CH340 USB to TTL Module STC MCU Download Cable USB Serial Adapter Flash Board

CH340 USB to TTL module with 3.3V/5V level switching. Ideal for STC MCU downloading, Arduino programming, ESP8266/ESP32 debugging, router flashing. Onboard power and TX/RX LEDs. Plug-and-play, compatible with Windows/Linux/Mac

CH340 USB to TTL Module Application features:

◆ Main Chip
CH340G / CH340C

◆ Interface Type
USB Type-A / Micro USB / Type-C (varies by version)

◆ Output Signal
TTL level (3.3V / 5V switchable)

◆ Pin Definition

• 5V / 3.3V (power output)

• TXD (transmit)

• RXD (receive)

• GND (ground)

◆ Baud Rate
50bps – 2Mbps

◆ Onboard Indicators

• Power LED (PWR)

• TXD transmit LED

• RXD receive LED

◆ Jumper Functions

• 3.3V / 5V level switching

• Power supply selection

◆ Typical Applications

• STC MCU program download

• Arduino programming

• ESP8266 / ESP32 debugging

• Router / set-top box flashing

• Serial debugging assistant

• GPS module data reading

• MCU serial communication

◆ Key Advantages

Low cost, good stability

3.3V/5V level compatible

Driver-free (Windows 10/11 auto-recognize)

TX/RX LEDs for easy debugging

Plug-and-play

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FAQ

1. What is the CH340 USB to TTL Module?
The CH340 USB to TTL module is a USB-to-serial adapter based on the CH340 series chip from WCH (Nanjing Qinheng Microelectronics). Its core function is to convert USB protocol to UART serial communication protocol (TTL level), enabling seamless communication between a computer's USB port and a microcontroller's serial port. It is commonly used for programming and serial debugging of STC, STM32, Arduino, and other microcontrollers.

2. What are the key specifications of the CH340 module?
Key specifications include:

• Chip: CH340G / CH340C / CH340N, etc.

• Operating Voltage: Supports both 3.3V and 5V (selectable via jumper)

• Baud Rate: Supports up to 2 Mbps (typical use: 9600–115200 bps)

• Interface: USB Type-A to TTL header (VCC, 3.3V, TXD, RXD, GND)

• Indicator LEDs: Power LED (PWR) + TXD/RXD data indicator LEDs

• Dimensions: Approx. 33mm × 16mm

• OS Compatibility: Windows, macOS, Linux

3. What is the pinout of the CH340 module?
The standard module pinout is as follows:

⚠️ Note: TXD and RXD must be cross-connected — module TXD → device RXD, module RXD → device TXD.

4. How do I install the CH340 driver?

• Windows: Download the CH341SER.EXE driver from the official WCH and install. After installation, check Device Manager → Ports (COM & LPT) for "USB-SERIAL CH340".

• macOS: macOS 10.13+ may require signed drivers; open-source drivers are available.

• Linux: Built-in kernel support via the ch341 module 

5. How do I select 3.3V or 5V on the CH340 module?
The module typically uses a jumper or shunt to select the output voltage. Considerations:

• For 5V systems (e.g., STC89C52, 51-series MCUs), select 5V.

• For 3.3V systems (e.g., ESP32, STM32), select 3.3V.

• ⚠️ Critical warning: If the CH340 is powered at 3.3V, do not connect it to a 5V system — this will damage the chip.

6. How do I connect the CH340 module to a microcontroller for programming?
Using an STC microcontroller as an example:

1. Module TXD → MCU RXD (P3.0)

2. Module RXD → MCU TXD (P3.1)

3. Module GND → MCU GND

4. Select 3.3V or 5V power based on the MCU's voltage

STC microcontrollers require a "cold start" — after clicking "Download" in the STC-ISP software, you must disconnect and reconnect the MCU's power (or GND). Some advanced modules support auto cold-start without manual power cycling.

7. What should I do if the CH340 module shows a yellow exclamation mark in Device Manager?
This usually indicates driver issues or driver conflicts. Solutions:

1. Download the latest CH340/CH341 driver

2. Uninstall old drivers and reinstall.

3. Try a different USB port or USB cable.
   

8. Why am I getting garbage characters during serial communication?
Common causes and solutions:

1. Baud rate mismatch: Check that the terminal software (e.g., PuTTY, SSCOM) baud rate matches the target device (commonly 115200).

2. TXD/RXD swapped: Confirm module TXD → device RXD, module RXD → device TXD.

3. Voltage mismatch: Confirm the module output voltage matches the target device level.

4. Incorrect serial settings: Typically use 8-N-1 (8 data bits, no parity, 1 stop bit).

9. What applications is the CH340 module suitable for?
The CH340 module is widely used for:

• STC/STM32/Arduino microcontroller programming and debugging

• Router flashing / brick recovery

• Embedded system serial communication and debugging

• IoT device debugging

• Industrial control and automation serial communication

10. What is the difference between CH340 and other USB-to-serial chips (e.g., PL2303, FT232)?
CH340 is the STC-officially recommended download chip, offering better compatibility and stability compared to PL2303. Key advantages:

• More stable drivers: No download failures due to different driver versions or computers

• Cost-effective: Lower cost than FT232, better performance than PL2303

• Domestic chip: Designed by WCH (Nanjing Qinheng Microelectronics) with comprehensive support

• Broad compatibility: Perfectly compatible with all series MCUs, especially STC microcontrollers