TUSB1310

SLLSE16B – DECEMBER 2009 – REVISED JUNE 2010

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Table 3-3. PIPE Control Pin Matrix

POWER STATE

TX_DETRX_LPBK

TX_ELECIDLE

DESCRIPTION

0

0

Transmitting data on TX_DATA

0

1

Not transmitting and is in electrical idle.

P0

1

0

Goes into loopback mode

1

1

Transmits LFPS signaling

0

Transmits LFPS signaling

P1

Don't care

1

Not transmitting and is in electrical idle.

Don't care

0

Transmits LFPS signaling

P2

0

1

Idle

1

1

Does a receiver detection operation

0

Transmits LFPS signaling

P3

Don't care

1

Does a receiver detection operation

3.4

Receiver Status

The TUSB1310 has an elastic buffer for clock tolerance compensation, the link partner detection, and

some received data error detections. The receive data status from SSRXP/SSRXN differential pair

presents on RX_STATUS2-0. If an error occurs during a SKP ordered set, the error signaling has

precedence. If more than one error occurs on a received byte, the errors have the priority below.

1. 8B/10B decode error

2. Elastic buffer overflow

3. Elastic buffer underflow (can not occur in nominal empty buffer model)

4. Disparity error

3.4.1

Clock Tolerance Compensation

The receiver contains an elastic buffer used to compensate for differences in frequencies between bit

rates at the two ends of a link. The elastic buffer must be capable of holding enough symbols to handle

worst case differences in frequency and worst case intervals between SKP ordered sets. A SKP order set

is a set of symbols transmitted as a group. The SKP ordered sets allows the receiver to adjust the data

stream being received to prevent the elastic buffer from either overflowing or under-flowing due to any

clock tolerance differences.

The TUSB1310 supports two models, nominal half full buffer model and nominal empty buffer mode. For

the nominal half full buffer model, the TUSB1310 monitors the receive data stream. When a Skip ordered

set is received, the TUSB1310 adds or removes one SKP order set from each SKP to manage its elastic

buffer to keep the buffer as close to half full as possible. Only full SKP ordered sets are added or

removed. When a SKP order set is added, the TUSB1310 asserts an “Add SKP” code (001b) on the

RX_STATUS for one clock cycle. When a SKP order set is removed, the RX_STATUS is has a “Remove

SHP” code (010b).

For the nominal empty buffer model the TUSB1310 attempts to keep the elasticity buffer as close to empty

as possible. When no SKP ordered sets have been received, the TUSB1310 will be required to insert SKP

ordered sets into the received data stream.

Table 3-4. RX_STATUS - SKP

RX_STATUS2-0

SKP ADDITION or REMOVAL

LENGTH

001b

1 SKP ordered set added

One clock cycle

010b

1 SKP ordered set removed

20

FUNCTIONAL DESCRIPTION

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Product Folder Link(s): TUSB1310