The UPD8251C is a programmable communication interface (USART) manufactured by NEC. It is designed for synchronous and asynchronous serial data communication. This versatile chip is commonly used to implement serial communication protocols in a variety of embedded systems.

Applications

• Computer serial ports (COM ports): Implementing RS-232 communication for connecting peripherals such as modems, printers, and other serial devices.
• Industrial control systems: Facilitating serial communication between different modules and controllers within an industrial environment.
• Data acquisition systems: Transmitting data from sensors and instruments to a central processing unit.
• Embedded systems: Serving as the serial communication interface in microcontrollers and embedded processors.
• Communication with modems: Handling the serial data exchange between a computer or embedded system and a modem.

Features

• Programmable Serial Communication: Supports both synchronous and asynchronous communication modes.
• Full Duplex Operation: Allows simultaneous transmission and reception of data.
• Baud Rate Generator: Provides a flexible baud rate selection for various communication speeds.
• Error Detection: Includes parity, overrun, and framing error detection capabilities.
• Single +5V Power Supply: Operates on a single 5V power supply, simplifying integration.
• TTL Compatible Inputs/Outputs: Compatible with standard TTL logic levels.
• Programmable Data Format: Supports various data formats including different word lengths and parity options.

Benefits

• Versatile Communication: Can be configured for a wide range of serial communication applications.
• Reduced Component Count: Integrates essential serial communication functions into a single chip.
• Simplified System Design: Simplifies the design of serial communication interfaces in embedded systems.
• Improved Reliability: Built-in error detection helps ensure reliable data transmission.
• Cost-Effective Solution: Provides a cost-effective solution for serial communication needs.

Additional Details

The UPD8251C is typically programmed using control registers to set the desired communication parameters, such as baud rate, data format, and error detection options. Its flexibility and widespread availability made it a popular choice for serial communication applications in the past. It's often used with microcontrollers such as the 8051 family. The chip's status can be read to determine transmission readiness, data availability, and error conditions. Understanding the control and status registers is essential for proper operation.