
QuadFALC
TM
PEF 22554 E
Functional Description E1
Data Sheet
132
Rev. 1.2, 2006-01-26
The following table gives an overview of the receive buffer operating mode.
In single frame mode (SIC1.RBS), values of receive time slot offset (RC(1:0)) have to be specified large enough
to prevent approach of frame begin on the line side and frame begin on the system side.
Figure 42 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 is skipped) or
a positive slip (one frame or one half of the current buffer size is read out twice) is performed at the system
interface, depending on the difference between RCLK and the current working clock of the receive backplane
interface. I.e. on the position of pointer R and W within the memory. A positive/negative slip is indicated in the
interrupt status bits ISR3.RSP and ISR3.RSN.
Figure 42
The Receive Elastic Buffer as Circularly Organized Memory
4.2
Transmit Path (E1)
An overview of the transmit path of one channel of the QuadFALC
special E1 functionalities are described in this chapter.
Table 33
Receive Buffer Operating Modes (E1)
Buffer Size
(SIC1.RBS(1:0))
TS Offset Programming
(RC(1:0)) + SYPR = input
Slip Performance
Bypass
1)
1) In bypass mode the clock provided on pin SCLKR is ignored. Clocking is done with RCLK.
Disabled
Recommended: SYPR = output (usage
of the RFM with CMR2.IRSP = 0
B)
No
Short buffer
Not recommended,
Recommended: SYPR = output (usage
of the RFM with CMR2.IRSP = 0
B)
Yes
1 frame
Yes
2 frames
Enabled
Yes
Limits for Slip Detection (mode dependent)
Read Pointer (System Clock controlled)
Write Pointer (Route Clock controlled)
R’
S+, S-
R
:
W:
Frame 2 Time Slots
S-
R
Frame 1 Time Slots
Moment of Slip Detection
ITD10952
W
S+
Slip