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CH340 driver: Windows does not see the USB-serial adapter

CH340 is a small chip that connects Arduino-style boards, USB adapters and programmers to a PC. Windows usually does not install its driver by itself: you plug the board in, Device Manager shows a nameless “USB2.0-Serial”, and no COM port appears (a COM port is the virtual socket programs use to talk to the board). The driver itself is alive and current - the chip maker updated it in 2025 - so this is a five-minute fix.

Why this happens

  • Windows ships no built-in CH340 driver, so the board stays an unknown device.
  • The USB cable is charge-only - it powers the board but carries no data. Very common with cables that came with power banks.
  • The driver was installed once, but a Windows reinstall wiped it.

Quick checks first

1Try another cable - one that carries data

Charge-only cables are the top reason a board “is not seen”. If the board's light is on but nothing new appears in Device Manager at all, suspect the cable first.

2Find the board in Device Manager

Press Win+X → Device Manager - the list of every device Windows sees. A fresh CH340 shows up as “USB2.0-Serial” with a warning icon. That entry is your board.

A nameless “USB2.0-Serial” with the Hardware ID USB\VID_1A86&PID_7523 is the CH340 - and the whole fix is installing its driver.

Drivers most often behind this problem

Fixing it manually

Install the maker's driver

  1. Open the CH340 page in our catalog - eight versions, the newest from July 2025, from the chip maker WCH.
  2. Run the installer, then unplug and replug the board.
  3. Device Manager now shows “USB-SERIAL CH340 (COM3)” or similar - that means it works.

Point your program at the right port

  1. The number in brackets - COM3, COM4 - is the port your board received.
  2. Pick that port in Arduino IDE (Tools → Port) or in your terminal program, and the board answers.

Know the exact device model?

Search by the Hardware ID USB\VID_1A86&PID_7523, or simply by CH340.

Right-click the nameless device → Properties → Details → Hardware Ids. If the top line reads USB\VID_1A86&PID_7523, it is a CH340.

Try for example: USB\VID_1A86&PID_7523 · read the Hardware ID guide · or browse the driver category

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Frequently asked questions

▸The board blinks and charges, but the PC shows nothing at all.

Almost certainly the cable has no data lines, or a hub is in the way. Take a known-good data cable and plug the board straight into the computer.

▸Which COM port is my board on?

The number in brackets next to “USB-SERIAL CH340” in Device Manager. If several ports are listed, unplug the board and watch which entry disappears and comes back.

▸My adapter says CH341 - is that the same driver?

A sibling chip from the same maker. The same driver package covers both.

Other common problems