TLK10232 datasheet(32/102 Pages) TI

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INA0P/N

Channel A

Low

Speed

Side

SERDES

TX FIFO

Pattern

Generator

High

Speed

Side

SERDES

INA1P/N

INA2P/N

INA3P/N

OUTA0P/N

OUTA1P/N

OUTA2P/N

OUTA3P/N

RX FIFO

Pattern

Verifier

LS PRBS

Verifier

LS PRBS

Generator

HS PRBS

Generator

HS PRBS

Verifier

Latency

Counter

Start

Counter

Stop

Counter

Transmit Data Path Covered

Receive Data Path Covered

Start

Counter

Stop

Counter

HSTXAP

HSRXAP

TLK10232

SLLSEE1 – MAY 2013

www.ti.com

7.4

Latency Measurement Function (General Purpose SerDes Mode)

The TLK10232 includes a latency measurement function to support CPRI and OBSAI type applications.

There are two start and two stop locations for the latency counter as shown in Figure 7-2 for Channel A.

The start and stop locations are selectable through MDIO register bits. The elapsed time from a comma

detected at an assigned counter start location of a particular channel to a comma detected at an assigned

counter stop location of the same channel is measured and reported through the MDIO interface. The

function operates on one channel at a time. The following three control characters (containing commas)

are monitored:

1. K28.1 (control = 1, data = 0x3C)

2. K28.5 (control = 1, data = 0xBC)

3. K28.7 (control = 1, data = 0xFC).

The first comma found at the assigned counter start location will start up the latency counter. The first

comma detected at the assigned counter stop location will stop the latency counter. The 20-bit latency

counter result of this measurement is readable through the MDIO interface. The accuracy of the

measurement is a function of the serial bit rate at which the channel being measured is operating. The

exceeds the depth of the counter. Only one measurement value is stored internally until the 20-bit results

counter is read. The counter will return zero in cases where a transmit comma was never detected

(indicating the results counter never began counting). In addition, the stopwatch counter can be configured

to be started or stopped manually based on the state of the PRTAD0 pin (see MDIO register map for

details).

Figure 7-2. Location of TX and RX Comma Character Detection (Only Channel A Shown)

In high speed side SERDES full rate mode, the latency measurement function runs off of an internal clock

which is equal to the frequency of the transmit serial bit rate divided by 8. In half rate mode, the latency

measurement function runs off of an internal clock which is equal to the serial bit rate divided by 4. In

quarter rate mode, the latency measurement function runs off of an internal clock which is equal to the

serial bit rate divided by 2. In eighth rate mode, the latency measurement function runs off of a clock

which is equal to the serial bit rate.

ADDITIONAL FEATURES

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