TUSB1310

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SLLSE16C – DECEMBER 2009 – REVISED AUGUST 2010

Table 3-6. 8b/10b Decode Errors

RX_STATUS2-0

DETECTED ERROR

LENGTH

Clock cycles during the effected byte is

100b

8B/10B decode error

transferred on 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, EDB (0xFE) 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 EDB 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

Clock cycles the omitted data would have

101b

Elastic buffer overflow

appeared

Clock cycles during the EDB symbol

110b

Elastic buffer underflow

presence on RX_DATA15-0

3.4.5

Disparity Errors

When the TUSB1310 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

111b

Disparity error

transferred on RX_DATA15-0

3.5

Loopback

The TUSB1310 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 TUSB1310 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 TUSB1310 only transitions out of loopback on

detection of LFPS signaling by transitioning to P2 state and starting the LFPS handshake.

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FUNCTIONAL DESCRIPTION

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