Ethernet -> SD/MMC DMA (LPC2368 vs AT91SAM7xxx)

Development Boards MicroMod
1

Hi All,

I want to implement an Ethernet → SD/MMC hw, where every incoming ethernet packet is stored on a SD/MMC card, until it gets full.

The incoming data rate on the ethernet is ~1 MB/s.

I know LPC2368 has DMA support for data transfer from/to SD/MMC.

What about AT91SAM7xxx? I’d prefer the DMA approach, but couldn’t find any info about SD/MMC DMA on the AT91SAM7.

Thanks!

2

The AT91SAM7 chips all have DMA controllers on the SPI peripherals. I don’t know of any that have direct support for memory cards, so you’d have to use SPI.

3

The lpc2368 has an special build mmc interface. Most popular Ethernet stacks are UIP and LwIP. The first on is an more lighter Ethernet stack and supports most of the basic stuff. UIP and lwIP plus an freertos operating system can be found at www.freertos.org. There is also one on the net with uCos as operating system. The AT91SAM7X256 supports both UIP as lwip, but I’m not sure if the lpc2368 support lwip yet. Someone on the net claimed to have an lwip port on the lpc2378 without an operating system.

4

The lpc2368 has an special build mmc interface.

I believe this is important to consider, since SD/MMC cards seem to be limited to 10’s of kbytes/second in regular SPI mode.

5

Cannibal:

The lpc2368 has an special build mmc interface.

I believe this is important to consider, since SD/MMC cards seem to be limited to 10’s of kbytes/second in regular SPI mode.

I don't know where you heard that, but I don't think it is true. I've seen various posts by people using cards in SPI mode who were getting much higher date rates.
6

Cannibal wrote:

Quote:

The lpc2368 has an special build mmc interface.

I believe this is important to consider, since SD/MMC cards seem to be limited to 10’s of kbytes/second in regular SPI mode.

I don’t know where you heard that, but I don’t think it is true. I’ve seen various posts by people using cards in SPI mode who were getting much higher date rates.

You’ve got me interested since I’m looking for this.

Could you post a link for using FAT over SPI mode at rates over 100kbyte/sec?

7

Cannibal:

Cannibal wrote:

Quote:

The lpc2368 has an special build mmc interface.

I believe this is important to consider, since SD/MMC cards seem to be limited to 10’s of kbytes/second in regular SPI mode.

I don’t know where you heard that, but I don’t think it is true. I’ve seen various posts by people using cards in SPI mode who were getting much higher date rates.

You’ve got me interested since I’m looking for this.

Could you post a link for using FAT over SPI mode at rates over 100kbyte/sec?

I can't seem to find the posts that I've seen before. I think I saw them on the EFSL forum ([http://sourceforge.net/forum/forum.php?forum_id=447844](http://sourceforge.net/forum/forum.php?forum_id=447844)) but am not sure as I'm not finding them today.
8

Cannibal wrote:

Quote:

Cannibal wrote:

Quote:

The lpc2368 has an special build mmc interface.

I believe this is important to consider, since SD/MMC cards seem to be limited to 10’s of kbytes/second in regular SPI mode.

I don’t know where you heard that, but I don’t think it is true. I’ve seen various posts by people using cards in SPI mode who were getting much higher date rates.

You’ve got me interested since I’m looking for this.

Could you post a link for using FAT over SPI mode at rates over 100kbyte/sec?

I can’t seem to find the posts that I’ve seen before. I think I saw them on the EFSL forum (http://sourceforge.net/forum/forum.php?forum_id=447844) but am not sure as I’m not finding them today.

Thanks for the info, I’ll take a look.