Counterfeit FTDI USB-Serial Adapter Roundup

As part of the vacuum tube lighting project, I picked up a bunch of USB-Serial adapters, with the intent of simply building them into the lamp base along with a knockoff Arduino Pro Mini, then plugging in a cheap USB wall wart for power. An Arduino Nano might make more sense, but this lets me use the Pro Minis for other projects where power comes from elsewhere.

Anyhow, I deliberately paid a few bucks extra for “genuine” FTDI chips, knowing full well what was about to happen:

Assorted FT232 Converters

Assorted FT232 Converters

The two boards on the bottom have been in my collection forever and seem to be genuine FTDI; the one on the left came from Sparkfun:

FT232RL - genuine

FT232RL – genuine

The top six have counterfeit chips, although you’d be hard-pressed to tell from the laser etching:

FT232RL - fake

FT232RL – fake

In addition to the boards, I picked up the blue square-ish cable adapters for the HP 7475A plotter project and, again, paid extra for “genuine” FTDI chips. The other adapters, based on Prolific PL2303 chips, I’ve had basically forever:

Assorted FT232 Converters - Cabled

Assorted FT232 Converters – Cabled

Those two have chips with different serial numbers: genuine FTDI chips get different serial numbers programmed during production. The counterfeits, well, they’re all pretty much the same.

Display the serial numbers thusly:

Bus 002 Device 024: ID 0403:6001 Future Technology Devices International, Ltd FT232 Serial (UART) IC
... snippage ...
udevadm info --query=all --attribute-walk  --name=/dev/bus/usb/002/024 | grep ser

All the counterfeit FTDI chips report the same serial number: A50285BI. The PL2303 chips don’t report serial numbers.

For my simple needs, they all work fine, but apparently fancier new microcontrollers expect more from their adapters and the counterfeits just can’t live up to their promises.

For a while, FTDI released Windows drivers that bricked counterfeit chips; the Linux drivers were unaffected.


  1. #1 by brianjwp on 2016-09-02 - 07:26

    I purchased 20 PL2303 (that were supposed to be FTDI chips) from eBay. I was going to hook them up to a RPi and use it as sort of a terminal server in our lab at work. Well, the adaptors worked, but every time the RPi reset, they came up in a different order! So, I ordered 20 more, that said they were genuine, and guess what? They weren’t! There was no way to get them to come up in the same order as they all had the same ID. And when I plugged one into my laptop (Win 7) to try to change the serial number, the driver flagged it as counterfeit in that it would not initialize. So, I found a Digi EtherLite 32 for $65 and it works great!

    • #2 by Ed on 2016-09-02 - 09:14

      every time the RPi reset, they came up in a different order!

      I think you can write udev rules to assign the device names based on the physical USB port (and hub, etc) they’re plugged into, which should work almost as well: the KERNELS attribute might have enough information, depending on how many ports you need.

      But, yeah, a networked serial server seems like a really, really good solution…

  2. #3 by celem on 2016-09-04 - 12:03

    I purchased some Arduino Uno R3 boards from aliexpress that come with a micro-usb instead of the old clunky USB Type B. These very nice boards use a chip that is new to me – the CH340G. It is not a FTDI clone, as I understand it, so it gets around the licensing issues. On a Mint Linux system this chip creates a /dev/ttyUSB0|1 just like a FTDI. Windows machines require new drivers. You can read more about the chip here:

    • #4 by Ed on 2016-09-04 - 15:05

      My next order will be a bunch of Nanos and, having verified that “genuine FTDI” means “counterfeit crap”, I’ll specify “genuine CH340G” chips. Looks like $2.20 in lots of 10 these days, a bit less than what I paid for the Pro Minis last year.

      • #5 by Stewart C. Russell (VA3PID) on 2016-09-04 - 16:22

        even these get confusing, as sometimes they’re called the HL-340 too. They use the ch341 linux driver, and identify as being from QinHeng Electronics. They work pretty well. Another cheap/reliable option is the CP2102, which at the price they sell for, absolutely must be counterfeit. My very cheapest TTL serial adapter uses one, as does an outrageously expensive Kenwood HT that I occasionally use for APRS.

        • #6 by Ed on 2016-09-04 - 16:44

          Given their origin, I’m not sure how to distinguish “genuine” from “counterfeit” for those chips, nor what the difference might be. [sigh]

          Thanks for the tip!

  3. #7 by dueviti on 2016-09-30 - 10:52

    For tinkering with FTDI chips settings from Linux that EEPROM manipulation program might come in handy :

    FTDI only publishes windows tools with .NET framework dependencies…

    • #8 by Ed on 2016-09-30 - 13:22

      FTX_prog expects new-ish FTDI X-series chips, not the classic FT232R chips in my known-good USB adapters. The original ft232r_prog handles those just fine, though.

      Neither program can (re)program counterfeit FTDI chips, which (seem to) have non-writeable “EEPROM” storage: the serial number, for example, remains stubbornly fixed. Drat!

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