CH340 USB to TTL Serial Adapter – User’s Guide

Overview

The CH340 adapter enables USB-to-UART communication, ideal for flashing firmware, serial debugging, and interfacing microcontrollers (e.g., ESP32, STM32, ATtiny85, Arduino). It’s a cost-effective alternative to FTDI and PL2303 adapters.

Feature	Description
Chipset	WCH CH340G or CH340C
Voltage Levels	Typically supports 3.3V and 5V (through onboard jumper)
Interface	USB Type-A to 6 pin TTL header (5V, VCC, 3.3V, TXD, RXD, GND)
Baud Rate Support	Up to 2 Mbps (typical use: 9600–115200 bps)
OS Compatibility	Windows, macOS, Linux (driver-dependent)

---

Pinout Reference

Pin Label	Function	Notes
5V VCC 3V3	5V Logic Power output (3.3V or 5V) 3.3V Logic	via jumper via jumper via jumper
TXD	Transmit data (from adapter)	Connect to RX of target
RXD	Receive data (to adapter)	Connect to TX of target
GND	ground	common ground

 

Confirm voltage level before connecting to avoid damaging your MCU.

 

---

Driver Installation

Windows

1. Download official driver from WCH website.
2. Install and reboot.
3. Check Device Manager → Ports (COM & LPT) → “USB-SERIAL CH340”.

macOS

• macOS 10.13+ may require signed drivers. Use open-source alternatives.

Linux

• Built-in kernel support via ch341 module.
• Confirm with: dmesg | grep ch341 after plugging in.

---

🔧 Wiring and Setup

Example: Connecting to ESP32/STM32/Arduino

Adapter Pin	Target MCU Pin
TXD	RX
RXD	TX
GND	GND
VCC (Jumper via 3.3V or 5V)

 

---

Serial Communication

Use any serial terminal (e.g., PuTTY, Tera Term, CoolTerm, Arduino IDE):

1. Select correct COM port.
2. Set baud rate (e.g., 115200).
3. Choose 8-N-1 (8 data bits, no parity, 1 stop bit).
4. Disable flow control (needs RTS/DTR).

---

Troubleshooting

Symptom	Cause & Fix
No COM port detected	Driver missing or unsigned – reinstall or try alternate driver
Garbage serial output	Baud rate mismatch or incorrect wiring (TX/RX swapped)
Device resets on TX	Voltage mismatch (Choose the correct voltage with the Jumper)
Works on Linux but not Windows	Windows driver conflict – uninstall old drivers, use official installer

---

Advanced Use

• Level Shifting: Choose the correct voltage with the Jumper

Was this article helpful?

0 0

Please Share Your Feedback

How Can We Improve This Article?

Name

Email

Submit