sdio sd card write speed problem

[jimmjimmshen]

Posted on August 30, 2013 at 03:17

hi guys i'm new to stm32, i got a problem that i used sdio and fatfs to test maximum speed of write sd card, its only around 330kb/s but when i try to use sd card reader its up to 2mb/s, so i want to figure out why its so different between them and how can i fix it?

(i tried two ways of test: first use f_write function write 10k data once, second separate 10k data into 64byte package to send, result looks similar )i use dma mode 4bits bus #sdio-fatfs

[Tesla DeLorean]

Posted on September 02, 2013 at 14:46

finally, the 32-bit limit inherent in the ST code. I'm not sure whats this

Card capacity less that 2^32 bytes, as represented by uint32_t

[jimmjimmshen]

Posted on September 05, 2013 at 04:25

oh, that's right. But i still confuse that when i try to enable bypass mode like SDIO_InitStructure.SDIO_ClockBypass = SDIO_ClockBypass_Disable to set clock over 24mhz all sdio function did nothing and no response, whats this problem?