Can't turn off bootloader

[jeffsylvester]

Someone probably instantly knows the answer to this,  I have FRDM-K66F and I pushed the reset button.  now the board is stuck in Bootloader mode, and it appears as USB mass storage device.   How Do I undo or cancel bootloader mode so I can get back to debug mode using USB to serial Com port?

Thanks

[mjbcswitzerland]

Jeff

Unfortunately you have lost the code and you will need to reprogram the loader/debugger/VCOM again.

You can get the images (Segger or P&E versions recommended) from OpenSDA Serial and Debug Adapter|NXP 

Presumably you are using Win 8.1 or Win 10 or MAC, with which the boot loader is not compatible with and you will destroy the loader if you connect with the button pressed and you will need a Win 7 PC to load the code with (there are methods to disable the behavior in Win 10 etc. which causes the problem but it is a bit tricky (messing in the registry)). If you search the forum or maybe check out some of Erich Styger's blog entries you may find instructions. I did write a guide in the forum a few years ago  but it is difficult to find again (I keep a Win 7 laptop with me to recover when it happens to avoid the hassle).

There is some background on the reasons for the difficulties that started in about 2014 with Win 8.1 release and MAC OS here:
http://www.utasker.com/kinetis/USB-MSD-MAC.html

Regards

Mark