Advisory 1.1.12 — USB (Device Mode): Calculated CRC Value Does Not Match Host CRC Value

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Case 2: Isochronous Transfers (High- and Full-Speed): For Isochronous Transfers

operating in either High- or Full-Speed modes, upon receiving a CRC error, the USB

controller flags the device application S/W that a CRC error existed but will retain the

received data within the FIFO as well as capture the received data packet size value

minus one byte from the actual data packet size. Since the magnitude of the actual

timing violated due to the synchronization problem is only in pico-seconds, the entire

data sent from the Host is routed into the USB device receive FIFO (i.e., even though

the received data counter is one byte less, the full data packet is available for the USB

driver) and the USB driver should ignore the received CRC error and read one more

additional byte from the receive FIFO. This one-byte counter difference is transparent to

the Host H/W and S/W.

Due to the rare occurrence of this issue and its very minimal impact on applications,

there are no plans to correct this issue in future silicon revisions.

TMS320DM335 Digital Media System-on-Chip (DMSoC)

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SPRZ287A – July 2008 – Revised October 2008

Silicon Revision 1.1

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