CH340 drivers
What is the CH340?
The CH340 is a small chip that converts USB into a serial (UART) connection. Many of our boards use one so that a single USB-C cable can both power the board and carry the serial connection your computer needs to upload code and read Serial output.
Your computer needs a driver to talk to that chip. Windows and macOS do not include one, so on a fresh machine the board plugs in, gets power, and still does not appear as a port in the Arduino IDE or Thonny. Nothing is broken — the driver just is not there yet.
Do I need this?
Plug the board in and check what your computer already thinks it is.
On Windows, open Device Manager (right-click the Start button → Device Manager):
| What you see | What it means |
|---|---|
| Ports (COM & LPT) → USB-SERIAL CH340 (COM5) | The driver is installed. Nothing to do — use that COM port. |
| Other devices → USB Serial, with a yellow warning triangle | The chip is there but has no driver. Follow the Windows steps below. |
| Nothing appears or disappears when you plug in | Not a driver problem. Try another USB-C cable, then another USB port. |
To be certain which chip you have, right-click the device → Properties → Details → Hardware Ids. A CH340 reports a hardware ID beginning with USB\VID_1A86, where VID_1A86 is WCH, the manufacturer of the chip.
On macOS, the board shows up as /dev/cu.wchusbserial* once the driver is installed. On Linux, it appears as /dev/ttyUSB0 with no driver installation needed.
Windows
CH341SER driver for Windows
Official WCH driver installer. Covers the whole CH340 and CH341 family.
- Download and run the installer from the link above.
- Click Install and wait for the success message.
- Unplug the board and plug it back in. This step matters — see the note below.
- Check Device Manager again. The board should now be listed under Ports (COM & LPT) with a COM number.
The driver installed, but the board still is not detected
Installing a driver adds it to Windows' driver store; it does not always attach it to a device that Windows has already given up on. If the board is still sitting under Other devices after installing:
- Unplug the board and plug it back in. This is enough most of the time.
- If it is still there, right-click it → Update driver → Search automatically for drivers.
- If it is still there, right-click it → Uninstall device, then unplug and replug.
macOS
CH340 driver for macOS
Official WCH CH34x serial driver download for macOS
Download the package, open the .dmg and follow the installer.
Linux
The CH340 driver is part of the kernel, so there is nothing to install. The board appears as /dev/ttyUSB0 (or ttyUSB1, and so on) as soon as you plug it in.
If the port exists but you get a permission error when uploading, add yourself to the group that owns serial ports, then log out and back in:
sudo usermod -a -G dialout $USER
brltty service, which supports braille displays, claims CH340 devices and makes the port vanish a second or two after you plug the board in. If that is happening, sudo apt remove brltty frees the port.Which boards use a CH340?
Not all of them do — some of our boards connect over the microcontroller's own USB hardware and need no driver at all. If you are unsure, check the Hardware details page for your board, or use the Device Manager check above, which tells you what the board actually is rather than what it ought to be.