SDIO high-speed problem

r01525050 · ‎2013-10-06

Posted on October 07, 2013 at 07:24

hi there,first,apologized for my poor English.I'm a beginner of STM MCU.

I have a problem when I want to turn on SD card High-speed mode.

I port FATFS on my board successfully and I can send data into my SDHC card successfully.

When I want to change my SDIO_CLK from 25MHz to50MHz,I encountered some problem.

After I set SDIO_InitStructure.SDIO_ClockBypass from SDIO_ClockBypass_Disable to SDIO_ClockBypass_Enable and called function SD_HighSpeed(),my program runs Smoothly.

But after I checked the SD card ,I found that It wasnt written anything by Fatfs.

Can anyone that is familiar with SDIO module give me some tips about it?

My card is Sandisk class 10 16GB SDHC,and my board is STM32F4_EVB with STM32F417IG.

Thanks for your patient.

frankmeyer9 · ‎2013-10-07

Posted on October 07, 2013 at 10:41

When I want to change my SDIO_CLK from 25MHz to50MHz,I encountered some problem.

According to the datasheet, the maximal clock frequency is 48MHz. But more important than this 4% overrun - is your layout/wiring appropriate for 48/50MHz ?

Use a scope, and check the signal quality (at the SD card pins), taking care to have proper termination for your probe. I'm quite sure this will reveal your problem.