![](http://datasheet.mmic.net.cn/330000/IDT82P2281_datasheet_16415955/IDT82P2281_81.png)
IDT82P2281
SINGLE T1/E1/J1 LONG HAUL / SHORT HAUL TRANSCEIVER
70
October 7, 2003
3.20.1.2
E1 Mode
In E1 mode, the Frame Generator can generate Basic Frame,
CRC-4 Multi-Frame and Channel Associated Signaling (CAS) Multi-
Frame. The Frame Generator can also transmit alarm indication signal
when special conditions occurs in the received data stream. Interna-
tional bits, National bits and Extra bits replacements and data inversions
are all supported in the Frame Generator.
The generation of the Basic frame, CRC Multi-Frame and Channel
Associated Signaling (CAS) Multi-Frame are controlled by the FDIS bit,
the GENCRC bit, the CRCM bit and the SIGEN bit. Refer to Table 47 for
details.
When the Basic frame is generated, the Frame Alignment
Sequence (FAS) (‘0011011’) will replace the Bit 2 ~ Bit 8 of TS0 of each
even frame; the NFAS bit (‘1’) will replace the Bit 2 of TS0 of each odd
frame. If the FAS1INV bit is set, one FAS bit will be inverted; if the
FASALLINV bit is set, all 7 FAS bits will be inverted; if the NFASINV bit is
set, the NFAS bit will be inverted.
When the Basic frame is generated, if the SiDIS bit is ‘0’, the value
set in the Si[1] and Si[0] bits will replace the International bit (Bit 1) of
FAS frame and NFAS frame respectively.
When the Basic frame is generated, the Remote Alarm Indication
(RAI) can be transmitted as logic 1 in the A bit position. It is transmitted
manually when the REMAIS bit is ‘1’. It can also be transmitted automat-
ically when the AUTOYELLOW bit is set to ‘1’. In this case, the RAI
transmission criteria are selected by the G706RAI bit.
When the Basic frame is generated, the setting in the SaX[1] bit will
be transmitted in the Sa bit position if enabled by the corresponding
SaXEN bit (‘X’ is from 4 to 8).
The CRC Multi-Frame is generated on the base of the Basic frame
generation. When it is generated, the CRC Multi-Frame alignment pat-
tern (‘001011’) will replace the Bit 1 of TS0 of the first 6 odd frames; the
calculated 4-bit CRC of the previous Sub-Multi-Frame will be inserted in
the CRC-bit positions of the current Sub-Multi-Frame. The CRC-bit posi-
tion is the Bit 1 of TS0 of each even frame. Refer to Table 18 for the
CRC Multi-Frame structure. If the CRCPINV bit is set, all 6 CRC Multi-
Frame alignment bits will be inverted; if the CRCINV bit is set, all 4 cal-
culated CRC bits will be inverted.
When the CRC Multi-Frame is generated, since 14 International bit
positions have been occupied by the CRC Multi-Frame alignment pat-
tern and CRC-4 checking bits, the remaining 2 International bit positions
are inserted by the E bits. The control over the E bits is illustrated in
Table 48.
When the CRC Multi-Frame is generated, the setting in the
SaX[1:4] bits will be transmitted in the Sa bit position if enabled by the
corresponding SaXEN bit (‘X’ is from 4 to 8).
The Channel Associated Signaling (CAS) Multi-Frame is generated
on the base of the Basic frame generation. When it is generated, the
Signaling Multi-Frame alignment pattern (‘0000’) will replace the high
nibble (Bit 1 ~ Bit 4) of TS16 of every 16 Basic frames. If the CASPINV
bit is set, all 4 Signaling Multi-Frame alignment bits will be inverted.
When the Signaling Multi-Frame is generated, if the XDIS bit is ‘0’,
the value set in the FGEN Extra register will be inserted into the Extra
bits (the Bit 5, 7 & 8 of TS16 of Frame 0 of the Signaling Multi-Frame).
When the Signaling Multi-Frame is generated, the value in the
MFAIS bit will be continuously transmitted in the Y bit position (the Bit 6
of TS16 of Frame 0 of the Signaling Multi-Frame).
When the Signaling Multi-Frame is generated, all the bits in TS16
can be overwritten by all ‘Zero’s or all ’One’s by setting the TS16LOS bit
or the TS16AIS bit respectively. The all zeros overwritten takes a higher
priority.
When the Modified CRC Multi-Frame is generated, only the Sa bit
position and the calculated CRC-4 bit position can be changed. All the
other bits are transparently transmitted unless all ’One’s or all ‘Zero’s are
transmitted (refer to Chapter 3.20.6 All ‘Zero’s & All ‘One’s).
The frame can only be generated on the base of the FDIS bit being
‘0’. If the FDIS bit is set to ‘1’, the data received from the Transmit Pay-
load Control will be transmitted transparently to the HDLC Transmitter.
Table 47: E1 Frame Generation
Desired Frame Type
FDIS GENCRC CRCM SIGEN
Basic Frame
0
0
0
0
0
0
0
1
1
1
0
1
X
0
0
1
X
0
X
X
X
X
1
1
CRC Multi-Frame
Modified CRC Multi-Frame
Channel Associated Signaling (CAS) Multi-
Frame
Table 48: Control Over E Bits
FEBEDIS OOCMFV
SiDIS
E Bits Insertion
0
0
X
A single zero is inserted into the E bit when a CRC-4 Error event is detected in the receive path. (the E1 bit corresponds to SMFI
and the E2 bit corresponds to SMFII)
The value in the Si[1] bit is inserted into the E1 bit position. The value in the Si[0] bit is inserted into the E2 bit position.
The value in the Si[1] bit is inserted into the E1 bit position. The value in the Si[0] bit is inserted into the E2 bit position.
The E bit positions are unchanged.
0
1
1
1
X
X
X
0
1