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Question about AM335x USB Bulk Transfer

g.f.
Guru 15520 points
Other Parts Discussed in Thread: AM3352

Hi,

I have a question about AM335x USB2.0.

My customer are using AM3352.
At their customer board AM3352 is USB host and they are trying bulk transfer.

USB device are sending 1024 byte to AM3352 by bulk transfer
and it seem they are having problem.
My understanding is that USB2.0 spec support up to 512 byte(max) bulk transfer,
so that AM3352 could not get 1024 byte from USB device and cause unexpected result.
Is it correct?

Or if they set the value of wMaxPacketSize, TXMAXP and RXMAXP to 1024,
is AM335x available to get 1024 byte by bulk transfer?

By the way, I can't find the TXMAXP and RXMAXP register description in TRM.
Is there any information?

best regards,
g.f.

  • 0
    TI__Guru**** 393215 points

    Hi g.f.

    AM335X TRM Rev. K, section 16.3.8.1.2.1.2 states:

    "In the general case, the packet size must not exceed the size specified by the lower 11 bits of the TXMAXP register. This part of the register defines the payload (packet size) for transfers over the USB and is required by the USB Specification to be either 8, 16, 32, 64 (Full-Speed or High-Speed) or 512 bytes (High-Speed only)."

  • 0 in reply to Biser Gatchev-XID
    Guru 15520 points

    Hi Biser,

    Thank you for the reply.

    In that section, it's only written about the TXMAXP( "Bulk IN Operation: Peripheral Mode").
    Is RXMAXP(Bulk OUT) also required to configure base on USB Specification?
    And how about the packet size value of TXMAXP and RXMAXP when in Host Mode of Bulk transfer?

    By the way, where are TXMAXP and RXMAXP registers mapped to?
    I can't find in the datasheet and TRM.

    best regards,
    g.f.

  • 0 in reply to g.f.
    TI__Guru**** 393215 points

    According to USB2.0 specification 512 bytes is the maximum packet size regardless of the transfer direction, and this is valid only for USB high-speed mode. For full-speed mode the  maximum packet size can be 8, 16, 32 or 64 bytes.

    About the register descriptions, please contact your nearest TI representative for more information.

  • 0 in reply to Biser Gatchev-XID
    Guru 15520 points

    Hi Biser,

    Thank you for the reply.

    I understood about the packet size.
    Thank you so much.

    I will contact to my local TI FAE for the register description.

    best regards,
    g.f.