ISAC-SX

The ISDN Subscriber Access Controller ISAC-SX integrates a D-channel HDLC controller and a four wire S/T interface used to link voice/data terminals to the ISDN. It is based on the ISAC-S PEB 2086, and provides enhanced features and functionality. It includes the S-transceiver (Layer 1), an HDLC controller for the D-channel and one B-channel protocol controller (HDLC or transparent) with reduced features dedicated for firmware download via the B-channel.

The system integration is simplified by several configurations of the parallel microcontroller interface selected via pin strapping. They include multiplexed and demultiplexed interface selection as well as the optional indirect register access mechanism which reduces the number of necessary registers in the address space to 2 locations. The ISAC-SX also provides a serial control interface (SCI).

The FIFO size of the cyclic D-channel buffer is 64 bytes per direction with programmable block size (threshold). Besides TE mode the S-transceiver supports other terminal relevant operation modes like line termination subscriber side (LT-S), line termination trunk side (LT-T) and NT applications (NT, Intelligent NT mode).

An auxiliary I/O port has been added with interrupt capabilities on two input lines. These programmable I/O lines may be used to connect peripheral components to the ISAC-SX which need software control or have to forward status information to the host.

Three programmable LED outputs can be used to indicate certain status information, one of them is capable to indicate the activation status of the S-interface automatically. The ISAC-SX is produced in advanced CMOS technology.