Why disconnected USB cable blocks running code ?

[peteraugustin]

Hello, I use LPC11U35 on my board and it is powered by battery. It is developed under mbed.org platform and I have a problem with USBSerial (USB CDC). The board works fine with connected USB cable or without USB cable. The problem is when I disconnect USB cable from running board because then running code is stoped. I do not know where is problem. Is it a problem with mbed library or is it a hardware problem ?

[peteraugustin]

Hello, Thanks for your answer. One more thing, when I turn off my PC by standard shutdown process with connected USB cable then the problem does not Occur and the code continues.

[jeremyzhou]

Hi Peter,

As the Con Verse mentioned, it needs to use a debugger to figure out the root cause of the issue.

Hope this is clear.
Ping

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[converse]

Probably a problem with your code... Some suggestions:

- removing the power causes a dip in power that is detected as a brown-out, and you have a handler

- there is a USB interrupt dfor device removal that is not being handled

- there is a fault being generated

Whatever the problem, you will need to use a debugger to find the cause