![](http://datasheet.mmic.net.cn/330000/PM7367-PI_datasheet_16444408/PM7367-PI_84.png)
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
70
the free space is greater than the limit set by XFER[2:0]. The roamer also
decrements the end-of-packet count when the reader signals that it has passed
an end of a packet to the HDLC processor. If the HDLC is transmitting a packet
and the FIFO free space is greater than the free space trigger level and there are
no complete packets within the FIFO (end-of-packet count equal to zero), a per-
channel expedite flag is set. The roamer searches the expedite flags in a round-
robin fashion to decide which channel FIFO should make expedited data
requests to the TMAC block. If no expedite flags are set, the roamer searches
the request flags in a round-robin fashion to decide which channel FIFO should
make regular data requests to the TMAC block. The roamer informs the partial
packet writer of the channel FIFO to process, the FIFO free space and the type
of request it should make. The writer sends a request for data to the TMAC
block and writes the response data to the channel FIFO setting block full flags.
The writer reports back to the roamer the number of blocks and end-of-packets
transferred. The maximum amount of data transferred during one request is
limited by a software programmable limit.
The configuration of the HDLC processor is accessed using indirect channel
read and write operations as well as indirect block read and write operations.
When an indirect operation is performed, the information is accessed from RAM
during a null clock cycle identified by the TCAS block. Writing new provisioning
data to a channel resets the entire state vector.
8.8 Transmit Channel Assigner
The Transmit Channel Assigner block (TCAS) processes up to 32 channels.
Data for all channels is sourced from a single byte-serial stream from the
Transmit HDLC Controller / Partial Packet Buffer block (THDL). The TCAS
demultiplexes the data and assigns each byte to any one of 32 links. Each link is
independent and has its own associated clock. For each high-speed link
(TD[2:0]), the TCAS provides a six byte FIFO. For the remaining links
(TD[31:3]), the TCAS provides a holding register. The TCAS also performs
parallel to serial conversion to form a bit-serial stream. In the event where
multiple links are in need of data, TCAS requests data from upstream blocks on
a fixed priority basis with link TD[0] having the highest priority and link TD[31] the
lowest.
Links containing a T1 or an E1 stream may be channelised. Data at each time-
slot may be independently assigned to be sourced from a different channel. The
link clock is only active during time-slots 1 to 24 of a T1 stream and is inactive
during the frame bit. Similarly, the clock is only active during time-slots 1 to 31 of
an E1 stream and is inactive during the FAS and NFAS framing bytes. The most
significant bit of time-slot 1 of a channelised link is identified by noting the
absence of the clock and its re-activation. With knowledge of the transmit link