Rainbow Electronics DS3134 User Manual

Page 89

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

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