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.