SC28C94A1A中文资料四通道通用异步接收器/发送器(QUART)数据手册恩XP规格书

描述 Description

The 28C94 quad universal asynchronous receiver/transmitter (QUART) combines four enhanced Philips Semiconductors industry-standard UARTs with an innovative interrupt scheme that can vastly minimize host processor overhead. It is implemented using Philips Semiconductors' high-speed CMOS process that combines small die size and cost with low power consumption.
The operating speed of each receiver and transmitter can be selected independently at 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 QUART particularly attractive for dual-speed channel applications such as clustered terminal systems.
Each receiver is buffered with eight character FIFOs (first-in-first-out memories) and one shift register to minimize the potential for receiver overrun and to reduce interrupt overhead in interrupt driven systems. In addition, a handshaking capability is provided to disable a remote UART transmitter when the receiver buffer is full. (RTS control)
The 28C94 provides a power-down mode in which the oscillator is stopped and the register contents are stored. This results in reduced power consumption on the order of several magnitudes. The QUART is fully TTL compatible and operates from a single +5V power supply.

特性 Features

New low overhead interrupt control
All commercial parts meet industrial timing and temperature parameters
Four Philips Semiconductors industry-standard UARTs
Eight byte receive FIFO and eight byte transmit FIFO for each UART
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
Baud rate for the receiver and transmitter selectable from: 23 fixed rates: 50 to 230.4K baud; Non-standard rates to 1.0 M baud
User-defined rates from the programmable counter/timer associated with each of two blocks
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 loop back, remote loopback
Programmable interrupt priorities
Identification of highest priority interrupt
Global interrupt register set provides data from interrupting channel
Vectored interrupts with programmable vector format
IACKN and programmable DTACKN signals
Built-in baud rate generator with choice of 18 rates
Four I/O pins per UART for modem controls, clocks, etc.
Power down mode
High-speed CMOS technology
52-pin PLCC package
Commercial and industrial temperature ranges available
On-chip crystal oscillator
TTL compatible
Single +5V power supply with low power mode
Two multifunction programmable 16-bit counter/timers
1MHz 16x mode operation
10ns data bus release time
\"Watch Dog\" timer for each receiver