Overview
The PEB 20550 (Extended Line Card Controller) is a highly integrated controller circuit optimized for line card and key system applications. It combines all functional blocks necessary to manage up to 32 digital (ISDN or proprietary) or 64 analog subscribers.
The switching and layer-1 control capability of the EPIC-1 (PEB 2055) constitutes a major functional block of the ELIC.

Features
Switching (EPIC®-1)
• Non-blocking switch for 32 digital (e.g. ISDN) or 64 voice subscribers
    – Bandwidth 16, 32, or 64 kbit/s
    – Two consecutive 64-bit/s channels can be switched as a single 128-kbit/s channel
• Freely programmable time slot assignment for all subscribers
• Synchronous µP-access to two selected channels
• Two types of serial interfaces independently programmable over a wide data range (128 - 8192 kbit/s)
    – PCM-interface
        Tristate control signals for external drivers
        Programmable clock shift
        Single or double data clock
    – Configurable interface
        Configurable for IOM-, SLD- and PCM-applications
        High degree of flexibility for datastream adaption
        Programmable clockshift
        Single or double data clock

Handling of Layer-1 Functions (EPIC®-1)
• Change detection for C/I-channel (IOM-configuration) or feature control (SLD-configuration)
• Additional last-look logic for feature control (SLD-configuration)
• Buffered monitor (IOM-configuration) or signaling channel (SLD-configuration)

Handling of Layer-2 Functions (SACCO)
• Two independent full duplex HDLC-channels
    – Serial interface
        Data rate up to 4 Mbit/s
        Independent time slot assignment for each channel with programmable time slot
        length (1-256 bits)
        Support of bus configuration with collision resolution
        Continuous transmission of 1 to 32 bytes possible
    – Protocol support
        Auto-mode, fully compatible to PEB 2050 (PBC) protocol
        Non-auto mode, address recognition capability
        Transparent mode, HDLC-framing only
        Extended transparent mode, fully transparent without HDLC-framing
    – 64-bytes FIFO’s per HDLC-channel and direction

D-channel Multiplexing (D-channel arbiter)
• Serving of multiple subscribers with one HDLC-controller
• Full duplex signaling protocols (e.g. LAPD or proprietary) supported
• Programmable priority scheme
• Broadcast transmission

Line Card Glue Logic
• Power-up reset generator
• Watchdog timer
• Parallel ports (8-bit input, 4-bit I/O)

Boundary Scan Support
• Fully IEEE 1149.1 compatible
• 32-bit device identification register

Bus Interface
• Siemens/Intel or Motorola type µP-interface
• 8-bit demultiplexed bus interface
• FIFO-access interrupt or DMA controlled