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Unable to exceed the SCLK for SD card beyond 2 MHz

viney chaddha1
Expert 1280 points
Other Parts Discussed in Thread: MSP430F5529

Hi All,

I am using MSP430F5529 to write incoming data onto a SD Card.

I am unable to exceed the SCLK speed for the SDHC card beyond 2 MHz, If i increase the speed beyond 2 MHz the card response is 0x05 . I have even used class 10 card for this and changed the make of the cards. All respond with 0x05 beyond 2 MHz. At speeds upto 2 MHz there is no issue in writing. Could anyone please suggest the root cause of this problem.

Regards

Viney Chaddha

  • 0
    TI__Guru 56685 points
    Hello Viney,

    The best way to start debugging this is capture what is going on the SPI lines between the MSP430 and your end device. A Logic Analyzer or an O-scope with the capability will do the trick. From there we can find out of one device is stalling the bus or sending out wrong data. Some other questions to consider:

    What are your clock settings on the MSP430?
    Which clock are you using for the USCI module?
    What voltage are you operating the MSP430 at?
    Is VCORE set to an appropriate level for the frequency you are operating?
    Are you moving data from the SPI RX buffer quick enough, before the next Rx?

    Regards,
    JH
  • 0
    Guru 24395 points
    You say that the card response is 0x05 but you don't way what command you sent. This response indicates an illegal command and that the card is in the idle state. I suspect that you are attempting to initialize the card with too high of a clock speed.

    The clock speed must be below 400KHz while initializing.
  • 0 in reply to David Schultz
    Expert 1280 points
    card in initialized with 400 k Hz and initialize. starts receiving and storing data but sometime is stops and send oxo5 for cm24 atCMD54
    can you list doun pooble reasons
    Regars
  • 0 in reply to viney chaddha1
    TI__Guru 56685 points
    Viney,

    Are you still having issues? Have you been able to scope the lines as suggested above to narrow down the issue? Do you have answers to the questions above for debugging purposes?

    Regards,
    JH
  • 0 in reply to Jace H
    Expert 1280 points
    Jace,
    I resolved the issue. A very stupid mistake that I had made was causing the issue.
    The clock at higher frequency was unstable and that's why the card was not working as I was expecting it to. This mistake was that the clock was not initialized properly. When that was corrected I am able to achieve 12 MHz of clock without any issues.
    Thanks for your help.
    Regards
    Viney Chaddha

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