AM335x sd card can not boot once in a while

Praveen Murthy

Other Parts Discussed in Thread: AM3354, TPD6E001

Hello,

We have designed our device using Sitara AM3354. this device boots with SD card, we have made 20 devices, some of the devices, occasionally refuses to boot MLO [say once in a week or so]. the debug uart continuous printing "C". This device will only boot after taking the SD card out and flashing the code once again.

Our boot configuration is AM335X_LCD_DATA[15.0] - 0100000010XX100100b - UART0, XIP W/Wait(Mux1),MMC0,NAND, snapshot of the schematics is attached in this mail for your reference:

I understand some has faced similar issue and same was fixed, link below:

http://e2e.ti.com/support/arm/sitara_arm/f/791/p/374806/1391266#pi239031349filter=answers&pi239031349scroll=true

Can you please advise what could be the reason for occasional boot failures ?

Regards,

Praveen

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi Praveen,

Do you have a serial resistor on the MMC0_CLK line? How long are the traces from processor to SD card connector? Do you have ESD protection on the MMC0 lines?

0 Praveen Murthy over 10 years ago in reply to Biser Gatchev-XID

Prodigy 60 points

Thanks for your swift reply.
22 ohms series resistance is added to MMC0_CLK line
Total Manhattan length of 2279 mils [58 mm] from 22 ohms resistor to SD card connector, Manhattan length from BGA ball to 22ohm resister is 272.29 MIL [7mm]
TPD6E001 ESD protection diode is used for all the MMC lines [MMC_CMD, MMC_CLK, MMC_Data[3:0].

0 Biser Gatchev-XID over 10 years ago in reply to Praveen Murthy

TI__Guru**** 393215 points

I can find no hardware reason for the malfunction you describe.

0 Biser Gatchev-XID over 10 years ago in reply to Biser Gatchev-XID

TI__Guru**** 393215 points

Just as an idea, have you tried connecting chassis GND to DGND?

0 Biser Gatchev-XID over 10 years ago in reply to Biser Gatchev-XID

TI__Guru**** 393215 points

And maybe add a couple of decoupling capacitors on VDDSHV4 close to the SD connector. 1x10uF + 1x0.1uF should be fine.

0 Praveen Murthy over 10 years ago in reply to Biser Gatchev-XID

Prodigy 60 points

Dear Biser,

Thanks for your inputs, ferrite bead 150OHM/800mA is used between chassis GND & DGND, currently 1x4.7uF + 1x0.1uF decoupling cap is used in design close to SD card connector power pin, will short the ferrite bead and add 1x10uF + 1x0.1uF decoupling cap.

Thanks & Regards,
Praveen

0 Biser Gatchev-XID over 10 years ago in reply to Praveen Murthy

TI__Guru**** 393215 points

I don't think these steps will be necessary, everything seems alright. Must be some software issue, but I'm afraid I can't help there.

0 Wolfgang Muees1 over 10 years ago

Genius 3685 points

R11 = 470K seems to be a very large value.
Try 10K instead.

Are you sure that the CPU XTAL is running when RESET is released at power-up? Can you add some reset-active-time?

0 Wolfgang Muees1 over 10 years ago

Genius 3685 points

On MMC0_D3, I have a PULLDOWN of 1MOhm. SD card will drive this line with a 50K pullup.

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AM335x sd card can not boot once in a while