2008-08-05 06:48:21     Writing Speed of SD Card

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2008-08-05 06:48:21     Writing Speed of SD Card

Pei Chen (CHINA)

Message: 59935   

 

Hi,

 

I am trying to record a realtime data stream by BF537.

 

I want to know the max writing speed of SD card by BF537, my data speed varies from 3MB/s to 6MB/s.

 

Can this job be done by the uclinux driver right now, or must I add a CF card for this job?

 

 

 

Thanks

 

 

 

Chen,Pei

 

Beihang University

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2008-08-05 08:19:41     Re: Writing Speed of SD Card

Michael Hennerich (GERMANY)

Message: 59937   

 

>3MB/s to 6MB/s.

 

On BF537 with SPI MMC

 

No Way ... use a CF Card.

 

-Michael

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2008-08-05 08:50:04     Re: Writing Speed of SD Card

Pei Chen (CHINA)

Message: 59938   

 

Thank you Michael.

 

Could SD on BF548 be much faster than that?

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2008-08-05 10:41:47     Re: Writing Speed of SD Card

Michael Hennerich (GERMANY)

Message: 59941   

 

BF548 features an SDIO controller.

 

SD card throughput is much faster - but so far I havn't done any benchmarks.

 

-Michael

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2008-08-07 10:44:30     Re: Writing Speed of SD Card

Steve Strobel (UNITED STATES)

Message: 60105   

 

I seem to have trouble reading/writing to SD realtime at just 32KB/sec.  Writing to ramdisk or USB flash drive works fine.  Is SD on a BF537 really that slow, or do I have something wrong?

 

Steve

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2008-08-07 12:27:42     Re: Writing Speed of SD Card

Frank Van Hooft (CANADA)

Message: 60108   

 

Looking at some older (several months old) notes, I measured SD read & write speeds on the BF537 at:

 

write: 1.4 MBytes/s

 

read: 2.8 MBytes/s

 

Small filesizes can really slow things down - make sure you're using large files for your read & write speed tests.

 

These tests were done with the CPU idle, doing nothing except accessing the card.

 

Also, try different cards. I have one card with "133X Speed" proudly emblazoned across its front. But it actually runs at about a tenth the speed of my other cards - I've no idea why.

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2008-08-07 13:28:53     Re: Writing Speed of SD Card

Steve Strobel (UNITED STATES)

Message: 60111   

 

My processor is really heavily loaded, so that might have something to do with it.  I will try killing some of the other processes and testing again.  Thanks for the feedback.

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