
STANDARD PRODUCT
PM8315 TEMUX
DATASHEET
PMC-1981125
ISSUE 7
HIGH DENSITY T1/E1 FRAMER  WITH
INTEGRATED VT/TU MAPPER AND M13 MUX
PROPRIETARY AND CONFIDENTIAL
194
not stop until the last byte of all complete packets is transmitted and the FIFO
depth is at or below the threshold limit.  The user should watch the FULLI and
LFILLI interrupts to prevent overruns and underruns.
TDPR Interrupt Routine:
Upon assertion of INTB, the source of the interrupt must first be identified by
reading the TEMUX Master Interrupt Source register (0020H) followed by
reading one of the second level master interrupt source registers T1E1INT1,
T1E1INT2, T1E1INT3, T1E1INT4 or DS3INT.  Once the source of the interrupt
has been identified as the TDPR in use, then the following procedure should be
carried out:
1. Read the TDPR Interrupt Status register.
2. If UDRI=1, then the FIFO has underrun and the last packet transmitted has
been corrupted and needs to be retransmitted.  When the UDRI bit transitions
to logic 1, one Abort sequence and continuous flags will be transmitted.  The
TDPR FIFO is held in reset state.  To re-enable the TDPR FIFO and to clear
the underrun, the TDPR Interrupt Status/UDR Clear register should be written
with any value.
3. If OVRI=1, then the FIFO has overflowed.  The packet of which the last byte
written into the FIFO belongs to, has been corrupted and must be
retransmitted.  Other packets in the FIFO are not affected.  Either a timer can
be used to determine when sufficient bytes are available in the FIFO or the
user can wait until the LFILLI interrupt is set, indicating that the FIFO depth is
at the lower threshold limit.
If the FIFO overflows on the packet currently being transmitted (packet is
greater than 128 bytes long), OVRI is set, an Abort signal is scheduled to be
transmitted, the FIFO is emptied, and then flags are continuously sent until
there is data to be transmitted.  The FIFO is held in reset until a write to the
TDPR Transmit Data register occurs.  This write contains the first byte of the
next packet to be transmitted.
4. If FULLI=1 and FULL=1, then the TDPR FIFO is full and no further bytes can
be written.  When in this state, either a timer can be used to determine when
sufficient bytes are available in the FIFO or the user can wait until the LFILLI
interrupt is set, indicating that the FIFO depth is at the lower threshold limit.
If FULLI=1 and FULL=0, then the TDPR FIFO had reached the FULL state
earlier, but has since emptied out some of its data bytes and now has space
available in its FIFO for more data.