For the CM33 of LPC55S6x family, the trust zone module is integrated, the memory space and peripherals are classified as security and non-security space. In order to generate interrupt in non-security mode, the NVIC module including the NVIC_ITNSx register must be initialized in security mode so that interrupt module can generate interrupt in non-security mode.
The example demos that MRT0 module generates interrupt in non-security mode, the NVIC module is initialized at security mode, MRT0 is initialized at non-security mode.
The project is based on MCUXpresso IDE ver11.1 tools, LPC55S69-EVK board and SDK_2.x_LPCXpresso55S69 SDK package version 2.11.1.