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PM7346 S/UNI-QJET
DATASHEET
PMC-960835
ISSUE 6
SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE
328
event and update the FIFO status. Instantaneous variations in the high-speed
reference clock frequencies (e.g. jitter in the receive line clock) must be
considered when determining the procedure used to read RDLC registers.
On power up of the system, the RDLC should be disabled by setting the EN bit in
the Configuration Register to logic 0 (default state). The RDLC Interrupt Control
register should then be initialized to enable the INT output and to select the FIFO
buffer fill level at which an interrupt will be generated. If the INTE bit is not set to
logic 1, the RDLC Status register must be continuously polled to check the
interrupt status (INTR) bit.
After the RDLC Interrupt Control register has been written, the RDLC can be
enabled at any time by setting the EN bit in the RDLC Configuration register to
logic 1. When the RDLC is enabled, it will assume the link status is idle (all ones)
and immediately begin searching for flags. When the first flag is found, an
interrupt will be generated, and a dummy byte will be written into the FIFO buffer.
This is done to provide alignment of link up status with the data read from the
FIFO. When an abort character is received, another dummy byte and link down
status is written into the FIFO. This is done to provide alignment of link down
status with the data read from the FIFO. It is up to the controlling processor to
check the COLS bit in the RDLC Status register for a change in the link status. If
the COLS bit is set to logic 1, the FIFO must be emptied to determine the current
link status. The first flag and abort status encoded in the PBS bits is used to set
and clear a Link Active software flag.
When the last byte of a properly terminated packet is received, an interrupt is
generated. While the RDLC Status register is being read the PKIN bit will be
logic 1. This can be a signal to the external processor to empty the bytes
remaining in the FIFO or to just increment a number-of-packets-received count
and wait for the FIFO to fill to a programmable level. Once the RDLC Status
register is read, the PKIN bit is cleared to logic 0 . If the RDLC Status register is
read immediately after the last packet byte is read from the FIFO, the PBS[2] bit
will be logic 1 and the CRC and non-integer byte status can be checked by
reading the PBS[1:0] bits.
When the FIFO fill level is exceeded, an interrupt is generated. The FIFO must
be emptied to remove this source of interrupt.
The RDLC can be used in a polled or interrupt driven mode for the transfer of
frame data. In the polled mode, the processor controlling the RDLC must
periodically read the RDLC Status register to determine when to read the RDLC
Data register. In the interrupt driven mode, the processor controlling the RDLC
uses the S/UNI-QJET INTB output, the S/UNI-QJET Clock Activity Monitor and