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Thursday, September 10, 2020

Designing a USB to UART Module Board using CH340G

Overview

CH340 is a series of USB to UART converter IC. There are six options within this family. This chip is popular within some Arduino board, nodeMCU board module etc. I bought five of CH340G for my own esp8266 firmware flushing board in 2019 for a few Dollars. Finally it works well.

A commercial sample of CH340G

Various CH340 chips pins diagram

The USB version of this chip is USB 2.0 . It's supply from both 3.3V or 5V source. Data transmission could take up to 2 Mbps.

Referring to the serial communication, the data rate ranges from 2400bps to 115200bps.

In CH340G there are up to 16 pins. But I show only some important pin to know in this this design.

  • GND - Supply ground at pin 1
  • TXD - CH340G Transmit at pin 2
  • RXD - CH340G Receive at pin 3
  • V3 - Regulated +3.3V supply voltage
  • D+ - Data+ 
  • D- - Data-
  • XI and XO - 12MHz crystal pins
  • V5 - +5V supply voltage

Other remanding pins are serial port pin functions that I don't want show them here due to a rich of web-based resources.

Schematic And PCB Design

In this design I make a very simple USB to UART converter with only Transmit (Tx) and Receive (Rx) pin. The design  works at 5V.



Since in the EDA software I use for design doesn't have CH340 chip. So I made my own symbol following the original device pins diagram from the vendor. This video shows about the process of making a symbol of CH340 for schematic design.



 

I use a USB type-B connector for USB to Host communication due to the stock components I stock.

Designing a USB to UART Module Board using CH340G
Schematic Diagram

Designing a USB to UART Module Board using CH340G
PCB design view

Designing a USB to UART Module Board using CH340G
PCB pattern
Designing a USB to UART Module Board using CH340G
Component side

Designing a USB to UART Module Board using CH340G
A 3D View of this design

Click here if you wish to download a zip of this Proteus 8 design. This video shows about the schematic and PCB design.




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