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STM32L151 bricked after attempting USB

Question asked by james.matthew on Aug 14, 2014
Latest reply on Aug 14, 2014 by Clive One
I have about 5 different projects using STM32 F series and 2 using STM32L151 on custom board.   I use the ST-link V2 to program and debug them.

I was attempting to get a custom board with USB port working.  I loaded in custom code that setup the clocks and USB with some of the modified virtual com port examples and my own code to toggle the LEDS etc on the board.  After running the code ( initially with the wrong clock speed which I could reset using the BOOT pins to boot into system memory) . 
My board no longer connects via the st-link utility.  St link is fine as talks to other projects fine.  I have had the same thing happen on 2 boards.

Re-powering doesn't fix it. I can't boot into system memory to get out of it.   My code (that flashes LEDS etc still runs if I re-power.

Is there any way the USB bootloader is permanently active?

Any other suggestions as to how to reset the boards to give me control or have I somehow bricked them.