Rainbow Electronics DS31256 - Manual (Page 77)

DS31256
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Bit 14/Indirect Access Read/Write (IARW). When the host wishes to write data to set the internal receive
starting block pointer, the host should write this bit to 0. This causes the device to take data that is currently
presetn in the RFSBP register and write it to the channel location indicated by the HCID bits. When the device
completes the write, the IAB is set to 0.
Note: The RFSBPIS is write-only memory. Once this register has been written to and the operation has started,
the DS31256 internal state machine changes the value in this memory.
Bit 15/Indirect Access Busy (IAB). When an indirect read or write access is in progress, this read-only bit is set
to 1. During a read operation, this bit is set to 1 until the data is ready to be read. It is set to 0 when the data is
ready to be read. During a write operation, this bit is set to 1 while the write is taking place. It is set to 0 once the
write operation completes.
Register Name:
RFSBP
Register Description: Receive FIFO Starting Block Pointer
Register Address:
0904h
Bit # 7 6 5 4 3 2 1 0
Name RSBP7 RSBP6 RSBP5 RSBP4 RSBP3 RSBP2 RSBP1 RSBP0
Default
Bit # 15 14 13 12 11 10 9 8
Name n/a n/a n/a n/a n/a n/a RSBP9 RSBP8
Default
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 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 an HDLC channel can be configured as the starting block. When these bits
are read, they 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
Register Name:
RFBPIS
Register Description: Receive FIFO Block Pointer Indirect Select
Register Address:
0910h
Bit # 7 6 5 4 3 2 1 0
Name BLKID7 BLKID6 BLKID5 BLKID4 BLKID3 BLKID2 BLKID1 BLKID0
Default 0 0 0 0 0 0 0 0
Bit # 15 14 13 12 11 10 9 8
Name IAB IARW n/a n/a n/a n/a BLKID9 BLKID8
Default 0 0 0 0 0 0 0 0
Note: Bits that are underlined are read-only; all other bits are read-write.
Bits 0 to 9/Block ID (BLKID0 to BLKID9)
0000000000 (000h) = block number 0
0111111111 (1FFh) = block number 511
1111111111 (3FFh) = block number 1023