The XR68C681P is a Dual Universal Asynchronous Receiver/Transmitter (DUART) manufactured by Exar Corporation (formerly Sipex). It's designed to provide two independent serial communication channels in a single IC. This DUART is commonly used in embedded systems and communication devices where multiple serial ports are required. It supports various features, including programmable baud rates, interrupt control, and modem control signals, making it a versatile solution for serial communication applications.

Applications:

• Embedded systems: Provides serial communication ports for microcontrollers and embedded processors.
• Point-of-sale (POS) systems: Connects to serial peripherals such as barcode scanners, printers, and scales.
• Industrial automation: Interfaces with serial devices in industrial control systems.
• Networking equipment: Enables serial communication between network devices.
• Data acquisition systems: Collects data from serial sensors and instruments.

Features:

• Dual UART: Provides two independent serial communication channels.
• Programmable baud rates: Supports a wide range of baud rates.
• Interrupt control: Generates interrupts for various events, such as data reception and transmission completion.
• Modem control signals: Supports modem control signals (CTS, RTS, DSR, DTR, DCD, RI) for modem communication.
• FIFO buffers: Includes FIFO buffers for transmit and receive data.

Benefits:

• Reduced component count: Provides two serial ports in a single IC, saving space and cost.
• Flexible communication: Supports a wide range of baud rates and communication protocols.
• Efficient interrupt handling: Interrupt control simplifies software development.
• Modem support: Enables communication with modems and other serial devices.
• Improved data throughput: FIFO buffers improve data throughput and reduce CPU overhead.

The XR68C681P supports various data formats, including different word lengths, parity options, and stop bits. Each UART channel can be configured independently, allowing for flexible communication with different serial devices. The device includes programmable interrupt sources, which can be enabled or disabled to suit the specific application requirements. It also features loopback mode for diagnostic testing. Proper termination and signal conditioning may be required to ensure reliable communication, especially at high baud rates.

Technical Specifications (Typical):

• Number of UART Channels: 2
• Data Rates: Up to 1 Mbps (or higher, depending on the specific version)
• Data Bits: 5, 6, 7, or 8
• Parity: Odd, Even, None
• Stop Bits: 1 or 2
• Operating Voltage: 5V
• Operating Temperature: -40°C to +85°C