PEB22554 SIEMENS [Siemens Semiconductor Group], PEB22554 Datasheet - Page 222

• Manufacturer Part Number: PEB22554
• Description: ICs for Communications
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

• 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, time-slot-serial 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 Synchronous Pulse (SYPR) in conjunction 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 via 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.
The 24 received time-slots are translated into the 32 system time-slots in two different
channel translation modes (FMR1.CTM). Unequipped time-slots will be set to ‘FF
Refer to table 17.
In one frame or short buffer mode the delay through the receive buffer is reduced to an
average delay of 96 or 48 bits. In bypass mode the time-slot assigner is disabled. In this
case SYPR programmed as input is ignored. Slips will be 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 .
1) In bypass mode the clock provided on pin SCLKR is ignored. Clocking is done with RCLK.
Figure 49 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
slip condition is detected, a negative slip (one frame or one half of the current buffer size
Semiconductor Group
Buffer Size
(SIC1.RBS1/0)
bypass
short buffer
1 frame
2 frames
1)
TS Offset program.
(RC1/0) + SYPR = input
disabled
not recommended,
recom. SYPR = output
not recommended,
recom. SYPR = output
enabled
222
Functional Description T1 / J1
Slip perform.
no
yes
yes
yes
PEB 22554
09.98
H
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