MKL26 no interrupts

[panayot]

Hi All,

I have a strange problem. We had a first batch of MKL26Z64 based boards build, tested our software on it and eventually everything worked fine. Of course we found a couple of problems, which were mainly in other modules not in the MCU. We corrected them and made a second batch of those boards and this is where problems came in. The same software runs fine on the first batch of boards, but when we put it on the latest batch it starts but no interrupts routines are being called, not even the SysTick. Needless to say that without interrupts the device is useless. MCU's are 100% the same on both boards, the boards themselves are 90% the same but the behavior is totally different. We tried everything we coulld think of, including making modifications to the new board to be 100% as the old one. We tried to run simple examples on the new board, but if they use interrupts nothing happens. If you put an endless loop, to blink an LED for example, it works so the MCU is alive and kicking but interrupt routines are not being called.

Does anybody have an idea what might be the problem?

Thanks in advance.

Best regards,

Panayot

[Jorge_Gonzalez · Accepted solution]

Hello Panayot Daskalov:

Your issue sounds similar to the one reported in the thread from the next link:

Fresh MCUs refuses interrupts

Did you modify anything in the new boards that would affect NMI_b pin voltage state during power-on?

To discard this you can try disabling NMI functionality by writting to Flash Configuration Field. For an example using CodeWarrior or KDS check the next discussion:

:smileyalert: The discussion is for a Kinetis K part. The Flash Configuration Field and specifically the FOPT byte will be different for KL26. Refer to the chapter called "FOPT boot options" for details about each bit.

Re: How to modify FTFL_FOPT register on Kinetis K10 to change boot options?

Regards!,
Jorge Gonzalez

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[panayot]

Dear Jorge,

Thanks for the reply. Yes, that was exactly the problem - we use PTA4 / NMI_b to control a Enable signal for external chip. In the new batch of boards we have placed a pull-down resistor there. This was obviously causing problems, because when we removed it everything worked fine.

Thanks for your help!

Best regards,

Panayot