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SNNV
SNNV
Associate
October 30, 2019
Question

EMMC support for greater than 2 gb

  • October 30, 2019
  • 1 reply
  • 1047 views

We are using stm32f769 with 8 gb EMMC , from other forums we understood that there is no HAL support for emmc for more than 2 gb , we are hard coding the emmc block count to 0x773594 and emmc block size to 0x200 . These values are calcuated in accordance to 8 gb storage . But the emmc card is full after 12 mb . Does anyone have a solution for emmc greater than 2 gb .

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1 reply

Tesla DeLorean
Tesla DeLorean
Guru
October 30, 2019

Fullness is something the file system would be managing, not sure I recall there being a byte vs block offset issue with the eMMC command interface, definitely have much large devices working on L4/F4/F7/H7 platforms.

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SNNV
SNNVAuthor
Associate
October 31, 2019

When we tried reading EXTCSD register ,we are getting response timeout so we hardcoded the contents below.

The hard coded changes made are the following

    hmmc1.MmcCard.BlockNbr = 0x773594

   

    hmmc1.MmcCard.BlockSize = 0x200 

    hmmc1.MmcCard.LogBlockNbr = 0x773594

    hmmc1.MmcCard.LogBlockSize = 0x200 

capacity is changed to 0xFFFFFFF0U (4GB) from 0x80000000U(2 GB)

All the above parameters are calculated for the files to be stored till a limit of 4 GB , but the EMMC stores 12 MB of files. Beyond 12 MB when fopen call returns FR_DISK_ERROR .

Are we missing any other parameters that needs to be addressed ?

Tesla DeLorean
Tesla DeLorean
Guru
October 31, 2019

Sounds like it is scaling the block address.

Need to change the card type settings so it doesn't multiply.​

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