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NMI_B not beeing inserted on KL03Z

Question asked by Tomaz Lovrencic on Jul 16, 2019
Latest reply on Aug 21, 2019 by Mark Butcher

I have Kinetis MKL03Z8VFG4 on custom board and trying to setup NMI interrupt handler to handle logic 0 during the boot (i.e. external device is connected to pin PTB5/IRQ_12/NMI_b  and pulling to GND). I have setup MWE from SDK 2.x example where FOPT register is beeing set:

__attribute__ ((used,section(".FlashConfig"))) const struct {
   unsigned int word1;
   unsigned int word2;
   unsigned int word3;
   unsigned int word4;
} Flash_Config = {0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFF3FFE};

Looking into datasheet my configuration sets:

  • BOOTSRC_SEL = 00 (Boot from FLASH),
  • FAST_INIT = 1 (Fast Initialization),
  • RESET_PIN_CFG = 1 (RESET_b pin is dedicated),
  • NMI_DIS = 1 (NMI_b pin/interrupts reset default to enabled),
  • BOOTPIN_OPT = 1 ( Boot source configured by FOPT[7:6] ( BOOTSRC_SEL) bits),
  • LPBOOT = 11 (Core and system clock divider (OUTDIV1) is 0x0).


Then I override default WEAK IRQ handler by defining:

void NMI_Handler(void)


   // TODO: handle NMI_b pin state

..but PC never goes into this function.

Why is NMI_Handler(void) not beeing called, I am missing something?