eMMC Support in NuttX

[Angus Jull <an...@gmail.com>]

Hey everyone,

This is my first email to this forum in case you haven’t seen my name
before - I work with Matteo on CUInspace and we’re just sorting out the
choice of non-volatile storage for the rocket.

I was trying to figure out if eMMC 4.5/5.1 is supported by NuttX. In
particular I was interested in the STM32H743 which has SDMMC ports that
support SDIO/eMMC and use them in basically the same way, seemingly just
with a difference in some configuration. That chip is marked as having
support for the SDMMC peripheral in NuttX so that makes me think it should
just work as is. I'm pretty new to SD and eMMCs and mostly new to NuttX as
well so I thought I would double check my understanding.

Something that's confused me is the note in the "OS Components" -> "Device
Drivers" docs about MMCSD that says that only SDIO/MCI and SPI are
supported, though there's clearly been support for eMMCs in old PRs and
multiple boards. From my understanding, SDIO & the SD card protocols are
distinct from the eMMC protocol which makes me wonder if there’s
intricacies in integrating an eMMC chip. If anyone knows more about how
eMMCs fit into this driver I would be really interested in learning more.

Best wishes,

Angus

eMMC Support in NuttX

["Alan C. Assis" <ac...@gmail.com>]

Hi Angus,

Yes, NuttX supports eMMC, but it depends on the driver from each MMC to
support faster modes.

See the example of an issue some faced some time ago:

https://lists.apache.org/thread/rf9lzwdckbkrh4l17m1lmk8tlwfqrqk9

In our company we use NuttX with an eMMC chip from SkyHigh and it works
fine.

BR,

Alan

On Fri, Oct 18, 2024 at 12:01 PM Angus Jull <an...@gmail.com> wrote:

> Hey everyone,
>
> This is my first email to this forum in case you haven’t seen my name
> before - I work with Matteo on CUInspace and we’re just sorting out the
> choice of non-volatile storage for the rocket.
>
> I was trying to figure out if eMMC 4.5/5.1 is supported by NuttX. In
> particular I was interested in the STM32H743 which has SDMMC ports that
> support SDIO/eMMC and use them in basically the same way, seemingly just
> with a difference in some configuration. That chip is marked as having
> support for the SDMMC peripheral in NuttX so that makes me think it should
> just work as is. I'm pretty new to SD and eMMCs and mostly new to NuttX as
> well so I thought I would double check my understanding.
>
> Something that's confused me is the note in the "OS Components" -> "Device
> Drivers" docs about MMCSD that says that only SDIO/MCI and SPI are
> supported, though there's clearly been support for eMMCs in old PRs and
> multiple boards. From my understanding, SDIO & the SD card protocols are
> distinct from the eMMC protocol which makes me wonder if there’s
> intricacies in integrating an eMMC chip. If anyone knows more about how
> eMMCs fit into this driver I would be really interested in learning more.
>
> Best wishes,
>
> Angus
>