USB Serial Adapter

(2 customer reviews)


Out of stock



Plugs into a USB port on your computer and provides you with a hardware serial interface: perfect for giving your home-brew Arduino-compatible projects a USB interface compatible with the Arduino IDE.

Particularly useful when reflashing Sonoff devices, because the output can be switched to 3.3V.

Provides a 6-way female connector with pinout matching the popular FTDI cable. Just plug it into a header intended for an FTDI connection, and you’re good to go.

But this board is so much more than just a USB to serial adapter: it’s actually a really useful general purpose breakout for the ATmega16u2 MCU! We’ve included headers along the edge of the PCB for the rest of the I/O pins, so you can re-flash the board with whatever firmware you like and use it as a general purpose 16u2 development board.


  • Provides virtual serial port on USB connection
  • Micro USB socket
  • 6-pin header matching FTDI cable pinout
  • jumper-selectable 3.3V and 5V operation
  • Breakouts for all ATmega16u2 I/O pins
  • Power, TX, and RX activity LEDs
  • Supplied with Micro USB cable


Additional information

Weight 28 g
Dimensions 140 × 80 × 20 mm

2 reviews for USB Serial Adapter

  1. Ian Exaudi

    Nice looking kit, but does not work with Mac.
    Bought this with the Sonoff Programming Adapter for use with Macbook Pro mid 2018 and a variety of Sonoff boards.
    Doesn’t work with any of the Sonoff boards tried (multiple SV, HT10).
    More worryingly, an email to superhouse support still has not had a response after nearly 2 weeks.

    • Jonathan Oxer

      Hi Ian, if it’s not working with your Mac it sounds like there’s something wrong with the specific board. I use mostly Macs, and the circuit on the adapter is essentially the same as the USB to serial adapter portion of the official Arduino Uno. It even runs the same firmware, so if an official Arduino works on your Mac and the serial adapter doesn’t, there must be something wrong with the adapter. Sorry about not following up your support request. I’ll look that up now.

  2. Norm

    I bought the USB Serial Adapter and the Sonoff Programming Adapter together as I imagine most people would so a review of the pair is appropriate. I had purchased to flash some Sonoff switches to work on Home Assistant.
    The USB Serial adapter is well made. The screen printing is easy to read and there are TX and RX lights that flash making it easy to see when the unit is functioning. I have only used it where 3.3 volt is required, but the switch to allow use of 5.0 or 3.3 volt gives a positive click so it would be difficult to have in the wrong position.
    The “pin header” programming adapter fits snugly into the serial adapter with no play at all and the output pins are set up to match the Sonoff board nicely.
    The two units work well together and it was a simple task to poke the pins through the holes in the Sonoff board and this provided enough contact for the flashing. I did not need to solder pins or headers or use bluetac to stop the pins moving in the holes. The flashing itself went flawlessly on each occasion I used it.
    Very happy with the devices, with the pair being posted about 6 hours after the order was placed.


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