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AM3874 no SD clock

Poh Boon Teo
Intellectual 710 points
Other Parts Discussed in Thread: AM3874, AM3894

Hi,

We have built a custom board based on AM3874 and was attempting to start uboot from the SD card.

However, it did not boot up and I went to probe the SD clock with the osciilloscope upon powering up

I saw that there wasn't trace of a clock activity.

I compared with a previous design based on AM3894 and I was able to get some clock activity upon powering up.

What am I missing here? Can someone provide me some direction?

Thanks and regards,

pb

 

 

  • 0
    TI__Guru**** 170625 points

    Hi Poh,

    AM387x device has 3 MMC/SD interfaces: MMC/SD0, MMC/SD1 and MMC/SD2. Are you using the MMC/SD1 interface?

    Poh Boon Teo said:
    probe the SD clock with the osciilloscope

    Poh Boon Teo said:
    I saw that there wasn't trace of a clock activity.

    Which clock do you refer? Is it the functional clock coming from the device PRCM? Or is it MMC_CLK pin?

    Make sure that the BTMODE[4:0] pins are configured for MMC boot: 10111

    BR
    Pavel

  • 0 in reply to Pavel Botev
    Intellectual 710 points

    Hi Pavel,

    I have connected the MMC interface to MMC/SD1 interface as shown in the reference design.

    The clock I am referring to is the MMC_CLK pin and I have also configure the BTmode to 10111.

    One deviation from the reference design is that I do not connect the WP pin but I do not think that is the problem.

    Please advise on any other thing I can look out for.

    Thanks and regards,

    pb

  • 0 in reply to Poh Boon Teo
    TI__Guru**** 170625 points

    Poh,

    Do you have something on the console output?

    How did you create your SD card? Please note that the last EZSDK version for AM387x device is EZSDK 5.04.00.11. We have a mksdboot.sh script inside the EZSDK package, which creates bootable SD card. Can you try with it?

    Best regards,
    Pavel

  • 0 in reply to Poh Boon Teo
    TI__Guru**** 170625 points

    Poh,

    Poh Boon Teo said:
    One deviation from the reference design is that I do not connect the WP pin but I do not think that is the problem.

    Have a look in the below thread, where we discuss the WP and CD pins:

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/277798/975863.aspx

    BR
    Pavel