LPC1837 HS USB to SD Card performance

[DavidS]

I am asking this for a customer.

I do not have a LPC1837 Xplorer board to run the demo's on.

Customer asking the following:

Can you tell me the data rate you can run with you eval board (LPC1837 explorer) on this port to download/upload a file from the USB to the SD card?

I'm sure the performance is dependent on the SD Card type so please let me know what type you use for testing.

When I visit the OM13061 Product page and click Buy....it does not list the LPC1837 Xplorer board.  Is it EOL'ed or just a web page issue?

I did find Mouser has board for $100 and pointed customer to that site.

Regards,

David

NXP FAE

[DavidS]

Hi Tyler and Bernhard,

Thank you so much for your inputs and data.  I think this should be good for customer.

Tyler, I will wait to see if customer needs example software before asking you for it. 

Regards,

David

[tyler_drazich]

Hi David,

I cannot speak for the NXP examples, but testing with my own code, I achieve a sequential read speed of 9.5 MB/s and write of 6.1 MB/s going through USB mass storage using the LPC1857 and the SDIO interface. The test SD card is a Lexar class 10 32GB.

I've compared this to a Vivitar SD card reader which achieves 21.1 MB/s sequential read and writing of 11.1 MB/s. I know of several limitations within my code that could be improved to get closer to this off-the-shelf reader.

If you or your customer is interested, I can put together a demo of my software that runs as a USB mass storage device for the LPC18S37 (OM13076) evaluation board with the shield as described above? Let me know, I'd be glad to help.

Best Regards,

Tyler Drazich

DZX Designs

[jmccabe]

Tyler,

Sorry this is so late in the day, but if you're still around this sort of stuff, I've got the OM13076 board with the OM13082 General Purpose shield and trying to get the USB SD/MMC example from the LPCOpen package (that says it's for LPC1837/LPC18S37 - lpcopen_3_02_lpcxpresso_xpresso1837) going. If you can either share or advise on what needs doing to get this to work, I'd appreciate it.

John 

[jmccabe]

FWIW I found the answer; it seems there is a flaw in the OM13082 construction as described here.. https://community.nxp.com/thread/441365 

[bernhardfink]

Hi Tyler,
the numbers you achieve are quite OK, not much you can do to improve it.

This is our USB-2-SD card test result with 51MHz SDIO clock:

The SDIO interface itself with specific cards could achieve higher rates (9 Mib/s write, 18 Mib/s read), but in combination with the USB we have achieved (only) the numbers above.

Regards,

Bernhard.

[bernhardfink]

LPCXplorer boards are not (longer) in our store, but can be bought from NGX or other suppliers like Mouser.

The write performance depends of course on the SD card performance but also on the way you implemented this in software. The USB throughput as well as the speed on the SDIO interface is for sure not the best one in our examples which you find for the Xplorer or other board. There are subcontractors who have this knowledge and they could be involved if it comes to throughput as a key product requirement.

We might find benchmarks for USB and SDIO throughput based on tests we did, but we would not be able to deliver example code to a customer.

From our side there is no focus at the moment on this setup, it depends on the importance of the project/customer how far we would engage.

There is an LPC18S37 board available (OM13076), the 'S'-feature of this chip mustn't be used. On this board you can add an OM13082 general purpose shield which has an SD card slot.

But most likely the example which is available for the Xplorer board does not run in the first step on this setup.

Regards,

Bernhard.

[brendonslade]

Actually Xplorer boards are still available. The Xplorer4330 board (LPC4330-Xplorer Board|NXP, OM13027) is available ... nxp.com is currently (incorrectly) showing it as unavailable due to a problem with the internal order code options that we are trying to fix.

The Xplorer board for LPC1837 is available, but only as part of the dual USB solution kit:

LPC1837 Dual-USB Host/Device Solution|NXP

As Bernhard mentions, LPCXpresso boards are available for the versions of the LPC43xx and LPC18xx with flash. See LPCXpresso Boards|NXP . The LPC General Purpose shield has an SD card slot, and the LPCOpen package for the LPCXpresso18S37 board does include an example of using the SD/MMC interface, although not for this specific benchmark.

[DavidS]

Thank you Brendon.

Regards,

David

[DavidS]

Hi Bernhard,

Thank you for the information and history and suggestions.

If I get some numbers I will post back under what conditions they are received.

Regards,

David