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AM437x SPI boot time issue

Wayne Kuo
Intellectual 870 points

Other Parts Discussed in Thread: AM4376

Hi there,

 

Our customer has a SPI boot time issue.

Device: customer board with AM4376

SDK: Processor SDK 1.00.00.03

They want to boot their board from SD card and use SPI ROM for backup boot device.

It seems AM437x only have boot sequence 10010b can match this require in AM437x TRM (Ver. D).

However, customer use this boot sequence to boot from SPI, it takes 25 sec from power on to loading MLO.

 

We have checked the following items:

1. Use boot sequence 01001b (SPI only), it boot up immediately.

    We think SPI boot process is not the reason of this issue.

2. We checked the USB setting as follow (Following TI Taiwan FAE’s suggestion) to make sure boot process skip loading data from USB device.

        a. Making sure USB0 is not connected to PC as slave. No VBUS present if USB0 is host.

        b. Making sure USB1 is not connected to USB device which I assume it is host.

    After we check the above status, it does not help to reduce SPI boot time.

 

We got another suggestion is make a switch on SYSBOOT4 pin to control boot sequence (just like Beaglebone Black).

However, customer think this workaround might cause some inconvenient when maintain produce, so it’s not a potion right now.

 

Is there any suggestion for this issue?

Any information/suggestion would be appreciated.

 

Thank you and Regards,

Wayne Kuo

  • 0
    TI__Guru**** 393215 points
    Hi Wayne,

    The delay is caused by USB_CL boot mode. Section 5.2.7.5.1 of the AM437X TRM Rev. D states: "USB cable should be plugged in within 20 sec of powering up the device."
  • 0 in reply to Biser Gatchev-XID
    Intellectual 870 points
    Hi Biser,

    Thanks for the instant reply.
    We saw this information before.
    AM437x TRM Ver.D Section 5.2.7.5.2 says:
    "The ROM Code continues with the USB procedure only if the USB cable is detected present (that is,
    VBUS is detected at transceiver level and communicated as such through the UTMI traffic). If not, the
    initialization procedure is aborted."
    That means if we remove VBUS signal while booting then ROM code will skip the USB_CL initialization procedure and no need to wait 20 sec, right?
    Customer has removed the VBUS, but no luuck it still cost 25 sec to boot from SPI.

    Thank you and Regards,
    Wayne Kuo
  • 0 in reply to Wayne Kuo
    TI__Guru**** 393215 points
    Yes, this is correct, but the cable detection timeout is still 20 sec.