AT&T Co has expanded its Unite family of Integrated Services Digital Networking chips with two new parts, the T7112 Asynchronous Receiver/Transmitter Interface, Arti, and the LC1046 Pulse Code Modulation Transceiver. The Arti is an asynchronous communications interface that automatically performs speedmatching on-chip. Speedmatching is a process that detects the speed of incoming data and sends that information to the microprocessor. The Arti adjusts to the appropriate speed and notifies the microprocessor that the change has been made. In other systems, claims AT&T, the speed must be synchronised by the system user or programmer through a software change or by setting a dual in-line package, DIP, switch. Speedmatching is also claimed to improve accuracy while eliminating 95% of the software otherwise necessary to synchronise the data speed, thereby freeing up the microprocessor to perform other functions. 8051, 8088 As an asynchronous interface to terminals or modems, the Arti provides standard universal asynchronous receiver/transmitter, Uart, functions with additional data buffering. This circuit can be used as a single channel, half- or full-duplex interface for simultaneous transmitting and/or receiving with data communications equipment and data terminal equipment. Applications include workstations, integrated modems and ISDN terminal adaptors. This is claimed to allow greater flexibility in the reading and writing of buffers, which lessens the incidence of receiver overrun or transmitter underrun while reducing the associated interrupt overhead. Running at 8MHz, the T7112 Arti can transmit and receive data at rates of 250 to 250,000 bps. The Arti is compatible with the bus protocol and timing specifications of the 16MHz Intel 8051 microcontroller and 8MHz 8088 microprocessor and may be used in either a polled or interrupt driven system. Full features of the T7112 Asynchronous Receiver/Transmitter Interface are: programmable data format, seven data bits plus parity, odd, even, no parity, parity, framing, and overrun error detection and interrupt; 10 bit start/stop serial data, DTR/DSR, Data Terminal Ready/Data Set Ready; general purpose input/output pins; transmit/receive first in/first out; fifo, status bits indicating fifo levels; programmable on-chip baud rate generator (250- 250,000 bps); TTL transistor-transistor logic, compatible with three statable outputs; flexible polling capabilities; programmable transmit interrupt systems; fill level interrupt of receive FIFOs; recieve break detection and error interrupt; empty level of transmit FIFO and error interrupt; line break detection and generation/Interruption receive break detect; Intel 8088 (8MHz) Microprocessor and 80C51 (16MHz) Microcontroller interface with no wait states; Clear-to-send/request-to-send, CTS/RTS; selectable signals for DTE or DCE modes and flow control; single +5 V power supply; low power, 1.25 micron CMOS technology; maximum power dissipation of 150 milliwatts. Full duplex The device is now available in a 24-pin plastic DIP and later will be available in the 28-pin surface mount package SOJ (T7112- EC). The Arti is priced at $10 in quantities of 1,000. The part is available now in production quantities. The LC1046 PCM Transceiver is a fully integrated digital signalling interface and requires only two line interface transformers, three input terminations resistors, and one capacitor to provide full duplex transmit and receive, interfacing both the DS-1 and DS-1C rates between a DSX and terminal equipment. These signals, which cross-connect at standard interface points within central offices, form the backbone of inter-office digital data transmission for telephone switching cross-connections. Potential users of the LC1046 PCM include all big terminal equipment manufacturers, as well as PABX, T1 multiplexer, local area network and T1 modem manufacturers. The LC1046 PCM ISDN Transceiver is the first single chip interface being used in terminal equipment. As the only self contained interface available, it saves costs associated with existi
ng ISDN solutions requiring several devices. The LC1046 also performs on-chip interface functions for a US T1 or T1C system. These include receive pulse conditioning, timing recovery, and transmit pulse equalisation functions. The LC1046 PCM can be used to interface networking equipment such as subscriber line carriers, channel banks, digital access and cross connect switches, multiplexers, switching systems and customer premises equipment such as PABXs, T1 multiplexers, local area networks, and channel service units or T1 modems. Monolithic clock Full features of the LC1046 PCM Transceiver are as follows: fully integrated DS-1/DS-1C line transmit and receive interface, compatible with technical advisory number 34, TA34, and PUB 43802 specifications; on-chip transmit equalisation; monolithic clock recovery; pin-selectable B8ZS coder and encoder; loopback modes for fault isolation; multiple link-status and alarm indicators; minimal external circuitry required – it can be used with ABAM cable, as well as other cable types and T1 or T1C line interface and single-chip ISDN Primary Rate Interface, PRI; develops the required pulse shape at the DS-1 or DS-1C and cross-connects for cable distances of up to 655 feet over twisted pair copper cable; requires only a +5V supply and operates from minus 40`C to plus 85`C; operating power dissipation – a key consideration in these per-line devices; is less than 500mW during normal transmission, and 350mW during standby all zero data transmission; on-chip receive pulse conditioning timing recovery, and transmit pulse equalisation function; built-in status monitoring function. The LC1046 PCM Transceiver is available now in production quantities and is priced at $26 in quantities of 1000. For device assessment, an LC1046 evalu-ation board will be available later this year. Both devices will be manufactured at AT&T’s Allentown, Pennsylvania production facility.
