![](http://datasheet.mmic.net.cn/330000/PM8315_datasheet_16444435/PM8315_208.png)
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
193
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 TEMUX Master Interrupt Source
registers, and the TEMUX 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
TDPR Lower Interrupt Threshold should be set to such a value that sufficient
warning of an underrun is given. The FULLE, LFILLE, OVRE, and UDRE bits
are all set to logic 1 so an interrupt on INTB is generated upon detection of a
FIFO full state, a FIFO depth below the lower limit threshold, a FIFO overrun, or
a FIFO underrun. The following procedure should be followed to transmit HDLC
packets:
1. Wait for a complete packet to be transmitted. Once data is available to be
transmitted, then go to step 2.
2. Write the data byte to the TDPR Transmit Data register.
3. If all bytes of the packet have been written to the Transmit Data register, then
set the EOM bit in the TDPR Configuration register to logic 1. Go to step 1.
4. If there are more bytes in the packet to be sent, then go to step 2.
While performing steps 1 to 4, the processor should monitor for interrupts
generated by the TDPR. When an interrupt is detected, the TDPR Interrupt
Routine detailed in the following text should be followed immediately.
The TDPR will force transmission of the packet information when the FIFO depth
exceeds the threshold programmed with the UTHR[6:0] bits in the TDPR Upper
Transmit Threshold register. Unless an error condition occurs, transmission will