RELEASED
PM7380 FREEDM-32P672
DATA SHEET
PMC-1990262
ISSUE 5
FRAME ENGINE AND DATA LINK MANAGER 32P672
9
FUNCTIONAL DESCRIPTION
9.1 High Speed Multi-Vendor Integration Protocol (H-MVIP)
H-MVIP defines a synchronous, time division multiplexed (TDM) bus of Nx64
Kbps constant bit rate (CBR) data streams. Each 64 Kbps data stream (time-
slot) carries an 8-bit byte of HDLC traffic, as described in the following section,
and is characterised by 8 KHz framing. H-MVIP supports higher bandwidth
applications on existing telephony networks by fitting more time-slots into a 125
ꢁs frame. The FREEDM-32P672 supports H-MVIP data rates of 2.048 Mbps
and 8.192 Mbps with 32 or 128 time-slots per frame and associated clocking
frequencies of 4.096 and 16.384 MHz respectively. Figure 1 shows a diagram of
the H-MVIP protocol supported by the FREEDM-32P672 device.
Figure 1 – H-MVIP Protocol
125 us
Data Clock
(4, 16 MHz)
Frame Pulse Clock
(4 MHz)
Frame Pulse
(8 KHz)
Serial Data
B7
B8
B1
B2
TS 0
B8
B1
B2
TS 1
B7
B8
TS 31/127
TS 31/127
9.2 High-Level Data Link Control (HDLC) Protocol
Figure 2 shows a diagram of the synchronous HDLC protocol supported by the
FREEDM-32P672 device. The incoming stream is examined for flag bytes
(01111110 bit pattern) which delineate the opening and closing of the HDLC
packet. The packet is bit de-stuffed which discards a "0" bit which directly
follows five contiguous "1" bits. The resulting HDLC packet size must be a
multiple of an octet (8 bits) and within the expected minimum and maximum
packet length limits. The minimum packet length is that of a packet containing
two information bytes (address and control) and FCS bytes. For packets with
CRC-CCITT as FCS, the minimum packet length is four bytes while those with
CRC-32 as FCS, the minimum length is six bytes. An HDLC packet is aborted
when seven contiguous "1" bits (with no inserted "0" bits) are received. At least
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
38
PMC [ PMC-SIERRA, INC ]
