DESCRIPTION

The Philips Semiconductors SCN68681 Dual Universal Asynchronous Receiver/Transmitter (DUART) is a single-chip MOS-LSI communications device that provides two independent 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 polled or interrupt driven systems.

FEATURES

• S68000 bus compatible

• Dual full-duplex asynchronous receiver/transmitter

• Quadruple buffered receiver data registers

• Programmable data format

– 5 to 8 data bits plus parity

– Odd, even, no parity or force parity

– 1, 1.5 or 2 stop bits programmable in 1/16-bit increments

• Programmable baud rate for each receiver and transmitter selectable from:

– 22 fixed rates: 50 to 115.2k baud

– Non-standard rates to 115.2kb

– Non-standard user-defined rate derived from programmable counter/timer

– External 1X or 16X clock

• 16-bit programmable Counter/Timer

• Parity, framing, and overrun error detection

• False start bit detection

• Line break detection and generation

• Programmable channel mode

– Normal (full-duplex)

– Automatic echo

– Local loopback

– Remote loopback

• Multi-function programmable 16-bit counter/timer

• Multi-function 6-bit input port

– Can serve as clock or control inputs

– Change-of-state detection on four inputs

– 100kΩ typical pull-up resistors

• Multi-function 8-bit output port

– Individual bit set/reset capability

– Outputs can be programmed to be status/interrupt signals

• Versatile interrupt system

– Single interrupt output with eight maskable interrupting conditions

– Interrupt vector output on interrupt acknowledge

– Output port can be configured to provide a total of up to six separate wire-ORable interrupt outputs

• Maximum data transfer rates: 1X - 1MB/sec, 16X - 125kB/sec

• Automatic wake-up mode for multidrop applications

• Start-end break interrupt/status

• Detects break which originates in the middle of a character

• On-chip crystal oscillator

• Single +5V power supply

• Commercial and industrial temperature ranges available

• DIP and PLCC packages