MMU unit enable in STM32F7

[echelon2010]

Posted on November 20, 2015 at 22:05

Hello. I have noticed that in the cubef7 examples many projects starts with MPU_Config() function . Is it necessary to use MPU unit in STM32F7? And the same question about L1 cache. Can i don't use it? Thank you.

[Nesrine M_O]

Posted on November 23, 2015 at 14:17

Hi dmitriev.artyom

In fact, we modify MPU attributes, in order to perform data coherency between L1 (Cache) and L2 (system memory).  -Syrine-

[echelon2010]

Posted on November 23, 2015 at 15:03

Must i use L1 cahe and mmu, if i want to execute code from qspi nor flash? I am trying to execute code without mmu, and the program didn't work properly. And gdb server can't find my controller after i flash the code into external flash. 

[Nesrine M_O]

Posted on November 24, 2015 at 10:33

Hi  dmitriev.artyom,

Must i use L1 cahe and mmu, if i want to execute code from qspi nor flash? • In fact the STM32F7 Quad-SPI interface address is starting from 0x9000 0000 in the memory mapped mode, which it is an executable area so the remap is not needed, as result the MPU is not needed.  • The Quad-SPI is mapped on AXI BUS and can benefit from L1-cache. This allows to execute the code and load the data from QuadSPI with good performances so it recommended to activate L1 cache for better performance results. I'd highly recommend you to have a look to the  

http://www.st.com/web/en/catalog/tools/FM147/CL1794/SC961/SS1743/LN1920/PF262415?s_searchtype=keyword

 that presents the STM32F7 global architecture as well as the memory interfaces and features, also provides a software demonstration of the architecture performance of the STM32F7 Series devices in various memory partitioning configurations (different code and data locations) particularly for QSPIAlso try the QSPI example under: STM32Cube_FW_F7_V1.2.0\Projects\STM32746GDiscovery\Examples\QSPI\QSPI_ExecuteInPlace-Syrine-