The UPD8251AF is a Programmable Communication Interface (USART) designed for serial data communication. Manufactured by NEC, it's a versatile device that supports both synchronous and asynchronous communication protocols. It's commonly used to interface microprocessors and microcontrollers with serial devices such as modems, printers, and other peripherals.

Applications

• Serial Communication: Interfacing microprocessors with serial devices such as modems, printers, and other peripherals.
• Computer Peripherals: Connecting computers to serial printers, terminals, and other legacy devices.
• Data Acquisition Systems: Implementing serial communication links for data acquisition and control systems.
• Industrial Control: Used in industrial control systems for serial communication between controllers and remote devices.
• Networking: Implementing serial communication protocols in networking applications.

Features

• Programmable Baud Rate: Supports a wide range of programmable baud rates for flexible communication.
• Synchronous and Asynchronous Modes: Operates in both synchronous and asynchronous communication modes.
• Full-Duplex Operation: Supports full-duplex communication, allowing simultaneous transmission and reception.
• Error Detection: Includes error detection capabilities such as parity checking and framing error detection.
• Data Length Selection: Supports programmable data length (5-8 bits) for compatibility with various devices.
• Interrupt-Driven Operation: Can be configured for interrupt-driven operation, enabling efficient handling of serial data.

Benefits

• Versatile Communication: Supports both synchronous and asynchronous communication protocols for flexible interfacing.
• Flexible Baud Rate: Programmable baud rate allows for compatibility with a wide range of serial devices.
• Efficient Data Transfer: Full-duplex operation enables simultaneous transmission and reception, maximizing data throughput.
• Reliable Data Transmission: Error detection capabilities ensure reliable data transmission and reduce errors.
• Simplified Interface: Provides a simplified interface between microprocessors and serial devices.

Additional Details

The UPD8251AF requires a clock signal for operation. The baud rate is determined by a programmable divider. It utilizes control registers for configuring the communication parameters, such as baud rate, data length, parity, and mode. The device communicates with the microprocessor through a data bus and control signals. It is typically used with a UART driver in software to manage the serial communication process. The device is often used in legacy systems and can be found in older computer peripherals and industrial equipment.