
PEB 20560
Operational Description
Semiconductor Group
3-3
2003-08
3.1.3
EPIC
-1 Operation
The EPIC-1 component of the ELIC is principally an intelligent switch of PCM-data
between two serial interfaces, the system interface (PCM-interface) and the configurable
interface (CFI). Up to 128 channels per direction can be switched dynamically between
the CFI and the PCM-interfaces. The EPIC-1 performs non-blocking space and time
switching for these channels which may have a bandwidth of 16, 32 or 64 kbit/s.
Both interfaces can be programmed to operate at different data rates of up to
8.192 Mbit/s. The PCM-interface consists of up to four duplex ports with a tri-state
control signal for each output line. The configurable interface can be selected to provide
either four duplex ports or 8 bi-directional (I/O) ports.
The configurable interface incorporates a control block (layer-1 buffer) which allows the
μ
P to gain access to the control channels of an IOM- (ISDN-Oriented Modular) or SLD-
(Subscriber Line Data) interface. The EPIC-1 can handle the layer-1 functions buffering
the C/I and monitor channels for IOM compatible devices and the feature control and
signaling channels for SLD compatible devices. One major application of the EPIC-1 is
therefore as line card controller on digital and analog line cards. The layer-1 and codec
devices are connected to the CFI, which is then configured to operate as, IOM-2, SLD
or multiplexed IOM-1 interface.
The configurable interface of the EPIC-1 can also be configured as plain PCM-interface
i.e. without IOM- or SLD-frame structure. Since it’s possible to operate the two serial
interfaces at different data rates, the EPIC-1 can then be used to adapt two different
PCM- systems.
The EPIC-1 can handle up to 32 ISDN-subscribers with their 2B
+
D channel structure
or up to 64 analog subscribers with their 1B channel structure in IOM-configuration. In
SLD- configuration up to 16 analog subscribers can be accommodated.
The system interface is used for the connection to a PCM-back plane. On a typical digital
line card, the EPIC-1 switches the ISDN B-channels and, if required, also the D-channels
to the PCM-back plane. Due to its capability to dynamically switch the 16-kbit/s
D-channel, the EPIC-1 is one of the fundamental building blocks for networks with either
central, decentral or mixed signaling and packet data handling architecture.
3.1.3.1
PCM-Interface
The serial PCM-interface provides up to four duplex ports consisting each of a data
transmit (TxD#), a data receive (RxD#) and a tri-state control (TSC#) line. The transmit
direction is also referred to as the upstream direction, whereas the receive direction is
referred to as the downstream direction.
Data is transmitted and received at normal TTL / CMOS-levels, the output drivers being
of the tri-state type. Unassigned time-slots may be either be tri-stated, or programmed
to transmit a defined idle value. The selection of the states “high impedance” and “idle
value” can be performed with a two bit resolution. This tri-state capability allows several