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J721EXSOMXEVM: Boot failure with multiple SDK and J721SOM Rev A (PROC078A) board.

Yannik Muendler
Prodigy 305 points
Part Number: J721EXSOMXEVM
Other Parts Discussed in Thread: TCA6424A

Hi,

We have multiple J721 SoM Board and custom baseboards.

With the latest Revision PROC078A we noticed different behaviors. On the Standard Baseboard (J721EXCP01EVM) all Revisions are working as expected.

Also the older (PROC078E7A and PROC078E8A) revisions are working without any problems with our baseboard.

We tried from SDK 07.03. up to SDK 08.01.(what is shipped with the SoM board)

Most of the time on the first start up the latest revision of the SoM board is booting completely on "our" baseboard.
But hard resetting or via command: "reboot" the boot process will stop at a random time.

At that "stopped" state, all PMIC A and PMIC B output voltages are off.

I also tried to lower the DDR Frequency like in that post: e2e.ti.com/.../faq-tda4vm-on-7-3-8-0-sdk-how-to-reduce-ddr-speed-to-3733-mts

Any further advise / approach?

Thank you

  • 0
    TI__Prodigy 305 points

    We were able to read the PMIC registers and noticed following:

    Inside PMIC-B (U29) following register Bit were 1:

    PMIC-B INT_FSM_ERR BIT 3 SOC_PWR_ERR_INT 0x1
    INT_LDO3_4 BIT 0 LDO3_Overvoltage Event detected 0x1

    On "our" baseboard we used the VDD_IO_1V8_REG (VSYS_IO_1V8) for some Level shifters.

    We are now measuring the 1.8V and measuring a short peak of 1.97V

  • 0 in reply to Yannik Muendler
    TI__Prodigy 305 points

    We hat an TCA6424A GPIO Expander on the  VSYS_IO_1V8 rail. There an output had an Level Shifter with an Pull-up to VSYS_IO_3V3. Changing that Pull-up to VSYS_IO_1V8 solved the boot issue