8 years ago.

FRDM K64F: Cannot enter in bootloader

Hello everyone!

So, I've recently been using my FRDM K64F board for a university project and we had to use a different firmware from the mbed one. The firmware is JLink_OpenSDA or something similar that we used to have the J segger debug mode.

Now the project is over and I'm trying to get back to the mbed interface firmware, so I unplug the board from the PC, hold the reset button and plug back the USB cable till the green LED starts blinking slowly. Now the bootloader should appear, but this is not happening.

Do you have any idea why? What can I do to fix the problem?

Thanks in advance for your help!

1 Answer

8 years ago.

What does appear? The JLink one as if you didn't press anything?

I happened to have this problem yesterday also, for me I had populated J25 (not a clue why, maybe it was by default?), make sure it is in the correct setting with a jumper (eg: If it doesn't work now, try the other option).

Nothing appears. The firmware installed is for the Micrium OS, so I can only use the board via Kinetis. But that's really low-level programming and I don't really want to spend too much time with that.

I wanted to go back to the mbed firmware and apparently it is impossible.

I've made some reasearch on the web and the most common answer is that the bootloader of the board tends to be easily corrupted. This means that the only possible solution is to copy the non-corrupted bootloader from another board which requires using a communication device and being able to program it.

In few words... I'll probably have to buy another board (sigh)

posted by Nicolò Bagarin 08 Dec 2016

So J25 is in the correct setting? Quite frankly it shouldn't be easy to really corrupt the bootloader without also removing the regular functionality.

posted by Erik - 08 Dec 2016