DS3134 datasheet(89/203 Pages) DALLAS

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DS3134

89 of 203

Bits 0 to 7 / HDLC Channel ID (HCID0 to HCID7).

00000000 (00h) = HDLC Channel Number 1

11111111 (FFh) = HDLC Channel Number 256

Bit 14 / Indirect Access Read/Write (IARW). When the host wishes to write data to set the internal

Receive Starting Block Pointer, this bit should be written to a zero by the host. This causes the device to

take the data that is currently present in the RFSBP register and write it to the channel location indicated

by the HCID bits. When the device has completed the write, the IAB will be set to zero.

Note: The RFSBP is a write only register. Once this register has been written to and operation started,

DS3134 internal state machine will change the value in this register.

Bit 15 / Indirect Access Busy (IAB). When an indirect read or write access is in progress, this read only

bit will be set to a one. During a read operation, this bit will be set to a one until the data is ready to be

read. It will be set to zero when the data is ready to be read. During a write operation, this bit will be set

to a one while the write is taking place. It will be set to zero once the write operation has completed.

RFSBP

0904h

5432

RSBP7

RSBP6

RSBP5

RSBP4

RSBP3

RSBP2

RSBP1

RSBP0

n/a

RSBP9

RSBP8

Note: Bits that are underlined are read only, all other bits are read-write.

Bits 0 to 9 / Starting Block Pointer (RSBP0 to RSBP9).

These 10 bits determine which of the

1024 blocks within the receive FIFO, the host wants the device to configure as the starting block for a

particular HDLC channel. Any of the blocks within a chain of blocks for a HDLC channel can be

configured as the starting block. When these 10 bits are read, they will report the current Block Pointer

being used to write data into the Receive FIFO from the HDLC Layer 2 engines.

0000000000 (000h) = Use Block 0 as the Starting Block

0111111111 (1FFh) = Use Block 511 as the Starting Block

1111111111 (3FFh) = Use Block 1023 as the Starting Block

DS3134 Datasheet(PDF) 89 Page - Dallas Semiconductor