SAB82538 Datasheet, PDF (33/253 Pages) Infineon Technologies AG – ICs for Communications

SAB 82538
SAF 82538
2
Functional Description
2.1 General
The ESCC8 distinguishes itself from other communication controllers by its advanced
characteristics. The most important are:
q Eight independent serial channels.
q Support of HDLC, SDLC, BISYNC/MONOSYNC and Asynchronous protocols.
q Support of layer-2 functions (HDLC mode).
In addition to those bit-oriented functions commonly supported by HDLC controllers,
such as bit stuffing, CRC check, flag and address recognition, the ESCC8 provides a
high degree of procedural support.
In a special operating mode (auto-mode), the ESCC8 processes the information
transfer and the procedure handshaking (I- and S-frames of HDLC protocol)
autonomously. The only restriction is that the window size (= number of outstanding
unacknowledged frames) is limited to 1, which is sufficient for many applications. The
communication procedures are mainly processed between the communication
controllers and not between the attached processors. Thus the dynamic load on the
CPU and the software expense is greatly reduced.
The CPU is informed about the status of the procedure and has mainly to manage the
receive and transmit data. In order to maintain cost effectiveness and flexibility, the
handling of unnumbered (U) frames, and special functions such as error recovery in
case of protocol errors, are not implemented in hardware and must be done by the
user’s software.
q Extended support of different link configurations.
Besides the point-to-point configurations, the ESCC8 allows the implementation of
point-to-multipoint or multi-master configurations without additional hardware or
software expense.
In point-to-multipoint configurations, the ESCC8 can be used as a master or as a
slave station. Even when working as slave station, the ESCC8 can initiate the
transmission of data at any time. An internal function block provides means of idle and
collision detection and collision resolution, which are necessary if several stations
start transmitting simultaneously. Thus, a multi-master configuration is also possible.
q Telecom specific features.
In a special operating mode, the ESCC8 can transmit or receive data packets in one
of up to 64 time-slots of programmable width (clock mode 5). Furthermore, the ESCC8
can transmit or receive variable data portions within a defined window of one or more
clock cycles in conjunction with an external strobe signal (clock mode 1). These
features make the ESCC8 suitable for applications using time division multiplex
methods, such as time-slot oriented PCM systems or systems designed for packet
switching.
Semiconductor Group
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