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AM6421: First time processor boot-up and DDR4 testing queries

Nikhil Jadhav
Prodigy 70 points
Part Number: AM6421

Hello, we are using AM6421 series processor in one of our designs. For first time boot, we have few queries as listed below:

1) Is there any boot mode option available where any external memory or external peripheral is not involved?

2) While reading TRM (Technical reference manual) of AM6421, I came across "NO boot / Development boot". Do we need any external memory or peripheral with this mode to communicate with processor while booting?

3) We are using DDR4 in our design. Before first time processor boot-up, is there any way to test DDR separately, just to verify if schematic hardware is working fine?

4) Is there any booting mode option (Including "NO boot / Development boot"), where DDR is not involved?

Regards,

Nikhil Jadhav

  • +1
    TI__Guru 59371 points

    Hello Nikhil,

    1) You can use the UART bootmode to boot SBL/SPL from the UART itself assuming you have the UART working. This will remove the requirement of OSPI or eMMC.

    2) You will need JTAG interface on your board for DEVBOOT mode. If you are using HSFS device, which we recommend, NOBOOT is not possible.

    3) If you are using HSFS device, testing DDR is not straightforward. You may refer to the following thread which discusses testing DDR using JTAG via CCS GEL scripts for AM62x/AM62A

    SK-AM62B: AM62B EVM JTAG testing is mul-function? - Processors forum - Processors - TI E2E support forums

    4) For ROM booting SBL/SPL, you do not need DDR in any boot mode.

    Regards,

    Prashant

  • 0 in reply to Prashant Shivhare
    Prodigy 70 points

    Hi Prashant, Thanks for detailed answer. I still have below couple of doubts in point# 4.

    a) As far as I know, SBL/SPL is external boot loader which can be any external interface (eMMC, OSPI, USB, ethernet etc.) So, how can we use ROM to boot SBL/SPL? Is there any specific method to follow or we have to get it done from manufacturer before procuring the processor?

    b) Instead of ROM, if we use any external interface to boot SBL/SPL, DDR must be involved in a process. Right?

    Regards,

    Nikhil Jadhav

  • +1 in reply to Nikhil Jadhav
    TI__Guru 59371 points

    Hi Nikhil,

    There are two boot stages:

    1) ROM booting SBL/SPL

    SBL/SPL are always booted by ROM over any supported interface like UART, OSPI, USB DFU, eMMC, Ethernet, etc. For this stage of ROM booting SBL/SPL, you definitely do not need DDR and by booting over UART assuming UART is at least functional you can also avoid the requirement of working OSPI, eMMC, etc.

    For more details on ROM boot, you can go throught the TRM chapter 4 named Initialization.

    I happen to have a recording of booting SBL NULL over UART for AM62x. This is attached below:

    2) SBL/SPL booting next stage applications

    At this stage, you may or may not need DDR or external memories like eMMC, OSPI as per your application.

    Regards,

    Prashant

  • 0 in reply to Prashant Shivhare
    Prodigy 70 points

    Thank you. I think I understood the process now.

  • 0 in reply to Prashant Shivhare
    Prodigy 70 points

    Hi Prashant, one more query:

    We changed DDR part in our design. It is not same as EVM.

    In this case, do we need to change any device id/vendor id/any other change for new DDR part in SOC firmware?

    Regards,

    Nikhil Jadhav

  • +1 in reply to Nikhil Jadhav
    TI__Guru 59371 points

    Hi Nikhil,

    Yes, you would need to integrate the custom DDR configurations into the SDKs. If the DDR configurations are correct, the DDR drivers initializes the DDR at run time and the applications then will be able to use the DDR.

    Please check the DDR configuration tool at the below link. The tool generates different SDKs files based on the inputs provided in the GUI. The files generated then can be integrated as it is into the SDKs.

    https://dev.ti.com/sysconfig/#/start

    Regards,

    Prashant