maximum read/write speed with SDHC controller

キャンセル
次の結果を表示 
表示  限定  | 次の代わりに検索 
もしかして: 

maximum read/write speed with SDHC controller

2,238件の閲覧回数
monXii
Contributor III

Hello all,

i experiment with the SDHC controller on the K60.

K60 runs with 100 MHz and SDHC controller with maximum speed (50MHz).

 

I am using a normal sd card (2gb) in 4 bit mode.

My file system is fatfs..

 

My max. write speed is 10240 Byte in ~ 59ms..

My max. read speed is 10240 Byte in ~12ms.. (withouf fs ~9ms)

 

That are about 173,5 kByte / s writing and

853,3 kByte / s reading ..

 

what are your values?

i can't believe that this is the maximum ..

0 件の賞賛
返信
4 返答(返信)

1,272件の閲覧回数
monXii
Contributor III

mh, i think my sd card is the bottle neck..

 

on my scope i see some clk cycles with 20ns (50 MHz...),

but my scope told me the average clk speed is ~ 16,7 MHz ..

 

so the controller waits for the card to be rdy.. ?!

 

but if you have some time, pls test your max. speed for reading / writing 10240 bytes ..

would interest me :smileyhappy:

 

thanks!

0 件の賞賛
返信

1,272件の閲覧回数
monXii
Contributor III

hello again.. :smileyhappy:

i bought a 4gb class 10 mico sdcard..

 

write speed is nearly the same.. not really faster =/

but reading is 2x so fast :smileyhappy:

 

reading 10240 bytes in ~ 7 ms.

so maximum read speed is 1,463 MByte ..

 

and this is not multi block read .. :smileywink:

0 件の賞賛
返信

1,272件の閲覧回数
Carvic
Contributor I
Hello, Can you post your project code?
0 件の賞賛
返信

1,272件の閲覧回数
emilien
Contributor III

Hi,

 

I have very similar results. The weird thing is that two sdcards of same classes will give different results (write speed). 

Maybe this could explain the behavior:

"The memory of a card is divided into minimum memory units. The device writes data onto memory units where no data is already stored. As available memory becomes divided into smaller units through normal use, this leads to an increase in non-linear, or fragmented storage. The amount of fragmentation can reduce write speeds, so faster SD memory card speed standards help compensate for fragmentation."

I'm also looking for multi-block operations, do you know when the driver updates are expected ?

 

Best regards

 

0 件の賞賛
返信