SBI Bus Serializer ASSP Telecom Standard Product Data Sheet
Released
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2000168, Issue 5
324
13.11.2
Retrieving Messages
When reading messages from the receive FIFO in the WILC or PILC, the following procedure
should be followed:
Write a logic 1 to the RX_XFER_SYNC bit of the Receive Status and FIFO Synch Register
(09BH or 0ABH). This will initiate a read from the receive FIFO.
Read the RX_FI_BUSY bit in the Receive Status and FIFO Synch Register (09BH or 0ABH) or
wait a minimum of 4 SYSCLK cycles. If RX_FI_BUSY is a logic 0, continue to step 3. If it is
a logic 1, continue polling the RX_FI_BUSY bit.
Read the Receive Status and FIFO Synch Register (09BH or 0ABH) and check the state of the
CRC_ERR. If this bit is a logic 1, the current message in the FIFO had a CRC error and the
data is not reliable and the user may want to skip to the next message. This may be done by
writing logic 1 to the RX_XFER_SYNC bit (09BH or 0ABH), then returning to step 1.
Read the Receive FIFO Data High Register (096H or 0A6H).
Read the Receive FIFO Data Low Register (097H or 0A7H).
Read the RX_FI_BUSY bit in the Receive Status and FIFO Synch Register (09BH or 0ABH) or
wait a minimum of 4 SYSCLK cycles. If RX_FI_BUSY is a logic 0, continue to step 7. If it is
a logic 1, continue polling the RX_FI_BUSY bit.
Loop back to Step 4 until the entire message has been read out of the FIFO.
When reading more than one message from the receive FIFO, the RX_XFER_SYNC does not
have to be set between each message.
Before reading the any messages, the software may want to check how many messages are
contained in the receive FIFO. This can be done by reading the RX_MSG_LVL[3:0] bits in the
Receive Status and FIFO Synch Register (09BH or 0ABH). When reading these bits, the
RX_STTS_VALID bit must also be checked. If RX_STTS_VALID is a logic 1, the
RX_MSG_LVL[3:0] bits are valid. If RX_STTS_VALID is a logic 0, the RX_MSG_LVL[3:0]
bits are not valid and this register should be read again until RX_STTS_VALID is a logic 1.
13.11.3
Transmit Message Header Bytes
LINK[1:0]:
These bits reflect the state of the TX_LINK[1:0] bits in the Transmit Control
Register (093H or 0A3H).
PAGE[1:0]:
These bits reflect the state of the CMP value used by each of the MSU blocks.
PAGE[1] reflects the current memory page used by the IMSU. PAGE[0] reflects the current
memory page used by the OMSU.
USER[2:0]:
The USER[2] bit reflects the state of the IUSER2 input to the SBS. The
USER[1:0] bits transmitted by the WILC reflects the state of the TXWUSER[1:0] bits in
register 008H. The USER[1:0] bits transmitted by the PILC reflects the state of the
TXPUSER[1:0] bits in register 008H.