USB Bridge Controller CH341


CH341 is a USB bus converter chip which converts USB to serial port, printer port, parallel port, and common 2/4-line synchronize serial communication interfaces etc.

In UART mode, CH341 provides UART transmit enable, UART receive ready rate control signals, etc., and standard MODEM interface signals, used to expand serial port for computer or upgrade directly normal serial device to USB bus.

In printer port mode, CH341 provides a standard USB print port compatible with USB-related specifications and the Windows operating system for upgrading a print port printer directly to the USB. In parallel port mode, CH341 provides an 8-bit parallel interface in EPP mode or MEM mode for input and output data directly without a microcontroller/DSP/MCU.

In addition, CH341B/F/A support commonly used synchronous serial interface such as 2-line interface (SCL line, SDA line) and 4-line interface (CS line, SCK/CLK line, MISO/SDI/DIN Line, MOSI/SDO/DOUT line), etc.


2.1. Introduction

  • Full speed USB device interface, USB 2.0 compatible.
  • Supports 5V and 3.3V power supply voltages.
  • Optional: customize the vendor ID, product ID, serial number, etc. via an external low-cost serial EEPROM.
  • Low cost, convert the original serial port peripheral devices, the original print port printer, and the original parallel port peripheral devices to USB directly.
  • RoHS compliant SOP-28, SSOP-20 and QFN28 lead-free package.
  • Only compatible with the applications, and cannot be absolutely the same.

2.2. UART

  • Emulate standard UART interface, used to upgrade the original serial peripheral or expand additional UART via USB.
  • Original UART applications are totally compatible without any modification in Windows operating systems.
  • Hardware full duplex UART interface, integrated transmit-receive buffer, supports communication baud rate varies from 50bps to 2Mbps.
  • UART supports 5, 6, 7 or 8 data bits, and supports odd, even, space, mark and none parity.
  • Supports UART transmit enable, UART receive ready rate control signals and so on, and common MODEM interface signals.
  • Provides further RS232, RS485, RS422 interface, etc. through external voltage conversion chip.
  • Supports access to the CH341 external serial EEPROM memory in UART communication.

2.3. Printer Port

  • Standard USB print port for upgrading the original print port printer, compatible with the relevant USB specifications.
  • Compatible with Windows/Linux/MACOS and so on, and the application is fully compatible.
  • Supports various standard print port printers, optional low speed printing and high speed printing.
  • Supports two-way communication of the IEEE-1284 specification and supports one-way and two-way transmission of printers.

2.4. Parallel Port

  • Two modes are available: EPP mode and MEM mode.
  • EPP provides signals such as AS#, DS# and WR# etc. Similar to EPP V1.7 or EPP V1.9.
  • The MEM mode provides signals such as A0, RD# and WR# etc. Which is similar to the memory read/write mode.

2.5. Synchronous serial port

  • FlexWireTM technology, enables flexible 2-line to 5-line synchronous serial ports through software.
  • As a Host/Master host, it supports common synchronous serial interfaces such as 2-line and 4-line.
  • The 2-line interface provides two signal lines SCL and SDA, and supports 4 transmission speeds.


Note: CH341C/T is only used for USB to serial port or USB to 2-line interface.

CH341H is only used for USB to 4-line interface, etc. (such as SPI). New designs are not recommended. CH341B or CH341F is recommended.

CH341A, CH341T and CH341H must be connected with crystal and oscillation capacitor.

CH341B, CH341F and CH341C can choose to connect external crystal and capacitor, or choose not to connect externally and directly use the built-in clock.

relation files

file name file content
CH341SER.EXE CH340/CH341 USB to serial port Windows driver, supports Windows XP/Vista/7/8/8.1/10/11/ SERVER 2003/2008/2012/2016/2019/2022 -32/64bit, Microsoft WHQL Certified, supports USB to 3-line and 9-line serial port. Used to distribute to user with the product.
CH340DS1.PDF CH340 datasheet, USB bus converter chip which converts USB to serial port, printer port, IrDA SIR etc. Integrated clock, supports various operating systems, chip information can be customized, this datasheet is about USB to serial port and USB to Infrared Adapter SIR.
CH432DS1.PDF CH432 datasheet. Dual-UART expander. Compatible with 16C550. 8-bit parallel port or SPI to UART. Each UART receive/transmit data independently. Up to 4Mbps baud rate. Can be used for MCU dual-UART expansion. CH432 supports full-duplex/half-duplex/infrared modes.
CH315DS1.PDF CH315 datasheet. CH315G is a USB1.1 extension cable control chip. The extension distance of network cable can be up to 300 meters. CH315H is a USB signal isolation control chip, used for optoelectronic isolator.
CH438DS1.PDF CH438 datasheet. CH438 is an 8-UART extension chip. Each UART receive/transmit has independent 128-byte FIFO. The maximum baud rate is 4Mbps. It supports hardware flow control, compatible with 16C550/16C750. It provides 8-bit parallel interface, used for MCU 8-UART extension.
CH341SER_ANDROID.ZIP CH340/CH341 USB to serial port Android free drive application library, for Android OS 3.1 and above version which supports USB Host mode already, no need to load Android kernel driver, no root privileges. Contains apk, lib library file (Java Driver), App Demo Example (USB to UART Demo SDK).
CH9340DS.PDF CH9340 datasheet, USB CDC to single serial port, built-in crystal oscillator, supports built-in CDC driver in operating system.