Strange setting for writing file into SD Card

g_macaluso — Fri, 03 Jan 2020 13:25:43 GMT

Hello everyone,

I'm developing an application which has to save some file to a SD Card.

At the moment I have some problem writing file into the SD Card.

I read some posts which suggested to drecrease the clock of the MCI peripheral.

I tried to decrease the clock and now I can write files into the SD Card.

The strange thingh is that in order to be able to write files into the SD Card I have to set the field PCLKDIV of PCLKSEL register to 8, but 8 is not a supported value.

As specified into the User Manual for LPC408x/407x, permitted value of PCLKDIV are 0, 1, 2, 4.

Can someone explain me how it it possible, and what I'm doing wrong?

And how can I decrease the clock of the MCI setting the field CLKDIV of CLOCK register?

Thanks a lot in advance.

Giovanni.

Re: Strange setting for writing file into SD Card

soledad — Fri, 03 Jan 2020 19:06:01 GMT

Hi,

Unfortunately, we cannot guaranty the behavior using another value. The values supported are 0, 1, 2, 3 and 4.

Did you test setting the value 1 or 4? Could you please try?

I suggest you use the lpcopen SD card demo code, please download lpcopenhttps://www.nxp.com/support/developer-resources/microcontrollers-developer-resources/lpcopen-libraries-and-examples/lpcopen-software-development-platform-lpc40xx:LPCOPEN-SOFTWARE-FOR-LPC40XX
in side package, there is demo app_sdmmc_meas, This example measures the performance of SD/MMC raw read & write operations.

Have a great day,
Sol

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topic Re: Strange setting for writing file into SD Card in LPC Microcontrollers

Strange setting for writing file into SD Card

Re: Strange setting for writing file into SD Card