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Author Topic: USB data transfer stuck  (Read 1674 times)


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USB data transfer stuck
« on: December 21, 2020, 09:26:58 AM »

Hi all,
we developed a PCB based on FT4222 chip in order to issue a communication channel between a service PC and a Raspberry PC.
The service PC is connected via USB to our PCB and then the FT4222 bridges out a SPI communication channel to the Raspberry PC.
We are using drivers LibFT4222.dll (version and ftd2xx.dll (version 3.2.14..0).

So far, all is working fine and we had no particular difficulty; but now we are facing some problems while trying to download a significant amount of data (approximatively 5 MB).
Here is what happens:
-   Using a desktop PC all works fine (data transfer is complete in about 2 minutes)
-   Using a Dell laptop (Windows 10 OS)
o   on the LEFT USB port, all works fine
o   on the RIGHT USB port, the communication freezes after 10-15 seconds
o   on the RIGHT USB port, using a USB hub, all works fine
o   on the RIGHT USB port, using a USB hub, all works fine
One more important detail: when the communication is in the freeze state, it restarts immediately when we connect a USB memory per on another port.
Any idea for this kind of issue?

FTDI Community

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Re: USB data transfer stuck
« Reply #1 on: December 22, 2020, 04:31:39 PM »


It's difficult to figure out exactly what could cause your problem with the description of your hardware configuration.

Why are there two USB ports?

There should only be one USB port for FT4222H to be connected to the Host PC.

You can use our UMFT4222EV for test, evaluation and reference. Schematics are provided.

Also note the latest version of LibFT4222 is


You could also send an email to your local support contact as this type of issue may not be suited to a forum:

You can use our https://www.ftdichip.com/FTContact.htm

Best Regards,
FTDI Community