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OMAP-L138: Can I show down the USB IN token after NAK in bulk transfer?

Yee Yong Teo
Expert 4335 points
Part Number: OMAP-L138
Other Parts Discussed in Thread: OMAPL138

Hi,

OMAP-L138 USB host transmit IN token every 5us after received NAK from device in bulk transfer mode. Can I slow down the IN token transmit?

Thanks.

- YY

  • 0
    TI__Guru 65405 points
    Hi YY,

    I've forwarded this to the USB experts. Their feedback should be posted here.

    BR
    Tsvetolin Shulev
  • 0 in reply to Cvetolin Shulev-XID
    TI__Guru** 116170 points
    Posting response from our TI USB expert regarding this issue

    If a NAK is received, the OMAPL138 tries again and continues to try until either the transaction is successful or the NAKLimit is set. The OMAPL138 then generates the appropriate endpoint interrupt, whereupon the host should read the corresponding register to determine whether the RxPktRdy, RxStall, Error or NAK Timeout bit is set and act accordingly. If the NAK Timeout bit is set, the OMAPL138 can be directed either to continue trying this transaction until it times out again by clearing the NAK Timeout bit or to abort the transaction by clearing ReqPkt before clearing the NAK Timeout bit.

    One concern I have is the continue set of NAK Timeout bit which requires the host continues to set/clear this bit.


    there is similar discussion on going on this thread :
    e2e.ti.com/.../2162678