USB to 3.3V/5V Serial UART TTL Auto Sensing Adapter

(4 customer reviews)


Windows 10 USB Serial UART TTL Adapter Cable

The USB to serial UART TTL adapter is auto sensing and is supported in Windows 10 or earlier OS and Mac OS and Linux. The serial UART adapter electronics automatically sense the voltage for its operation. Transmit and receive LED lights are embedded into the translucent USB molded jacket.


  • Perfect for embedded systems requiring an a serial connection
  • USB protocol handled through the FTDI Chip
  • Auto sensing voltage electronics
  • Data transfer rates from 300 baud to 3 Mbaud at TTL levels

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The SS-TTL5P USB to TTL 3.3V/5V Auto Sensing Adapter is a USB to Serial UART (TTL Auto level) adapter. It allows you to connect your computer through an available USB port and uses it as a regular serial communication. All USB protocol is handled within this adapter. There is no other device or programming required and supports plug-and-play technology.

USB to 3.3V/5V Serial UART TTL Auto Sensing Adapter GM-TTL5P


The adapter is perfect for embedded systems that require a serial connection to a computer and is compliant with USB spec. 2.0 &1.1. The board attaches directly to the USB bus via a standard type “A” receptacle connector for upstream data. The USB to Serial UART shows up on any Windows computer as a standard serial COM port. Any applications that talk to this COM port are automatically converted to USB and back to UART to your target board.

Additional Features:

  • The Cable provides a USB to TTL Auto Sensing Serial interface with various end connectors.
  • Single board USB to asynchronous serial data transfer interface
  • Entire USB protocol handled by the electronics in the cable USB
  • UART interface support for 7 or 8 data bits, 1 or 2 stop bits and odd / even / mark / space / no parity
  • Data transfer rates from 300 baud to 3 Mbaud at TTL levels.
  • Auto Voltage sensing
  • Transmit and receive LEDs
  • UHCI / OHCI / EHCI host controller compatible
  • Low USB bandwidth consumption.


5-Pin Header Pin Assignment
Pin 1 VCC
Pin 2 TXD
Pin 3 RXD
Pin 4
Pin 4 GND

OS Support:

  • Windows 7, 8, & Windows 10
  • Mac OS-X
  • Linux

Packages Contents:

  • USB to 3.3V/5V TTL Auto sensing adapter
  • Latest FTDI Driver (also available for download)
  • SS-TTL5P Product Manual (available for download)

Additional information

Weight .33 lbs
Dimensions 3 × 3 × .75 in




Cable Length

Supported OS

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USB to 3.3V/5V TTL


1 year from date of purchase.

Drivers & Manuals

4 reviews for USB to 3.3V/5V Serial UART TTL Auto Sensing Adapter

  1. Mark

    Works great, BUT here’s the key piece of information you need to know, which isn’t mentioned in any specs or documentation: the cable doesn’t “magically” sense the correct voltage level. Unlike the cables dedicated to 3.3v or 5v, on this cable the Vcc pin is an INPUT. You have to connect your device’s Vcc to this cable to provide a reference voltage and current source for the output drivers. If you just hook up Tx, Rx and GND, it won’t work in many cases. Easy to do — if you know. Second thing: FTDI offers a great little utility that lets you reprogram the EEPROM — you can invert the outputs, remap them, etc. Super-useful.

  2. W. Lear

    The USB to serial adapter uses the ubiquitous FTDI chip and functions flawlessly. My only complaint was it came with absolutely no documentation whatsoever. I needed to replace the connector. After some searching I I found the Gearmo website which contained a small image showing the pinout. It would have been nice for the cable to include a sheet with the pinout, specs, and link to the FTDI site to get the driver.

  3. John L. Sloan “Chip Overclock”

    I clipped off the Molex-style connecter from the end, stripped the wires, soldered some jumper wires onto them, made it look nice with a little shrink wrap, and put some tiny logic clips on the ends of the jumpers. Now I have a device that allows me to “spy” on a logic-level serial port of the microprocessors and microcontrollers that I make use of in my work as a embedded product developer. Of course, you can use it as is if you put the right sized pin header down on your board. But existing boards are seldom that accommodating. This little gadget now has a permanent place in my tool bag. Because it is based on an FTDI USB-to-serial converter chip, it works flawlessly with tools ranging from PuTTY on my Windows laptop to Terminal on my Mac. No tiny little circuit board to keep track of, just a cable with a USB connector on one end and logic clips on the other. The time it took me to modify it was well worth it.

  4. hmcvey

    Works great we use it for 3.3 V. I used to make a converter box utilizing a RS232max, no more this is smaller and available, works great, set up with a comm port and windows 7

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