Philips Semiconductors
Product data sheet
Dual UART
SC28L202
DESCRIPTION
• Three character recognition system per channel, used as:
– General purpose character recognition
The 28L202 is a high performance dual UART. Its functional and
programming features closely match but greatly extend those of
previous Philips dual channel UARTs. Its configuration on power up
is similar that of the SC26C92. Its differences from the SC26C92
are: 256-character receiver, 256 character transmit FIFOs, 3 V and
5 V compatibility, 8 I/O ports for each UART—16 total, arbitrating
interrupt system and overall faster bus and data speeds. It is
fabricated in an advanced 0.5 micron CMOS process.
– Xon/Xoff character recognition
– Address recognition Wake up (multi-drop or ‘9 bit’) mode
– System provides 4 levels of automation on a recognition event
• Programmable data format
– 5 to 8 data bits plus parity and 9 bit mode
– Odd, even, no parity or force parity
– 9/16,1, 1.5 or 2 stop bits
It is a member of the IMPACT line of Data Communications parts
Pin programming will allow the device to operate with either the
Motorola or Intel bus interface by changing the function of some pins
(reset is inverted, DACKN, and IACKN enabled for example).
• 16-bit programmable Counter/Timer
• Programmable baud rate for each receiver and transmitter
selectable from:
The Philips Semiconductors 28L202 Dual Universal Asynchronous
Receiver/Transmitter (DUART) is a single-chip CMOS-LSI
communications device that provides two full-duplex asynchronous
receiver/transmitter channels in a single package. It interfaces
directly with microprocessors and may be used in a polled or
interrupt driven system. The use of the Interrupt system provides
intelligent interrupt vectors.
– 27 fixed rates: 50 to 2.0 Meg baud (includes MIDI rate)
– Other baud rates via external clocks and C/T
– Programmable user-defined rates derived from a programmable
Counter/timer
– External 1X or 16X clock
• Parity, framing, and overrun error detection
• Line break detection and generation; false start bit detection
The operating mode and data format of each channel may be
programmed independently. Additionally, each receiver and
transmitter can select its operating speed as one of twenty-seven
fixed baud rates; a 16X clock derived from one of two programmable
counter/timers, 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 and bridges.
• Programmable channel mode
– Normal (full-duplex)
– Automatic echo
– Local loop back
– Remote loop back
– Multi-drop mode (also called ‘wake-up’ or ‘9-bit’)
Each receiver and transmitter is buffered by 256 character FIFOs to
nearly eliminate the potential of receiver overrun, transmitter
underrun and to reduce interrupt overhead in interrupt driven
systems. In addition, a flow control capability (Xon/Xoff and
RTS/CTS) is provided to disable a remote transmitter when the
receiver buffer is full.
• Multi-function 8 bit I/O input port per channel loosely assigned to
each channel.
– Can serve as clock or control inputs
– Change of state detection on eight inputs
– Inputs have typically >100 MΩ pull-up resistors
– Modem and DMA interface
Also provided on the 28L202 is a multipurpose 8-bit I/O for each
channel. These can be used as general-purpose I/O ports or can be
assigned specific functions (such as clock inputs or status and
interrupt outputs) under program control. Normally they will be used
for modem control and DMA interface. All ports have change of state
detectors and input sections are always active making output
signals available to the internal circuits and the control processor.
• Versatile arbitrating interrupt system
– Interrupt system totally supports ‘single query’ polling
– Output port can be configured to provide a total of up to six
separate interrupt type outputs that may be wire-ORed
(switched to open drain).
– Each FIFO can be independently programmed for any of 256
interrupt levels
The 28L202 is available in a 52–pin TSSOP package. For other
package options, contact Philips.
– Watch dog timer for each receiver
• Maximum data transfer rates: 1X – 3 Mb/sec, 16X – 2 Mb/sec
• Automatic wake-up mode for multi-drop applications
• Start-end break interrupt/status
FEATURES
• Member of IMPACT family: 3.3 V to 5.0 V , –40°C to +85°C and
80xx or 68k bus interface (I/M modes) for all devices.
• Detects break which originates in the middle of a character
• On-chip crystal oscillator
• Bit-by-bit real time transmission error check for high data integrity
systems.
• Dual full-duplex independent asynchronous receiver/transmitters
• 256 character FIFOs for each receiver and transmitter
• Power down mode at less than 10 µa
• Receiver time-out mode
• Powers up to 9600 baud, 1 stop bit, no parity, 1 stop bit, interrupt
• Single +3.3V or +5V power supply
disabled, all I/O set to input.
• Pin programming to 68K or 80xxx bus interface
1
2005 Nov 01
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