Debug OSD335x-SM SD Card Boot

[Neeraj Dantu]

If you are having problems booting from a SD card on your system but you are able to confirm that the processor is has started (seeing “C” on the serial lines) then here are a few recommendations of things to try to find the root cause.

1. Check power rails especially SYS_VDD1_3P3V if that is what you are using to power the SD card interface. Make sure this voltage rail is stable when the board boots up.

2. Probe the SYSBOOT(LCD_DATAx) pins and verify that you have the right boot mode that puts the SD card interface in the boot order. If there is an interface that takes priority over the SD card interface, probe the data signals to make sure that the device is not getting stuck on trying to boot from another interface before it gets to the SD card. You can see the SYSBOOT configuration options in Table 26-7 of the AM335x Technical Reference Manual: https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf

3. Once you make sure that the boot order is correct, probe the SD card interface CLK and DATA0 lines to see if the device is probing the SD card for a bootable image. You should see a 50MHz clock on the CLK line and data on DATA0 line. Additionally, make sure that the card detect pin goes from HIGH to LOW after you insert the SD card.

4. Check if the image you are using is checking for an EEPROM ID that does not exist on your board. You can probe the EEPROM by connecting to the I2C0 interface from another board(You will have to make sure that there is no EEPROM on the board you are using to probe the failed board). Please take a look at the EEPROM application note here: OSD335x EEPROM During Boot to understand the role of EEPROM during boot.

    

5. Since you are able to see “CC” on UART, you can send SPL and U-Boot via UART to get to the U-Boot console and run commands that probe/test the SD card interface. Please see attached python script that can be used to do this. Once you execute the script with the SPL and U-Boot in the same folder, it should send over the SPL and U-Boot over UART. You can then open a minicom/picocom terminal and interact with the device on U-Boot command prompt.

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