Product Overview
The CP2102 USB to TTL UART Serial Converter Module (Red Version) is a complete, ready-to-use programming and communication solution designed to bridge the gap between a computer’s USB port and a microcontroller’s serial interface. Based on the high-performance Silicon Labs CP2102 bridge controller, this module creates a virtual COM port on your computer, allowing you to program, debug, and communicate with embedded systems that lack native USB connectivity.
What sets this kit apart is its complete package – the module comes pre-soldered with header pins and includes a high-quality USB cable and packaged packaging, making it a particularly convenient choice for users who want a hassle-free, “out of the box” experience without needing to source cables separately. The red PCB version offers clearly labeled 5V, 3.3V, TXD, RXD, DTR, and GND pins, and the kit often includes jumper wires for immediate prototyping.
This module is specifically designed to be an STC Microcontroller Programmer Downloader, making it widely used for flashing code onto STC series microcontrollers as well as a universal serial adapter for Arduino Pro Mini, ESP8266, ESP32, STM32, and other UART devices. With support for baud rates up to 1.5 Mbps and broad driver compatibility across Windows, macOS, and Linux, this CP2102-based converter is a trusted choice for electronics hobbyists, educators, and professionals.
Key Features
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Genuine CP2102 Chipset: Based on the high-performance Silicon Labs CP2102 USB 2.0 to UART bridge controller, known for excellent stability and broad compatibility
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Complete Kit with Cable & Accessories: Includes the red module, USB-A to USB cable, and often jumper wires – ready to use right out of the box
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6-Pin Interface with Auto-Reset: Standard 6-pin 2.54mm pitch pinout (3V3, 5V, TXD, RXD, DTR, GND) featuring DTR line for automatic reset of Arduino-compatible boards during upload
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Dual Voltage Output: Provides both 3.3V (up to 50-100mA) and 5V (up to 500mA) power outputs to supply your target device
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STC Microcontroller Programmer: Specifically designed to support full range of STC single-chip microcomputers for program download and flashing
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High-Speed Communication: Supports baud rates from 300 bps up to 1.5 Mbps, suitable for fast data transmission and programming
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Integrated Self-Recovery Fuse: Onboard resettable fuse protects your computer’s USB port and the module from short circuits and overcurrent conditions
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Visual Status LEDs: Three onboard LEDs provide clear status indication: POWER (red), TXD (green), and RXD (blue) for real-time activity monitoring
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Compact Form Factor: Small PCB footprint (approx. 45mm × 14mm) allows easy integration into projects and enclosures
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Cross-Platform Driver Support: Works with official Silicon Labs VCP drivers on Windows, macOS, and Linux
Technical Specifications
Pinout & Interface Guide
The board features a 6-pin header (2.54mm pitch) with clearly labeled silkscreen markings:
Important Connection Note: TXD and RXD are labeled from the CP2102’s perspective:
LED Indicators
Usage Guide
Wiring Instructions
IMPORTANT: Always connect the ground (GND) between the CP2102 module and your target device first. Redo the connection check if communication fails.
Standard Programming Connection (e.g., for Arduino Pro Mini, STC Microcontroller)
Self-Test / Loopback Test
To verify the module is functioning correctly, short the TXD and RXD pins together with a jumper wire. What you send will be received back, confirming the module is working.
Software Setup
1. Install Drivers
The CP2102 requires Virtual COM Port (VCP) drivers:
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Windows: Download the “CP210x Universal Windows Driver” from the Silicon Labs website. The driver may install automatically on Windows 10/11
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macOS: Drivers are usually included; restart your computer if the device is not recognized
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Linux: Drivers are built into the kernel (cdc-acm). The device will appear as /dev/ttyUSB0 or /dev/ttyACM0
Driver Installation Tips for Windows 8/8.1:
If you encounter a “Data Invalid” error during driver installation on Windows 8/8.1:
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Press Win + R and enter services.msc
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Locate “Device Install Service” and “Device Setup Manager” in the services list
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Ensure both services are started (click “Start” if not running)
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Re-attempt driver installation
2. Identify the COM Port
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Windows: Open Device Manager. Look for “Silicon Labs CP210x USB to UART Bridge” under Ports (COM & LPT). Note the COM port number
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macOS/Linux: Open a terminal and type ls /dev/tty.*. Look for a device named tty.SLAB_USBtoUART or ttyUSB0
3. Verify Communication
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Open a serial terminal program (e.g., PuTTY, Arduino Serial Monitor, CoolTerm)
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Select the COM port and set the baud rate (e.g., 115200)
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Perform a loopback test (short TXD to RXD) and type characters to verify echo
Application Examples
1. STC Microcontroller Programming
The module is specifically designed for STC series microcontroller program download. Connect TXD→RXD, RXD→TXD, GND→GND, and power the target device appropriately. Use the STC-ISP programming software to flash firmware.
2. Programming an Arduino Pro Mini
Connect the module as shown in the wiring diagram. In the Arduino IDE, select the correct COM port and board (“Arduino Pro or Pro Mini”), then click Upload. The RTS/DTR line will handle the reset automatically.
3. Debugging ESP8266 / ESP32
For these 3.3V logic boards, use the 3V3 pin for power. Connect TX→RX, RX→TX, and GND→GND. Use serial monitor to view debug output at 74880 baud (ESP8266 bootloader) or 115200 baud.
Q: Is the CP2102 better than CH340?
The CP2102 is generally considered to have superior stability and more reliable drivers than the CH340, especially on macOS and for high-speed communication. It also supports higher baud rates up to 1.5 Mbps
Q: What microcontrollers can I program with this module?
This module is widely used for STC series microcontrollers, Arduino Pro Mini, ESP8266, ESP32, STM32 (“Blue Pill”), and any other UART-programmable device with 3.3V or 5V logic.
Q: What does the DTR/RTS pin do?
The DTR (Data Terminal Ready) or RTS (Request to Send) pin is used to automatically reset Arduino-compatible boards when uploading a new sketch. It pulls the reset line low, triggering the bootloader.
Q: Do I need an external power supply?
For low-power microcontrollers like Arduino Pro Mini (no USB), the module’s 5V output can provide sufficient power. For higher current devices (motors, displays, etc.), use an external power supply.
Q: My computer doesn't recognize the device. What should I do?
Follow this checklist:
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Driver issue: Download the latest CP210x drivers from Silicon Labs website
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USB Cable: Ensure you are using a data cable, not a charge-only cable
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Check Device Manager: Look for any unrecognized devices with a yellow warning icon
Q: What is the "Data Invalid" error on Windows 8/8.1?
This occurs when the “Device Install Service” and “Device Setup Manager” services are disabled. Open services.msc and start both services, then retry driver installation.
Q: Why is the LED blinking instead of solid?
The red POWER LED should be solid. The TXD and RXD LEDs blink only during data communication. At higher baud rates, the LEDs may appear dimmer or blink very rapidly
Q: Why can't I upload code to my board?
Common issues:
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Wiring mismatch: Double-check that TXD → RX and RXD → TX are correctly connected
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Power issues: Ensure the target board is properly powered
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Wrong COM port: Verify the correct port is selected in your IDE
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Auto-reset not working: For manual reset, press reset button immediately after upload starts
Q: What can I build with this CP2102 module?
Popular applications include:
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STC Microcontroller Programming: Download firmware to STC series chips
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Arduino Pro Mini Programming: Upload sketches without USB port
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ESP8266/ESP32 Debugging: View serial debug output
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GPS Module Interface: Connect GPS modules to computers
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General Serial Communication: Any UART device to PC communication
Q: Can this module power my microcontroller project?
The 5V output is derived directly from the USB port and limited to about 500mA (USB 2.0 standard). The 3.3V output is limited to about 50-100mA. Suitable for low-power microcontrollers (Arduino Pro Mini, ESP32 without active Wi-Fi).
Q: How do I perform a self-test to verify the module is working?
Perform a loopback test by shorting the TXD and RXD pins with a jumper wire. Open a serial terminal and type characters – they should echo back, confirming the module is functioning correctly.
