has cache enabled by default.

KMaen · 2021-04-09

Also, if I were to use memory mapped mode + DMA, is my current setting (e.g., using initialization code from STM32CubeMX) correct? Are there any example using memory mappend mode +DMA for QSPI Flash? Thank you!

KMaen · 2021-04-09

Thank you for the answer! Then, would it be as simple as putting the QSPI in memory-mapped mode and copy-pasting the code structure for SDRAM DMA? Are there any performance different between direct mode vs. memory-mapped indirect mode?

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Performance varies notably when the code alignment changed by 2 bytes?

Ext Flash w/ QSPI seems like it is not benefitting as much from the cache for some reason.

QSPI+Flash with DMA not working properly.

CMSIS functions not working (what is the right compilation flag to give?)

Reading from external Flash with QSPI not working.

Re: Weird cache behavior in SDRAM+FMC. Is the prefetcher doing something weird?

Re: Ext Flash w/ QSPI seems like it is not benefitting as much from the cache for some reason.

Re: Ext Flash w/ QSPI seems like it is not benefitting as much from the cache for some reason.

Re: QSPI+Flash with DMA not working properly.

Re: QSPI+Flash with DMA not working properly.