STANDARD PRODUCT
PM4328 TECT3
DATASHEET
PMC-2011596
ISSUE 1
HIGH DENSITY T1/E1 FRAMER
AND M13 MULTIPLEXER
Clear, and TDPR Transmit Data register should be accessed (with respect to
WRB rising edge and RDB falling edge) at a rate no faster than 1/8 that of the
selected TDPR high-speed system clock. This time is used by the high-speed
system clock to sample the event, write the FIFO, and update the FIFO status.
Instantaneous variations in the high-speed reference clock frequencies (e.g. jitter
in the line clock) must be considered when determining the procedure used to
read and write the TDPR registers.
Upon reset of the TECT3, the TDPR should be disabled by setting the EN bit in
the TDPR Configuration Register to logic 0 (default value). An HDLC all-ones
Idle signal will be sent while in this state. The TDPR is enabled by setting the EN
bit to logic 1. The FIFOCLR bit should be set and then cleared to initialize the
TDPR FIFO. The TDPR is now ready to transmit.
To initialize the TDPR, the TDPR Configuration Register must be properly set. If
FCS generation is desired, the CRC bit should be set to logic 1. If the block is to
be used in interrupt driven mode, then interrupts should be enabled by setting
the FULLE, OVRE, UDRE, and LFILLE bits in the TDPR Interrupt Enable register
to logic 1. The TDPR operating parameters in the TDPR Upper Transmit
Threshold and TDPR Lower Interrupt Threshold registers should be set to the
desired values. The TDPR Upper Transmit Threshold sets the value at which the
TDPR automatically begins the transmission of HDLC packets, even if no
complete packets are in the FIFO. Transmission will continue until the current
packet is transmitted and the number of bytes in the TDPR FIFO falls to, or
below, this threshold level. The TDPR will always transmit all complete HDLC
packets (packets with EOM attached) in its FIFO. Finally, the TDPR can be
enabled by setting the EN bit to logic 1. If no message is sent after the EN bit is
set to logic 1, continuous flags will be sent.
The TDPR can be used in a polled or interrupt driven mode for the transfer of
data. In the polled mode the processor controlling the TDPR must periodically
read the TDPR Interrupt Status register to determine when to write to the TDPR
Transmit Data register. In the interrupt driven mode, the processor controlling
the TDPR uses the INTB output, the one of the TECT3 Master Interrupt Source
registers, and the TECT3 TDPR Interrupt Status registers to identify TDPR
interrupts which determine when writes can or must be done to the TDPR
Transmit Data register.
Interrupt Driven Mode:
The TDPR automatically transmits a packet once it is completely written into the
TDPR FIFO. The TDPR also begins transmission of bytes once the FIFO level
exceeds the programmable Upper Transmit Threshold. The CRC bit can be set
to logic 1 so that the FCS is generated and inserted at the end of a packet. The
PROPRIETARY AND CONFIDENTIAL
141
PMC [ PMC-SIERRA, INC ]
