The USB to UART 5V/3V3 adapter is a CH340-based USB-to-TTL serial converter that lets a Windows, Linux or macOS computer talk to microcontrollers and single-board computers over a UART, used for uploading code to Arduino Pro Mini boards, flashing ESP8266 and ESP32 modules, accessing STM32 bootloaders and opening a serial console on a Raspberry Pi.A compact USB-to-TTL serial bridge built on the widely supported CH340 chip. Switch between 5 V and 3.3 V logic to program Arduino Pro Mini boards, flash ESP8266 and ESP32 modules, talk to STM32 bootloaders or open a serial console on a Raspberry Pi. Drivers are built into modern Linux and macOS and are a one-click install on Windows.What can you use it for? Programming Arduino Pro Mini, Pro Micro-style and other boards without a USB port Flashing firmware to ESP8266, ESP-01 and ESP32 modules Serial console access to a Raspberry Pi, router, OpenWrt device or Linux board Debug logging from STM32, PIC, AVR and RISC-V microcontrollers Connecting GPS modules, Bluetooth serial modules and sensors with a UART to a PC Who is it for?Anyone who develops or repairs microcontroller hardware and needs a reliable, driver-friendly serial link that can switch between 5 V and 3.3 V targets.Compatibility Operating systems: Windows (CH340 driver), Linux (built-in ch341 driver), macOS 10.14+ (built-in) Targets: 3.3 V and 5 V microcontrollers; select the level before connecting Tools: Arduino IDE, PlatformIO, esptool, STM32CubeProgrammer, PuTTY, screen, minicom Specifications Chipset WCH CH340 USB-to-serial bridge USB Full-speed USB 2.0 device Logic levels 3.3 V and 5 V selectable I/O Baud rate 2,400 – 115,200 bps Interface Hardware full-duplex UART (TX, RX, VCC, GND) with transceiver buffer Indicators LED activity indicator Power DC 5 V from USB, < 10 mA Operating systems Windows, Linux, macOS (CH340 driver) Weight 4 g What's in the box 2 adapters — flash one board while watching another: 2 × USB to UART 5V/3V3 adapter 5 adapters — workshop or classroom bench: 5 × USB to UART 5V/3V3 adapter 1 adapter — single: 1 × USB to UART 5V/3V3 adapter Shipping and returnsShips from our workshop in Singapore with tracking, charged by parcel weight and shown in full before payment. United States: we do not collect US import duty at checkout. You pay it to US customs or the carrier when the parcel arrives. Tracked SingPost (about 8 business days) $26.99 up to 450 g or $61.99 up to 1.9 kg; DHL Express (3–5 business days) from $123.99. We do not prepay US import duty. Europe, UK & Canada: tracked SingPost Speedpost Saver $10.99 up to 220 g, $18.99 to 450 g, $31.99 to 930 g, $59.99 to 1.9 kg (5–22 business days). Orders over $100 up to 450 g ship free. Import VAT and any duty are paid on delivery. Heavier parcels and assembled robot-arm kits (built and calibrated to order in Singapore, dispatched in 7–10 business days): SingPost Speedpost Priority from $144.99 to Europe, the UK and Canada (9–14 business days), DHL Express from $260.99 to the US. US duty is paid by the recipient on delivery. Everywhere else: the rate for your country is shown at checkout. Full table: shipping, duties and delivery times. 7-day returns; defective items are replaced or refunded with shipping covered.One parcel, one shipping charge: small parts travel together, so the postage on a single 70 g servo is the same as on three of them. A 450 g parcel holds roughly five servos plus horns and cables — which is also about where an order passes $100 and ships free to Europe, the UK and Canada.Frequently asked questionsHow many adapters do I need?One per serial port you want open at the same time. Most bench work needs two: one flashing or programming a board while the other shows a second device's console — an ESP32 talking to an STM32, a Raspberry Pi and the microcontroller it drives, or a GPS module and the board reading it. That is the default pack. A single adapter covers one board; the 5-pack equips a workshop or classroom bench. Two adapters weigh 20 g, five weigh 50 g — all in the same postage band as one.Is the CH340 as good as an FTDI adapter?For everyday programming and serial consoles up to 115200 baud, yes. The CH340 is fully supported by Arduino IDE, esptool and modern operating systems, and it costs a fraction of an FTDI cable.How do I switch between 5 V and 3.3 V?Use the level selector on the board to match your target. Set 3.3 V for ESP8266, ESP32, STM32 and Raspberry Pi; set 5 V for classic 5 V Arduino boards.Can it flash an ESP8266 or ESP32?Yes. Connect TX to the module's RX, RX to TX and GND to GND, hold the module's boot pin low while resetting, then use esptool or the Arduino IDE. Power heavier modules from a separate 3.3 V supply.Do I need to install a driver?Linux and current macOS include the CH340 driver. On Windows install the free CH340/CH341 driver once and the adapter appears as a COM port.What baud rates are supported?2400 to 115200 bps, which covers bootloaders and serial consoles for Arduino, ESP, STM32 and Raspberry Pi.
