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AM5728: setting the sysboot to 0b00

Robert Eschbach
Expert 6695 points
Part Number: AM5728

I have a question about the Sysboot Configuration of the AM5728 Sitara processor. According to the TRM, setting the sysboot[5:4] pins to 0b00 should enable “Peripheral Preferred Booting”; elsewhere in the TRM, it says that Peripheral Preferred Booting is usually used for booting from a communication interface, such as USB or UART. But according to Table 33-9 below, the “First Devices” for “Peripheral Preferred Booting” are USB and SD.

We have been trying to boot up our boards from a MicroSD card and have been unsuccessful with sysboot[5:4] set to 0b00, so I’m thinking that there is an error in Table 33-9; the “SD” options should actually be “UART”. Can you check on this for us?

 

If I am correct about an error in Table 33-9, then can you also confirm that we should be using the sysboot configuration circled below for “Memory Preferred Booting” (our goal is to use the MicroSD card to boot up the processor and then “transfer” the boot code to the QSPI memory for future bootups)?

  • 0
    TI__Mastermind 48033 points
    Robert Eschbach said:
    According to the TRM, setting the sysboot[5:4] pins to 0b00 should enable “Peripheral Preferred Booting”;

    This is not correct . The TRM does not say this, please see the full table from TRM

    The booting device order selected by ROM code depending on sysboot[5:0] pins. not just sysboot[5:4].

    Thanks.

  • 0
    Intellectual 290 points

    Praveen,

    I believe you are referring to an outdated revision of the TRM; the table you have included is from the revision dated October 2014, while the most recent revision is dated August 2019. In the latest revision, Table 33-9 clearly states that "Peripheral Preferred Booting" types are selected when sysboot[5:4] = 0b00 and "Memory Preferred Booting" types are selected when sysboot[5:4] = 0b10; the sysboot[3:0] configuration determines the boot device order for the selected boot type.

    In Section 33.3.1.1 of the TRM, it says that peripheral booting "polls a selected communication interface such as UART or USB". That is why I was asking about a possible error in Table 33-9: should the 4 boot device orders with "SD" listed as the First Device actually list "UART" as the first device?

    On our new PCB assemblies, we have sysboot[5:4] = 0b00 and sysboot[3:0] = 0b0110. According to Table 33-9, we should try to boot from SD first and then QSPI_1 second. But our boards are not booting up from our MicroSD card, which is why I theorized that Table 33-9 was wrong and we should actually be using sysboot[5:4] = 0b10 and sysboot[3:0] = 0b0110.

  • 0 in reply to Sean Heffernan1
    TI__Mastermind 48033 points

    OK, I have referred an older TRM snippet in my previous response, but still my comment overall is still valid.

    We did check with our BootROM team and they confirmed that the setting in the TRM are correct. Though the section of the table says "Peripheral Preferred Booting", for the sysboot [5:0] = 0b000110 , the first boot device is SD and second boot device is OSPI_1

    Thanks.