The Philips Semiconductors SCC68692 Dual Universal Asynchronous Receiver/Transmitter (DUART) is compatible with SCN68681. It is a single-chip CMOS-LSI communications device that provides two full-duplex asynchronous receiver/transmitter channels in a single package. It is compatible with other S68000 family devices and can also interface easily with other microprocessors. The DUART can be used in a polled or interrupt driven systems. The operating mode and data format of each channel can be programmed independently. Additionally, each receiver and transmitter can select its operating speed as one of eighteen fixed baud rates, a 16X clock derived from a programmable counter/timer, or an external 1X or 16X clock. The baud rate generator and counter/timer can operate directly from a crystal or from external clock inputs. The ability to independently program the operating speed of the receiver and transmitter make the DUART particularly attractive for dual-speed channel applications such as clustered terminal systems. Each receiver is quadruple buffered to minimize the potential of receiver over-run or to reduce interrupt overhead in interrupt driven systems.
The SCC68692 DUART provides two independent full‑duplex asynchronous receiver/transmitter channels in a single CMOS‑LSI package. Each channel can be programmed for its own data format, baud rate and clock source, supporting 22 fixed rates from 50 to 115.2 kbaud as well as user‑defined rates.
The device includes a 6‑bit input port and an 8‑bit output port that can be used as general‑purpose I/O or for clock/interrupt functions. It offers a versatile interrupt system with eight maskable sources, power‑down mode, and operates over a commercial‑industrial temperature range. Packages are available in 40‑pin DIP, 44‑pin PLCC and ceramic dual‑in‑line (Cerdip).
| Operating temperature range | -40 °C to +85 °C |
|---|---|
| Maximum data transfer rate | 1X – 1 MB/s, 16X – 125 kB/s |
| Baud‑rate options | 22 fixed rates 50 to 115.2 kbaud, plus user‑defined rates |
The DUART provides a single active‑low interrupt output that can be triggered by any of eight maskable internal conditions.
Commercial versions operate from 0 °C to +70 °C, while industrial versions cover –40 °C to +85 °C.