Hi steetven,
The PTB4 pin defaults to the NMI_b function.
Driving the NMI signal low forces a non-maskable interrupt, if the NMI function is selected on the corresponding pin.
It is not recommended to use this pin for other functions.


If you must use this pin, you need to configure SIM_SOPT[NMIE].
![SIM_SOPT[NMIE].png SIM_SOPT[NMIE].png](https://community.nxp.com/t5/image/serverpage/image-id/155851i04E21F451B0DC8E8/image-size/large?v=v2&px=999)
Best Regards,
Robin
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