Philips Semiconductors
Dual asynchronous receiver/transmitter (DUART)
Product specification
SCC68692
DESCRIPTION
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. In addition, a flow control capability is provided to disable
a remote DUART transmitter when the receiver buffer is full.
Also provided on the SCC68692 are a multipurpose 6-bit input port
and a multipurpose 8-bit output port. These can be used as general
purpose I/O ports or can be assigned specific functions (such as
clock inputs or status/interrupt outputs) under program control.
FEATURES
• S68000 bus compatible
• Dual full-duplex asynchronous receiver/transmitters
• Quadruple buffered receiver data register
• 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
• 16-bit programmable Counter/Timer
• 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
• 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
– Multidrop mode (also called ‘wake-up’ or ‘9-bit’)
• Multi-function 6-bit input port
– Can serve as clock or control inputs
– Change of state detection on four inputs
– Inputs have typically >100k 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
• Power down mode
• Receiver timeout mode
• Commercial and Industrial temperature range versions
• TTL compatible
• Single +5V power supply
ORDERING INFORMATION
DESCRIPTION
40-Pin (600 mils wide) Ceramic Dual In-Line Package (Cerdip)
40-Pin (600 mils wide) Plastic Dual In-Line Package (DIP)
44-Pin Plastic Leaded Chip Carrier (PLCC)
COMMERCIAL
VCC = +5V +10%,
TA = 0 to +70°C
SCC68692C1F40
SCC68692C1N40
SCC68692C1A44
INDUSTRIAL
VCC = +5V +10%,
TA = -40 to +85°C
SCC68692E1F40
SCC68692E1N40
SCC68692E1A44
DWG #
0590B
SOT129-1
SOT187-2
1998 Sep 04
2
853–0977 19971