SCC68681

General description

The Philips Semiconductors SCC68681 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. It is manufactured in a CMOS process.

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 16× clock derived from a programmable counter/timer, or an external 1× or 16× 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 overrun 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 SCC68681 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/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 kbaud
• Non-standard rates to 115.2 kb
• Non-standard user-defined rate derived from programmable counter/timer
• External 1× or 16× 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
• 100 kOhm typical pull-up resistors
• Multi-function 8-bit output port
• Individual bit set/reset capability
• Outputs can be programmed to be status/interrupt/DMA signals
• Auto 485 turn-around
• 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: 1× = 1 MB/sec; 16× = 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

Products/packages

Pricing/ordering/availability

Applications

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

Block diagrams/pinning

Design support

Application Notes

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

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

Support Documents

75013484; Industrial UART Product and 16CxxxB UART Product Line Card (2005-01-04)

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

Parametrics/similar products

Similar products
SCC68681 links to the similar products page containing an overview of products that are similar in function or related to the type number(s) as listed on this page. The similar products page includes products from the same catalog tree(s), relevant selection guides and products from the same functional category.

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