DS2155 datasheet(134/262 Pages) DALLAS

134 / 262 page

DS2156

134 of 262

H1TC, H2TC

HDLC #1 Transmit Control

HDLC #2 Transmit Control

90h, A0h

Bit #

Name

NOFS

TEOML

THR

THMS

TFS

TEOM

TZSD

TCRCD

Default

Bit 0/Transmit CRC Defeat (TCRCD). A 2-byte CRC code is automatically appended to the outbound message.

This bit can be used to disable the CRC function.

0 = enable CRC generation (normal operation)

1 = disable CRC generation

Bit 1/Transmit Zero-Stuffer Defeat (TZSD). The zero-stuffer function automatically inserts a 0 in the message

field (between the flags) after five consecutive 1s to prevent the emulation of a flag or abort sequence by the data

pattern. The receiver automatically removes (destuffs) any 0 after five 1s in the message field.

0 = enable the zero stuffer (normal operation)

1 = disable the zero stuffer

Bit 2/Transmit End of Message (TEOM). Should be set to a 1 just before the last data byte of an HDLC packet is

written into the transmit FIFO at HxTF. If not disabled through TCRCD, the transmitter automatically appends a 2-

byte CRC code to the end of the message.

Bit 3/Transmit Flag/Idle Select (TFS). This bit selects the intermessage fill character after the closing and before

the opening flags (7Eh).

0 = 7Eh

1 = FFh

Bit 4/Transmit HDLC Mapping Select (THMS)

0 = transmit HDLC assigned to channels

1 = transmit HDLC assigned to FDL (T1 mode), Sa bits (E1 mode)

Bit 5/Transmit HDLC Reset (THR). Resets the transmit HDLC controller and flushes the transmit FIFO. An

abort followed by 7Eh or FFh flags/idle is transmitted until a new packet is initiated by writing new data into the

FIFO. Must be cleared and set again for a subsequent reset.

0 = normal operation

1 = reset transmit HDLC controller and flush the transmit FIFO

Bit 6/Transmit End of Message and Loop (TEOML). To loop on a message, this bit should be set to a 1 just

before the last data byte of an HDLC packet is written into the transmit FIFO. The message repeats until the user

clears this bit or a new message is written to the transmit FIFO. If the host clears the bit, the looping message

completes, then flags are transmitted until a new message is written to the FIFO. If the host terminates the loop by

writing a new message to the FIFO, the loop terminates, one or two flags are transmitted, and the new message

starts. If not disabled through TCRCD, the transmitter automatically appends a 2-byte CRC code to the end of all

messages. This is useful for transmitting consecutive SS7 FISUs without host intervention.

Bit 7/Number of Flags Select (NOFS)

0 = send one flag between consecutive messages

1 = send two flags between consecutive messages

DS2155 Datasheet(PDF) 134 Page - Dallas Semiconductor

DS2155 Datasheet(HTML) 134 Page - Dallas Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL