W6694CD WINBOND [Winbond], W6694CD Datasheet - Page 15

• Manufacturer Part Number: W6694CD
• Description: USB Bus ISDN S/T-Controller
• Manufacturer: WINBOND [Winbond]

into XFIFO. The continuous FFh will later be transmitted to corresponding B channel of ISDN
interface. This Isochronous-OUT packet error will be reported to host, by setting bit ISOE of
Isochronous-IN packet to 1. D channel FIFO will recognize and only accept data within HDLC frame
(including opening and closing flag), all other data outside HDLC frame are ignored and not stored in
FIFO. B channel FIFO accept any data after it is enabled.
Note: Because B1 and B2 channel data are of the same length (B_LEN), both channels should be reset/enabled at the same
The packet format of Isochronous-OUT is as below:
D_LEN1-0
These bits indicate the data length of the subsequent data for D channel. The typical value is 1 to 3, if
D channel message is sending; or 0 if no message to send. Once the opening flag of D channel
message is sent, W6694 will move the data in D-XFIFO to S interface at the rate of 16K bps. The
software must carefully assign proper length for each packet, otherwise a D-XFIFO under-run or
overflow condition may occur. The only valid data are HDLC frame, including opening and closing
flag (7Eh), and bit-stuffed data in between. Note that software should transmit the first data byte as
opening flag in byte (8-bits) boundary. Due to the nature of HDLC framing, the closing flag may not
be in byte-boundary. Software should stuff the remaining bit positions (if any) with binary ‘1’, to fill the
last byte, unless the last byte is 7Eh.
D_D
These are D channel data space, which always occupy 3 bytes in the packet. Software should put
actual data length in D_LEN. If the data length D_LEN is less then 3, the remaining data bytes should
be all FFh.
B_LEN3-0
These bits indicate the data length of subsequent data for each B channel. Once the B-XFIFO is
enabled (CMDR2:BnXEN), the length should be from 7 to 9 bytes inclusively, otherwise a transmit
FIFO under run or overflow condition may occur. If there is no data for B1/B2 channel, the length can
be 0. Note that the two B channels have same data length, but can be reset and enabled separately.
Bit 7
ATA
time.
6
D Channel Data Length
D Channel Data
B Channel Data Length
5
D_DATA (2
D_DATA (1
D_DATA (3
4
B1_DATA
B2_DATA
...
...
B_LEN3
nd
st
rd
byte)
byte)
3
byte)
- 15 -
B_LEN2
2
Publication Release Date: October 2000
Preliminary W6694
D_LEN1
B_LEN1
1
D_LEN0
B_LEN0
0
Revision A1