INTEGRATED CIRCUITS SCC2681T Dual asynchronous receiver/transmitter (DUART) Product data 2004 Apr 06 Philips Semiconductors Product data Dual asynchronous receiver/transmitter (DUART) SCC2681T DESCRIPTION Programmable baud rate for each receiver and transmitter The Philips Semiconductors SCC2681 Dual Universal selectable from: Asynchronous Receiver/Transmitter (DUART) is a single-chip 22 fixed rates: 50 to 115.2 k baud MOS-LSI communications device that provides two independent Non-standard rates to 115.2 full-duplex asynchronous receiver/transmitter channels in a single Non-standard user-defined rate derived from programmable package. The SCC2681T features a faster bus cycle time than the counter/timer standard SCC2681. The quick bus cycle eliminates or reduces the need for wait states with fast CPUs and permits high throughput in External 1 or 16 clock I/O intensive systems. Higher external clock rates may be used with Parity, framing, and overrun error detection the transmitter, receiver and counter timer which in turn provide greater versatility in baud rate generation. The SCC2681T interfaces False start bit detection directly with microprocessors and may be used in a polled or Line break detection and generation interrupt driven system. It is manufactured in CMOS technology. Programmable channel mode The operating mode and data format of each channel can be Normal (full-duplex) programmed independently. Additionally, each receiver and transmitter can select its operating speed as one of eighteen fixed Automatic echo baud rates, a 16 clock derived from a programmable counter/timer, Local loopback or an external 1 or 16 clock. The baud rate generator and Remote loopback counter/timer can operate directly from a crystal or from external clock inputs. The ability to independently program the operating Multi-function programmable 16-bit counter/timer speed of the receiver and transmitter make the DUART particularly Multi-function 7-bit input port attractive for dual-speed channel applications such as clustered Can serve as clock or control inputs terminal systems. Change of state detection on four inputs Each receiver is quadruple buffered to minimize the potential of 100 k typical pull-up resistors receiver over-run or to reduce interrupt overhead in interrupt driven systems. In addition, a flow control capability is provided to disable a Multi-function 8-bit output port remote DUART transmitter when the receiver buffer is full. Individual bit set/reset capability Also provided on the SCC2681T are a multipurpose 7-bit input port Outputs can be programmed to be status/interrupt/DMA signals and a multipurpose 8-bit output port. These can be used as general Auto 485 turn-around purpose I/O ports or can be assigned specific functions (such as Versatile interrupt system clock inputs or status/interrupt outputs) under program control. Single interrupt output with eight maskable interrupting For a complete functional description and programming information conditions for the SCC2681T, refer to the SCC2681 product specification. Output port can be configured to provide a total of up to six separate wire-ORable interrupt outputs FEATURES Maximum data transfer rates: Fast bus cycle times reduce or eliminate CPU wait states 1 1 MB/sec transmitter and receiver 16 500 kB/sec receiver and 250 kB/sec transmitter Dual full-duplex asynchronous receiver/transmitters Automatic wake-up mode for multidrop applications Quadruple buffered receiver data registers Start-end break interrupt/status Programmable data format 5 to 8 data bits plus parity Detects break which originates in the middle of a character Odd, even, no parity or force parity On-chip crystal oscillator 1, 1.5 or 2 stop bits programmable in 1/16-bit increments Single +5 V power supply 16-bit programmable Counter/Timer Commercial temperature range ORDERING INFORMATION DESCRIPTION V = +5 V 10%, T = 0 C to +70 C DWG CC amb 44-Pin Plastic Lead Chip Carrier (PLCC) SCC2681TC1A44 SOT187-2 NOTE: For a full register description and programming information see the SCC2681. 2004 Apr 06 2