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sdcard example fails running from OCRAM

Question asked by Jack King on Jul 10, 2019
Latest reply on Jul 25, 2019 by jeremyzhou

I am trying to use fatfs and usdhc module while executing from OCRAM on IMXRT1052.

This can be tested using the sdk example "sdcard_fatfs_freertos" and switching the memory config to use SRAM_OC as "RAM" region instead of the default of SRAM_DTC.

 

This test will fail on f_mkfs unless caching for OCRAM is turned off using something like:

    SCB_DisableICache();
    SCB_DisableDCache();

Obviously, this isn't really a useful fix, as the performance without caching is horrible.

 

Looking at AN12042   it specifically states that usdhc uses ADMA which takes care of cache coherency, so I'm not sure why the example doesn't run without change from OCRAM.

 

What configuration should be made (besides disabling cache) to allow the example to execute correctly?

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