DS26401 datasheet(83/309 Pages) DALLAS

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DS26401 Octal T1/E1/J1 Framer

8.16 T1 Bit-Oriented Code (BOC) Controller

The DS26401 contains a BOC generator on the transmit side and a BOC detector on the receive side. The BOC

function is available only in T1 mode.

In ESF mode, the DS26401 continuously monitors the receive message bits for a valid BOC message. The BOC-

detect (BD) status bit at RLS7.0 is set once a valid message has been detected for time determined by the receive-

BOC-filter bits RBF0 and RBF1 in the RBOCC register. The 6-bit BOC message is available in the RBOC register.

Once the user has cleared the BD bit, it remains clear until a new BOC is detected (or the same BOC is detected

following a BOC-clear event). The BOC-clear (BC) bit at RLS7.1 is set when a valid BOC is no longer being

detected for a time determined by the receive-BOC-disintegration bits RBD0 and RBD1 in the RBOCC register.

The BD and BC status bits can create a hardware interrupt on the INT signal as enabled by the associated interrupt

mask bits in the RIM7 register.

RBOCC

Receive BOC Control Register

015h + (200h x n) : where n = 0 to 7, for Ports 1 to 8

Bit #

Name

RBR

—

RBD1

RBD0

—

RBF1

RBF0

—

Default

Bits 0, 3, 6 / Unused. Must be set = 0 for proper operation.

Bits 1 to 2 / Receive-BOC-Filter Bits (RBF0, RBF1).

The BOC filter sets the number of consecutive patterns that

must be received without error prior to an indication of a valid message.

RBF1

RBF0

Consecutive BOC Codes for Valid Sequence Identification

None

7 (Note 1)

Bits 4 to 5 / Receive-BOC-Disintegration Bits (RBD0, RBD1).

The BOC Disintegration filter sets the number of

message bits that must be received without a valid BOC in order to set the BC bit indicating that a valid BOC is no

longer being received.

RBD1

RBD0

Consecutive Message Bits for BOC Clear Identification

64 (Note 1)

Bit 7 / Receive-BOC Reset (RBR).

A 0-to-1 transition resets the BOC circuitry. Must be cleared and set again for a

subsequent reset. Modifications to the RBF0, RBF1, RBD0, and RBD1 bits are not applied to the BOC controller

until a BOC reset has been completed.

Note 1: The DS26401’s BOC controller does not integrate and disintegrate concurrently. Therefore, if the maximum integration time and the

maximum disintegration time are used together, BOC messages that repeat fewer than 11 times may not be detected.

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