Introduction
The Enhanced Serial Communication Controller ESCC2 (SAB 82532/SAF 82532) is a multiprotocol data communication controller with two symmetrical serial channels. It has been designed to implement high-speed communication links and to reduce hardware and software overhead needed for serial synchronous/asynchronous communications.
Each channel contains an independent clock generator, DPLL, encoder/decoder and programmable protocol hardware. Data communication with asynchronous, synchronous character oriented, and HDLC based protocols with extended support of X.25 LAPB, the ISDN LAPD, and SDLC protocols is implemented. Like the SAB 82525 (HSCX) which is a functional subset of the ESCC2, the ESCC2 is capable of handling a large set of layer-2 protocol functions independently of the host processor.

FEATUREs
Serial Interface
• Two independent full duplex serial channels
   – On chip clock generation or external clock source
   – On chip DPLL for clock recovery of each channel
   – Two independent baud rate generators
   – Independent time-slot assignment for each channel with programmable time-slot length (1 … 256 bits)
• Async, sync character oriented (MONOSYNC/BISYNC) or HDLC/SDLC modes (including SDLC LOOP)
• Transparent receive/transmit of data bytes without framing
• NRZ, NRZI, FM and Manchester encoding
• Modem control lines (RTS, CTS, CD)
• CRC support:
   – HDLC/SDLC: CRC-CCITT or CRC-32 (automatic handling for transmit/receive direction)
   – BISYNC: CRC-16 or CRC-CCITT (support for transmit direction)
• Support of bus configuration by collision detection and resolution
• Statistical multiplexing
• Continuous transmission of 1 to 32 bytes possible
• Programmable preamble (8 bit) with selectable repetition rate (HDLC/SDLC and BISYNC)
• Data rate up to 10 Mbit/s
• Master clock mode with data rate up to 4 Mbit/s

Protocol Support (HDLC/SDLC)
• Various types of protocol support depending on operating mode
   – Auto mode (automatic handling of S- and I-frames)
   – Non-auto mode
   – Transparent mode
• Handling of bit oriented functions
• Support of LAPB/LAPD/SDLC/HDLC protocol in auto mode (I- and S-frame handling)
• Modulo-8 or modulo-128 operation
• Programmable time-out and retry conditions
• Programmable maximum packet size checking

MP Interface and Ports
• 64 byte FIFOs per channel and direction (byte or word access)
• 8/16 bit microprocessor bus interface (Intel or Motorola type)
• All registers directly accessible (byte and word access)
• Efficient transfer of data blocks from/to system memory via DMA or interrupt request
• Support of Daisy Chaining and Slave Operation with Interrupt Vector generation
• 8-bit programmable bi-directional universal port

General
• Advanced CMOS technology
• Low power consumption: active 40 mW at 2 MHz/standby 5 mW (typical values)
• P-LCC-68 Package
• P-MQFP-80 Package

APPLICATIONs
• Universal, multiprotocol communication board for Workstation- and PC-boards
• Terminal controllers
• Computer peripherals
• Time slotted packet networks
• Multimaster communication networks
• LANs