topic Re: maximum read/write speed with SDHC controller in Kinetis Microcontrollers

maximum read/write speed with SDHC controller

monXii — Fri, 04 Nov 2011 15:45:32 GMT

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 ..

Re: maximum read/write speed with SDHC controller

monXii — Mon, 07 Nov 2011 15:51:06 GMT

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

thanks!

Re: maximum read/write speed with SDHC controller

monXii — Wed, 30 Nov 2011 17:04:16 GMT

hello again..

i bought a 4gb class 10 mico sdcard..

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

but reading is 2x so fast

reading 10240 bytes in ~ 7 ms.

so maximum read speed is 1,463 MByte ..

and this is not multi block read ..

Re: maximum read/write speed with SDHC controller

Carvic — Fri, 02 Dec 2011 09:46:42 GMT

Hello, Can you post your project code?

Re: maximum read/write speed with SDHC controller

emilien — Mon, 06 Aug 2012 19:12:25 GMT

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