Mity CPU Platforms » MityDSP-L138 (ARM9 Based Platforms)

François Tremblay wrote:

Hi,

We have our own baseboard on which we plug a MITYDSP-L138F.

We are using a micro SD card on our baseboard for logging purpose.

Now, we have a customer who will use that reference design but want to replace the micro SD card with an eMMC onboard chip.

Is the same pins interface can be used with MITYDSP-L138F?

Yes, MMC0 can be used with an eMMC device. Do they plan to use all 8 data pins for the eMMC? What size eMMC devices are they looking for?

Is the Linux Kernel provided in MDK support it?

Yes, though there has been recent eMMC protocol changes from 4 to 5 so for brand new eMMC chips there is a small patch to add support. I'm assuming you are using the most recent MDK with the 3.2 kernel.
The patch was pushed to our kernel: https://support.criticallink.com/gitweb/?p=linux-davinci.git;a=commit;h=c2668792cc9815c3f6d347ebcc477c9bf4d60079

IS there any other customers of MITYDSP-L138F already using a eMMC onboard chip successfully?

Yes I know of at least one project doing this. I will check in with them to get their feedback.

Thanks

-Francois

Hi Francois,

I'm on the project Jon mentioned that is currently using eMMC with the MityDSP-L138F.

In addition to Jon's notes here are some details to consider:

• The 3.2 kernel for the L138 only supports the 4-bit data interface for eMMC, despite there being 8 data pins available. There may be support in a later kernel that could be backported, but we have not needed to look into that.
• Note that eMMC chips have on-chip controller firmware to manage ECC, bad block management, etc. The significance of this is that uncontrolled loss of power can affect future performance of this microncontroller firmware.

Please let me know if you have any questions or would like additional information.

Thanks,
\Greg

Thanks guys for information