INTEGRATED CIRCUITS SC28L91 3.3 V or 5.0 V Universal Asynchronous Receiver/Transmitter (UART) Product data sheet 2004 Oct 21 Supersedes data of 2000 Sep 22 Philips Semiconductors Product data sheet 3.3 V or 5.0 V Universal Asynchronous SC28L91 Receiver/Transmitter (UART) DESCRIPTION 16-bit programmable Counter/Timer The SC28L91 is a new member of the IMPACT family of Serial Programmable baud rate for each receiver and transmitter Communications Controllers. It is a single channel UART operating selectable from: at 3.3 V and 5.0 V V , 8 or 16 byte FIFOs and is quite compatible CC with software of the SC28L92 and previous UARTs offered by 28 fixed rates: 50 to 230.4 k baud Philips. It is a new part that is similar to our previous one channel Other baud rates to 1 MHz at 16X part but is vastly improved. The improvements being: 16 character Programmable user-defined rates derived from a programmable receiver, 16 character transmit FIFOs, watch dog timer for the counter/timer receiver, mode register 0 is added, extended baud rate, over all External 1X or 16X clock faster bus and data speeds, programmable receiver and transmitter interrupts and versatile I/O structure. (The previous one channel Parity, framing, and overrun error detection part, SCC2691, is NOT being discontinued.) False start bit detection Pin programming will allow the device to operate with either the Line break detection and generation Motorola or Intel bus interface. Bit 3 of the MR0 register allows the device to operate in an 8-byte FIFO mode if strict compliance with Programmable channel mode an 8-byte FIFO structure is required. Normal (full-duplex) The Philips Semiconductors SC28L91 Universal Asynchronous Automatic echo Receiver/Transmitter (UART) is a single-chip CMOS-LSI Local loop back communications device that provides a full-duplex asynchronous Remote loop back receiver/transmitter channel in a single package. It interfaces directly with microprocessors and may be used in a polled or Multi-drop mode (also called wake-up or 9-bit) interrupt driven system with modem and DMA interface. Multi-function 7-bit input port (includes IACKN) The operating mode and data format of the channel can be Can serve as clock or control inputs programmed independently. Additionally, the receiver and Change of state detection on four inputs transmitter can select its operating speed as one of 28 fixed baud Inputs have typically >100 k pull-up resistors rates a 16X clock derived from a programmable counter/timer, or an Change of state detectors for modem control external 1X or 16X clock. The baud rate generator and counter/timer can operate directly from a crystal or from external clock inputs. The Multi-function 8-bit output port ability to independently program the operating speed of the receiver Individual bit set/reset capability and transmitter make the UART particularly attractive for dual-speed Outputs can be programmed to be status/interrupt signals channel applications such as clustered terminal systems. FIFO status for DMA interface The receiver and transmitter is buffered by 8 or 16 character FIFOs to minimize the potential of receiver overrun, transmitter underrun Versatile interrupt system and to reduce interrupt overhead in interrupt driven systems. In Single interrupt output with eight maskable interrupting addition, a flow control capability is provided via RTS/CTS signaling conditions to disable a remote transmitter when the receiver buffer is full. Output port can be configured to provide a total of up to six DMA interface is and other general purpose signals are provided on separate interrupt outputs that may be wire ORed. the SC28L91 via a multipurpose 7-bit input port and a multipurpose Each FIFO can be programmed for four different interrupt levels 8-bit output port. These can be used as general-purpose ports or Watchdog timer for the receiver can be assigned specific functions (such as clock inputs or status/interrupt outputs, FIFO conditions) under program control. Maximum data transfer rates: 1X 1 Mbit/s, 16X 1 Mbit/s The SC28L91 is available in two package versions: a 44-pin PLCC and 44-pin plastic quad flat pack (PQFP). Automatic wake-up mode for multi-drop applications Start-end break interrupt/status with mid-character break detect. FEATURES On-chip crystal oscillator Member of IMPACT family: 3.3 to 5.0 volt , 40C to +85C and Power-down mode 68K for 80xxx bus interface for all devices. Receiver time-out mode A full-duplex independent asynchronous receiver/transmitter Single +3.3 V or +5 V power supply 16 character FIFOs for each receiver and transmitter Pin programming selects 68K or 80xxx-bus interface 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 2 2004 Oct 21