z02201 ZiLOG Semiconductor, z02201 Datasheet - Page 67

• Manufacturer Part Number: z02201
• Description: Z02201 V.22bis Data Pump With Integrated Afe
• Manufacturer: ZiLOG Semiconductor

Using HDLC
PS000904-0107
HDLC Operation
Notes:
4. Set CONFIG to 8 (V.22BIS ANSWER). After setting Config, the host should be
5. When the data pump establishes a V.22bis connection, and is ready to
The data pump includes HDLC firmware operating in all data modes. The HDLC
firmware performs all the necessary operations to frame host-supplied data into
HDLC format, including automatic opening and closing flag generation, zero inser-
tion and deletion, flag and abort detection, and CRC checksum computation and
checking.
During HDLC operation, the data pump frames host-supplied asynchronous data
into a synchronous data stream in the transmitter, and extracts the same asyn-
chronous data from the received synchronous data stream in the receiver. The
inclusion of 16-bit cyclic redundancy check (CRC) information in the frames allows
the receiving host to check whether the data has been correctly received.
HDLC data is sent in frames. A frame consists of a number of bytes, each com-
posed of 8 data bits. A frame contains an opening flag, frame data bytes, two CRC
checksum bytes, and a closing flag, respectively. Opening flags and closing flags
indicate the start and the end of a frame, respectively.
prepared to receive data from the remote modem. The data pump holds the
received data to marks (receives nothing) until the modem is able to receive
data from the remote modem.
transmit data to the remote modem, it sets Reg5, bit
now be transmitted or received between the modems.
The data pump sets Reg5, bit 1 (CDET) to 0 during carrier
dropouts, retrains, and when the remote modem hangs up the
telephone line. Depending on the data mode, the host may
use Reg5, bit 1 (CDET), Reg5, bit 2 (RTRND), Dpctrl.EQE,
EQMlev and EQMMaxThresh to determine when the remote
modem has initiated a retrain, or has hung up the telephone
line.
During 2400 bps V.22bis data mode, the host may use
Dpctrl.EQE and EQMMaxThresh or EQMlev, to determine
when to initiate a retrain (see
improve the quality of the connection.
V.22BIS Data Pump with Integrated AFE
Table
20, Mstatus.RETRAIN) to
1
(CDET) to
1
. Data may
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