FakeCH340DriverFixer

Driver fix for fake or counterfeit CH340 chips

Background

Recently (April 2023) a driver update delivered through windows update (3.8.2023.02) is breaking some fake CH340G chips (this chip is used to emulate a USB serial port to communicate with the Arduino main MCU).

This triggers various symptoms as impossible to open the serial port or some crashes depending of the application. Some software still work with it as chip crashes seems to be related to the port settings.

The huge problem is that windows update will reinstall again and again the offending driver, requiring some deeper manipulations to block and keep an older driver.

NB : if you freshly bought your device (Arduino or other devices) running such fake chips, better return it and ask for a refund instead of encouraging keeping fake chips on the market. For others having such chips with expired warranty this workaround is for you.

How to recognise a fake CH340G chip ?

The device will appear as a CH340 in the device manager :

Most of the counterfeit chips are coming unlabelled (it's a rectangular 16 pins chip) :

Most of the counterfeit chips are showing as USB2.0-Ser! instead of USB2.0-Serial from the USB descriptor (used by this utility to determine if the chip is likely to be fake

Requirements

Have one or more CH340 chips actually plugged into the computer
Make sure to close any application using a CH340G serial port
Administrator privileges
Windows driver update enabled

What it does ?

Enumerate CH340 based serial ports and give an estimate if the chip is likely to be fake or genuine.
Install the last known to work driver with fake chips (3.5.2019.1).
Uninstall the driver known not to work driver with fake chips (3.8.2023.02).
Block all pending windows update for CH340 driver (Hide the update in the windows update semantic) : once the driver uninstalled the drivers updates will automatically be pending again allowing to block it.

How to use

Download and decompress the latest release : https://github.com/SHWotever/FakeCH340DriverFixer/releases/latest

Apply fix

Execute directly FakeCH340DriverFixer.exe to automatically fix the drivers.

Revert fix

Execute FakeCH340DriverFixer.exe unblock to revert the windows update changes, then you can use windows update to reinstall the latest driver update.

Limitations

It's not possible to revert reliably the driver only for a specific device instance, windows update will blindly update all of them automatically.
The fixer only targets a specific driver for uninstallation, if the driver gets a new update this fix will have to be updated.
Manipulating windows update might make nervous some Anti-viruses and trigger false positives, you've been warned ;) You have all the source code to check yourself what it does.