Neuros Forums

SD v. MMC

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Topic URL: http://www.neurosaudio.com/community/forum/topic.asp?TOPIC_ID=6332
Printed on: 03/24/2006

Topic:

Topic author: JoeBorn
Subject: SD v. MMC
Posted on: 07/15/2005 8:52:21 PM
Message:

I'm still a little confused about compatibility between MMC and SD as it pertains to this discussion.

I know the 442 can read from MMC cards, so can't we just require an MMC card for the Linux boot media? Won't that get around the proprietary issues?

jborn (at) neurosaudio.com

Replies:

Reply author: spudmonkey
Replied on: 07/18/2005 07:15:01 AM
Message:

quote:
Originally posted by JoeBorn
I'm still a little confused about compatibility between MMC and SD as it pertains to this discussion.

I know the 442 can read from MMC cards, so can't we just require an MMC card for the Linux boot media? Won't that get around the proprietary issues?

I don't think booting is the issue. If the closed source, proprietary bootloader loader can read SD, then you can boot from SD.

The issue is with Linux. Ideally you would also like to use the SD to hold the Linux filesystem as well. In order to do that, however, you would have to an an SD driver in Linux. Since SD is a closed, specification, there is no open SD driver for Linux. There is, however, an open MMC driver. So I think the summary is:

MMC: proprietary code can boot from it; open Linux can use it
SD: proprietary code can boot from it; open Linux code
cannot use it without a driver.

Greg

Reply author: mrshoe
Replied on: 07/28/2005 5:05:13 PM
Message:

Has a decission been made yet as to CF support?

Shoes

Reply author: JoeBorn
Replied on: 07/28/2005 11:15:29 PM
Message:

v1 of the 442 has SD. the 442 is quite far along, we are already beta testing it. CF is the likely choice for v2.

quote:
Originally posted by mrshoe

Has a decission been made yet as to CF support?

Shoes

jborn (at) neurosaudio.com

Reply author: Yono
Replied on: 07/29/2005 07:32:23 AM
Message:

So when the firmware is fully converted to linux, the SD slot will mostly be used with MMC cards? (if not always)

-- 'Microsoft Works is an Oxymoron'

Reply author: spudmonkey
Replied on: 07/29/2005 10:15:35 AM
Message:

quote:
Originally posted by Yono

So when the firmware is fully converted to linux, the SD slot will mostly be used with MMC cards? (if not always)

I hope that is not the case in the long run. MMC cards are much slower: 20HMz x 1 bit transfer vs. 25MHz x 4-bit transfers. Potentially 5x slower. MMC cards are fine for development, but they may not could handle realtime streaming multimedia applications.

Also, MMC cards are nearly obsolete are not as easy to find.

Greg

spudmonkey

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