W6691CD WINBOND [Winbond], W6691CD Datasheet - Page 44

• Manufacturer Part Number: W6691CD
• Description: ISDN S/T Interface Transceiver
• Manufacturer: WINBOND [Winbond]

Control field bits
I frame
S frame
U frame
7.5.1 D Channel Message Transfer Modes
The D channel HDLC controller operates in transparent mode.
Chracteristics:
Note. The LAPD protocol uses the CRC_ITU-T for Frame Check Sequence. The polynominal is X
+ 1.
values, SAP1-2 and TEI1-2, plus two fixed values for group SAPI and TEI, SAPG and TEIG. The SAPG equals
02H(C/R=1) or 00H(C/R=0) which corresponds to SAPI = 0. The TEIG equals FFH which corresponds to TEI =
127. Incoming frame with 1
TEIG) will be stored in the receive FIFO, with flag and FCS fields being discarded and stuffed bits being
removed.
For address recognition, the W6691 provides four programmable registers for individual SAPI and TEI
-
-
-
-
-
Receive frame address recognition
Address comparison maskable bit-by-bit
Flag generation / deletion
Zero bit insertion/ deletion
Frame Check Sequence (FCS) generation/ check with CRC_ITU-T
M
7
0
M
st
6
0
address octet= (SAP1 or SAP2 or SAPG) and 2
M
5
0
N(S)
P/F
1st octet
4
0
M
S
3
M
S
2
44
1
0
1
0
0
1
1
7
6
Preliminary W6691
nd
Publication Release Date: Sep 2001
address octet= (TEI1 or TEI2 or
5
N(R)
N(R)
2nd octet
4
3
2
16
Revision 1.1
+ X
1
12
+ X
P/F
P/F
0
5