am3352 - booting from sd card does not always succeed

Krzysztof Stasch

Other Parts Discussed in Thread: AM3352

Hi, I have build a custom board with am3352. I am booting the board from sd card of size 8Gb connected to mmc1. Now I have a weird problem, that is the board boots only every second time. When I power on the board for the first time the board does not boot from the sd card, on UART0 I see CCCC so the am3352 tries to boot from uart, the boot source after mmc1.

Now I power off and on again and the board boots from the sd card and everything works fine, linux starts and there are no problems with the sd card. I tried to increase reset time up to 200ms but this does not help. The sd card is on mmc1, there are 10k pullups connected to mmc1-DAT3 and mmc1-CMD lines to prevent that the card enters SPI mode.

Anybody knows what could be wrong?

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi Krzysztof,

Have you tried with different SD cards? For AM335X MMC0 is the recommended interface for SD card boot.

0 Brad Griffis over 10 years ago

TI__Guru*** 125430 points

Can you connect with JTAG and run this script after the first failed boot:

http://git.ti.com/am335x-dss-scripts/am335x-dss-scripts/blobs/master/am335x-boot.dss

The directions would be essentially the same as what's mentioned here:

http://processors.wiki.ti.com/index.php/AM335x_Clock_Tree_Tool#Importing_Data_from_Actual_Hardware

Please attach the generated file to your reply. Hopefully it will give some insight into what's happening.

0 Krzysztof Stasch over 10 years ago in reply to Brad Griffis

Prodigy 80 points

The trace vectors show correct values. I have noticed that when the board is connected to a usb port of a pc this boot problem does not appear. The usb on the am3352 is configured in device mode. One difference more that I have noticed when the board is connected to the pc usb port is that without the sd card the letters CCC appear on terminal less frequently than when the board is powered from external power supply. It seems that the connection to the pc usb port slows down the boot loop in the ROM code of the am3352 and mitigates the problem.

Regards

0 Brad Griffis over 10 years ago in reply to Krzysztof Stasch

TI__Guru*** 125430 points

Can you attach the file from the script? I wrote a script in order to make it easy for you to collect all the info I need to (hopefully!) debug your issue. You didn't post the output though, so there's not much further insight I can provide.

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am3352 - booting from sd card does not always succeed