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eMMC in 8 bits Wide bus mode

Question asked by Neouchi.Radwan on Jan 4, 2017
Latest reply on Jan 17, 2017 by Vermaak.Dirk



I'm using a STM32L4 and CubeMx to generate eMMC code, either the 8 bits wide bus mode configuration isn't supported and should be configured manually.


I was able, with few code modification, to use the SD auto generated code to communicate with the eMMC in 4 bits mode, but when trying to move to 8 bits mode my f_mount() function returns "FR_NO_FILESYSTEM" error.


To adapt the SD code to an eMMC i've added few eMMC appropriate commands to configure its Power Class and bus wide by a switch command and it worked without any issue.


To move to 8 bits mode, I added some more current (needed as said in the eMMC datasheet) and passed the 8 bits mode argument instead of 4 bits one. Then in the HAL_SD_MspInit() and HAL_SD_MspDeInit() functions I added the 4 additive used GPIO pins init and DeInit procedure...


What are the manually modifications needed to use the 8 bits bus wide mode? And did I missed some of this neede modifications?