As modern computers gradually phase out traditional serial ports (RS-232, RS-485), USB (Universal Serial Bus) has become the mainstream interface for connecting computer peripherals. USB to serial converters have emerged to solve the problem of connecting serial devices to modern computers. This article will introduce the basic principles and technical implementation of USB to serial converters.
1. Basic principles of USB to serial converters
1.1 Serial port and USB interface
Serial port: Serial port is a traditional communication interface, commonly used for communication between early computers and external devices. Common serial port types include RS-232, RS-422 and RS-485.
USB interface: USB is a modern universal serial bus with high data transfer rate and plug-and-play features.
1.2 Working principle of converter
Protocol conversion: The core function of USB to serial converter is to convert USB protocol to serial protocol to realize data transmission between different interfaces.
Hardware implementation: usually includes a USB interface chip, a serial port interface chip and some necessary circuits (such as level conversion, clock circuit, etc.).
2. Technical implementation
2.1 Hardware design
USB control chip: responsible for processing the USB protocol stack and managing USB communication. Commonly used chips include FTDI, Prolific, Silicon Labs, etc.
Serial port chip: responsible for processing serial port signals and protocols, usually supporting multiple serial port standards.
Level conversion: in some applications, signals of different levels need to be converted to appropriate levels.
2.2 Software driver
Driver: The corresponding driver needs to be installed in the operating system to identify and manage USB to serial port devices.
Virtual serial port: The driver creates a virtual serial port, allowing applications to access USB to serial port devices in the way of traditional serial ports.