Vybrid, eMMC, MQX

[axelrichter]

Hello,

I want to use eMMC memory on the Vybrid. The hardware interface itself is supported by the SDHC/MMC interface.

Does MQX support eMMC as well? It is not explicitly mentioned but I think it can be handled similar to SDHC cards? On the other hand there some people having trouble with the ESDHC driver on MQX, see https://community.freescale.com/thread/322240.

Best regards,

Axel Richter

[RadekS]

Hi Axel,

Unfortunately MQX ESDHC driver is older than eMMC specification.

This is also general reason, why eMMC is not correctly recognized.

However since eMMC is connected directly to MCU, you don’t need to care about recognizing card type.

In that case _esdhc_get_card_type() function could be simply replaced by specifying card type:

esdhc_device_ptr->CARD = ESDHC_CARD_MMC;

There could be also some issues in case of timing tolerances (according feedback from some of customers – it depends on particular eMMC type); however this should be solved with appropriate eMMC specification…

Unfortunately isn't true that eMMC is the same as SD card in different package.

Currently I do not know about any activity for implementing eMMC support. Of course, it will be high priority when we will start support any evaluation board with eMMC or when any customer will pay for that…

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MQX_SUPPORT

I hope it helps you.

Have a great day,
RadekS

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[axelrichter]

Hello,

thanks for the reply!

We also want to boot fromm eMMC. Does the Vybrid bootloader support eMMC or are there similar issues in detecting the card type.

Best regards,

Axel Richter

[RadekS]

Hi Axel,

Vybrid MQX bootloder example code is based on MQX sdcard (eSDHC) driver (Example describes how to load image from SD card). So, you can potentially meet with wrong recognizing of your eMMC. However this is not rule, it is possible that everything will work correctly on your side (with your eMMC).

There are already several versions of eMMC specification therefore it is possible that only some of eMMC devices are not recognized. Unfortunately this was not investigated and tested yet.

I hope it helps you.

Have a great day,
RadekS

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[axelrichter]

Thanks. Finally I'd rather use NAND SLC flash for my application, regardless of the much lower capacity.

[DavidS]

Hi Alex,

Currently MQX does not support eMMC directly.

Indirectly the SDHC controller and software drivers are "close" and a few customers have modified the initialization code to work with eMMC.  It seems that once initialized eMMC operates just like SD Card.

Hopefully someone else has done this and can share the code.

I will forward request to our MQX team as well.

Regards,

David

[axelrichter]

Hello David,

this is just what I found in the community on some older threads (see above) but I have hoped freescale has implemented in the meantime.

Thanks,

Axel Richter