SCN2681

General description

The Philips Semiconductors SCN2681 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 interfaces directly with microprocessors and may be used in a polled or interrupt driven system.

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 quadruply 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 buffer of the receiving device is full.

Also provided on the SCN2681 are a multipurpose 7-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.

The SCN2681 is available in three package versions: 40-pin and 28?pin (both 0.6? wide) DIPs, and a 44-pin PLCC.

Features

• 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 115.2 k baud
• 16-bit programmable Counter/Timer
• Non-standard rates to 115.2 kb
• One user-defined rate derived from programmable timer/counter
• 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
• Multi-function programmable 16-bit counter/timer
• Multi-function 7-bit input port
• Can serve as clock or control inputs
• Change of state detection on four inputs
• 100 kOhm typical pull-up resistor
• 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
• Output port can be configured to provide a total of up to six separate wire-ORable interrupt outputs
• Maximum data transfer: 1X ? 1 MB/sec; 16X ? 125 kB/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 +5 V power supply
• Commercial and industrial temperature ranges available
• DIP and PLCC packages

Applications

Related applications
Cellular phone - MMS functionality
LCD TV - MMS functionality
Set-top box - MMS functionality

Block diagrams/pinning

Design support

Application Notes

AN10251_2; Automatic '485' turn-around (27-Oct-03)

AN10307_2; UART to Bluetooth interfacing (11-Aug-04)

AN10320_1; Addressing migrations of SCN devices to more advanced technologies (29-Jun-04)

AN10353_1; Application of UART in GPS navigation system (01-Mar-05)

AN405_2; SCN2681/SCN68681 And SCC2691 Data Communications (21-Sep-98)

AN413_2; Using The Datacomm Product's On-Chip Oscillator (02-Oct-88)

Support Documents

EXTBDRT_2; Extended baud rates for SCN2681, SCN68681, SCC2691, SCC2692, SCC68681 and SCC2698B (1991-04-04)

75010337; Philips Innovative Uart Solutions Brochure (2002-12-19)

75014624; Philips industrial and 16C UARTs selection guide (2005-06-01)

Print / Email

• Print this information
• Email this information

Disclaimer

The information published on product information pages of the www.nxp.com or www.semiconductors.com websites is an extract from product data sheets and is for information purposes only. For detailed information please check the most recent version of the relevant product data sheet as published on these websites. In the event of any conflict between product information pages and data sheets or deviations from information provided in the product data sheets on these product information pages, the information provided in the product data sheets shall prevail.

The product status of the product(s) described in the product data sheet may have changed since publication of the data sheet and therefore information in datasheets on product status may be outdated. The latest information on product status is published on the product information pages of the above-mentioned websites.

As from October 1st, 2006 Philips Semiconductors has a new trade name - NXP Semiconductors, which will be used in future data sheets together with new contact details. In data sheets where the previous Philips references remain, please use the new links as shown below.

http://www.philips.semiconductors.com use http://www.nxp.com

http://www.semiconductors.philips.com use http://www.nxp.com (Internet)

sales.addresses@www.semiconductors.philips.com use salesaddresses@nxp.com (e-mail)

The copyright notice at the bottom of each page (or elsewhere in the document, depending on the version)
- © Koninklijke Philips Electronics N.V. (year). All rights reserved -
is replaced with:
- © NXP B.V. (year). All rights reserved.-

If you have any questions related to the data sheet, please contact our nearest sales office via e-mail or phone (details via salesaddresses@nxp.com). Thank you for your cooperation and understanding.