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PEB 2255
FALC-LH V1.3
Functional Description T1/J1
Data Sheet
116
2000-07
a receive slip occurred
5.1.12.3
CAS Bit-robbing (T1/J1,
μ
P access mode)
The signaling information is carried in the LSB of every sixth frame for each time slot.
The signaling controller samples the bit stream on the receive line side. Receive
signaling data is stored in the registers RS1-12.
To relieve the
μ
P load from always reading the complete RS1-12 buffer every 3 ms the
FALC
-LH notifies the
μ
P via interrupt ISR0.RSC only when signaling changes from one
multiframe to the next.
5.1.12.4
The FALC
-LH supports the DL-channel protocol for ESF format according to ANSI
T1.
4
03 specification or according to AT
&
T TR5
4
016. The HDLC- and Bit Oriented
Message (BOM)-Receiver may be switched ON/OFF independently. If the FALC
-LH is
used for HDLC formats only, the BOM receiver has to be switched off. If HDLC- and
BOM-receiver has been switched on (MODE.HRAC/BRAC), an automatic switching
between HDLC and BOM mode is enabled. If eight or more consecutive ones are
detected, the BOM mode is entered.
U
pon detection of a flag in the data stream, the
FALC
-LH switches back to HDLC-mode. In BOM-mode, the following byte format is
assumed (the left most bit is received first): 111111110xxxxxx0
Two different BOM reception modes can be programmed (CCR1.BRM).
Bit Oriented Messages in ESF-DL Channel (T1/J1)
5.1.12.5
Data Link Access in F72 Format (T1/J1)
The DL-channel protocol is supported as follows:
- access is done on a multiframe basis via registers RDL1-3,
- the DL bit information from frame 26 to 72 is stored in the Receive FIFO of the signaling
controller.
5.2
System Interface in T1/J1 Mode
The interface to the receive system highway is realized by two data buses, one for the
data RDO and one for the signaling data RSIG. The receive highway is clocked via pin
SCL
K
R, while the interface to the transmit system highway is independently clocked via
pin SCL
KX
. The frequency of these working clocks and the data rate for the receive and
transmit system interface is programmable by SIC1.SRSC and SIC1.S
X
SC. Transmit
and receive clock frequencies have to be the same. Selectable system clock and data
rates and their valid combinations are shown in the table below.