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How to set USB serial number attribute of virtual com port (stm32f4)

Question asked by achterop.sietse on Sep 5, 2017
Latest reply on Sep 19, 2017 by achterop.sietse

Hello,

I am working with stm32f4 discovery and linux systems.

We have a larger number of discovery boards that are interfaced via USB, and want to be able to connect to each one uniquely. I normally do that by using the attribute "serial" that USB can give me, and I use the number in an udev-rule to get a unique devicename in /dev. An example of such a rule is:

 

SUBSYSTEM=="tty", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="5740", ATTRS{serial}=="00000000001A", SYMLINK+="VHP100"

 

The problem is that this serial number is NOT fixed. It sometimes changes after a reboot.  I have never seen this with other devices.

The question is, how can I fix/set this number? A cannot find anything in the CubeMX stuff about this.

 

UPDATE: The fact that the number changes suggests that it resides in software. Does anyone know where the value is set?

 

Thanks in advance,

      Sietse

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