Datasheet
TUSB1310A
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SLLSE32E –NOVEMBER 2010–REVISED JULY 2012
3.4.3 8b/10b Decode Errors
When the TUSB1310A detects an 8b/10b decode error, it will assert a SUB symbol in the data on the
RX_DATA where the bad byte occurred. In the same clock cycle that the SUB symbol is asserted on the
RX_DATA, the 8b/10b decode error code (100b) will be asserted on the RX_STATUS. 8b/10b Decoding
error has priority over all other receiver error codes and could mask out a disparity error occurring on the
other byte of data being clocked onto the RX_DATA with the SUB symbol.
Table 3-6. 8b/10b Decode Errors
RX_STATUS2-0 DETECTED ERROR LENGTH
Clock cycles during the ef fected byte is transferred on
100b 8B/10B Decode Error
RX_DATA15-0
3.4.4 Elastic Buffer Errors
When the elastic buffer overflows, data is lost during the reception of the data. The elastic buffer overflow
error code (101b) will be asserted on the RX_STATUS on the PCLK cycle the omitted data would have
been asserted. The data asserted on the RX_DATA is still valid data, the elastic buffer overflow error code
on the RX_STATUS just marks a discontinuity point in the data stream being received.
When the elastic buffer underflows, SUB symbols are inserted into the data stream on the RX_DATA to fill
the holes created by the gaps between valid data. For every PCLK cycle a SUB symbol is asserted on the
RX_DATA, an elastic buffer underflow error code (111b) is asserted on the RX_STATUS. In Nominal
Empty buffer mode, SKP ordered sets are transferred on RX_DATA and the underflow is not signaled.
Table 3-7. Elastic Buffer Errors
RX_STATUS2-0 DETECTED ERROR LENGTH
101b Elastic Buffer overflow Clock cycles the omitted data would have appeared
Clock cycles during the SUB symbol presence on
110b Elastic Buffer underflow.
RX_DATA15-0
3.4.5 Disparity Errors
When the TUSB1310A detects a disparity error, it will assert a disparity error code (111b) on the
RX_STATUS in the same PCLK cycle it asserts the erroneous data on the RX_DATA. The disparity code
does not discern which byte on the RX_DATA is the erroneous data.
Table 3-8. Disparity Errors
RX_STATUS2-0 DETECTED ERROR LENGTH
Clock cycles during the ef fected byte is transferred
111b Disparity Error
on RX_DATA15-0
3.5 Loopback
The TUSB1310A begins an internal loopback operation from SSRXP/SSRXN differential pairs to
SSTXP/SSTXN differential pairs when the TX_DETRX_LPBK is asserted while holding TX_ELECIDLE de-
asserted. The TUSB1310A will stop transmitting data to the SSTXP/SSTXN signaling pair from the
TX_DATA and begin transmitting on the SSTXP/SSTXN signaling pair the data received at the
SSRXP/SSRXN signaling pair. This data is not routed through the 8b/10b coding/encoding paths. While in
the loopback operation, the received data is still sent to the RX_DATA. The data sent to the RX_DATA is
routed through the 10b/8b decoder.
The TX_DETRX_LPBK de-assertion will terminate the loopback operation and return to transmitting
TX_DATA over the SSTXP/SSTXN signaling pair. The TUSB1310A only transitions out of loopback on
detection of LFPS signaling by transitioning to P2 state and starting the LFPS handshake.
Copyright © 2010–2012, Texas Instruments Incorporated FUNCTIONAL DESCRIPTION 21
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