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USB UART Win 8.1 | Cypress Semiconductor

USB UART Win 8.1

Summary: 3 Replies, Latest post by Nick_Danger on 28 Apr 2015 06:21 PM PDT
Verified Answers: 1
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Nick_Danger's picture
116 posts

Need to be pointed in the right direction for using the USB UART on Windows 8, which has strict digital signature enforcement.

Getting a prototype ready for a trade show I found that a Windows 8.1 tablet would not accept the unsigned setup .inf file so I came to the Cypress site and ran an installer that put drivers in Program Files (x86). It appears that the configuration of the part in Creator must be changed to be compatible with the .inf file. If this is true, not sure which strings to change. Also noticed there was no reference to usbser.sys in the file. Do I need to use some other driver?

Also, would like to get a digital signature for our product and modify the .inf file to use our corporate USB PID and VID. Should I open a case for this?

Nick_Danger's picture
116 posts

For anyone else who may have to go through the process.

If you use the USBUART device in your design, you must obtain your own vendor ID VID, which you put into the part in the configuation dialog. Also, you must purchase a code signing signature from any of a number of reputable sources.

You must also modify the example inf file and replace the Cypress VID with your ID.

To get the driver to install on Windows 8, 8.1, you have to use the Visual Studio 2013 and download 8.1 version of the WDK to get the executable 'Inf2Cat.exe'. (Remember that in the /driver part of the command, it is only looking for the directory that holds the inf file, not the actual file name).  You run the program specifying the path to your inf file and the operating system versions you want it to work with. You now have an unsigned catalog file.

In your inf file, be sure to reference the catalog file under [Versions] such as: Catalogfile = my_inf. cat

Then use SignTool to apply the the signature to the cat file.

The cat file and the inf will live in the same directory on the target system. The device manager finds the catalog file by way of the inf file.

pvkv's picture
Cypress Employee
82 posts

 Hi Nick,

Thanks for sharing the information. Can you confrim by following the procedure in your last post, it worked for you ?


Thank you,


Nick_Danger's picture
116 posts

Yes, it worked but I still think I need to change my company name in the inf and inside the USBUART configuration. Here are the steps.

1. Obtained Code Signing Certificate from Microsoft approved vendor.

2. Downloaded Visual Studio 2013 Express (free) and the WDK 8.1.

3. To create a catalog file from inf file. The inf file must contain a reference to the catalog file under [Versions], Catalogfile =

From DOS Prompt: Inf2Cat /drv: C:\<path ONLY to directory containing inf file> /os:6_3_X64,6_3_X86 etc,.

4. To certify the catalog file you just created. 

From DOS Prompt: SignTool sign /f C:\<path and file name of digital cert> /p <password you created c:\ < path and file name of catalog file>

5. Put the catalog file and the inf in the same directory of the target system and use Device Manager to install your driver.

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