PEB2256HT datasheet(71/490 Pages) INFINEON

71 / 490 page

FALC56 V1.2

PEB 2256

Functional Description E1

Data Sheet

2002-08-27

• Frame alignment between system frame and receive route frame

• Reporting and controlling of slips

Controlled by special signals generated by the receiver, the unipolar bit stream is

converted into bit-parallel data which is circularly written to the elastic buffer using

internally generated receive route clock (RCLK).

Reading of stored data is controlled by the system clock sourced by SCLKR or by the

receive jitter attenuator and the synchronization pulse (SYPR) together with the

programmed offset values for the receive time slot/clock slot counters. After conversion

into a serial data stream, the data is given out on port RDO. If the receive buffer is

bypassed programming of the time slot offset is disabled and data is clocked off with

RCLK instead of SCLKR.

In one frame or short buffer mode the delay through the receive buffer is reduced to an

average delay of 128 or 46 bits. In bypass mode the time slot assigner is disabled. In this

case SYPR programmed as input is ignored. Slips are performed in all buffer modes

except the bypass mode. After a slip is detected the read pointer is adjusted to one half

of the current buffer size.

The following table gives an overview of the receive buffer operating mode.

In single frame mode (SIC1.RBS), values of receive time slot offset (RC1/0) have to be

specified great enough to prevent too great approach of frame begin of line side and

frame begin of system side.

Figure 19 gives an idea of operation of the receive elastic buffer:

A slip condition is detected when the write pointer (W) and the read pointer (R) of the

memory are nearly coincident, i.e. the read pointer is within the slip limits (S +, S –). If a

Table 15

Receive Buffer Operating Modes (E1)

Buffer Size

(SIC1.RBS1/0)

TS Offset programming

(RC1/0) + SYPR = input

Slip performance

bypass

In bypass mode the clock provided on pin SCLKR is ignored. Clocking is done with RCLK.

disabled

recommended:

SYPR = output

short buffer

not recommended,

recommended:

SYPR = output

yes

1 frame

not recommended,

recommended:

SYPR = output

yes

2 frames

enabled

yes

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