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REG boot time instances for AM335x

Shradhanand Mahendraker
Intellectual 580 points

Hi,

Could anyone please clarify me this point?

when Am335x is reset, we could see the boot happens according to boot device list (i.e sysboot configuration). as we have many boot configurations/boot instances like usb0, uart/xmodem which work immediately at reset time. but for custom boards, we do have usb and other instances connected with different balls which HW engineer's design based on their convenience... is it that default pins are used at boot time for any board and when it gets into user mode, the instances/communications work according to custom board pins/balls?

This doubt i got because i want to use USB boot for my device/custom board. As per my schematic i have some configuration to use for USB, i have seen that boot rom activates usb0 instance for this.... so how does this work? do i need to configure as per my schematic even for boot rom instance like ex: usb0.

Regards,

Shradhanand

  • 0
    TI__Intellectual 1640 points

    Hi Shradhanand ,

    The ROM code expects that user will use the same instance for booting as mentioned in the TRM. As an example

    if you have chosen USB as your bootmode, then  your custom board schematic needs to use USB0 as the controller instance to be connected to the PC. Wiring up USB1 would not work.

  • 0 in reply to Vineeth Balan
    Intellectual 580 points

    Hi Vineeth,

    Thanks for the quick reply. But my question is that.. when people design their custom boards. they have their own set of pins for devices. for example my custom board has these pin configuration for USB.

    ZCZ BALL NUMBER

    PIN NAME

    SIGNAL NAME

    N18

    USB0_DM

    USB0_DM

    N17

    USB0_DP

    USB0_DP

    P16

    USB0_ID

    USB0_ID

    P15

    USB0_VBUS

    USB0_VBUS

    F16

    USB0_DRVVBUS

    USB0_DRVVBUS

    A15

    XDMA_EVENT_INTR0

    AM335x_XDMA_EVENT_INTR0

    D14

    XDMA_EVENT_INTR1

    AM335x_XDMA_EVENT_INTR1

    Now my question is that do i need to use pin configurations for USB0 which are provided by my HW designer? Because when we go for sysboot for usb boot, sitara operates directly from boot rom. so i want to clarify this doubt of mine.

    Regards,

    Shradhanand