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AN13750 is available under the S32G2 product page (link: S32G2 Safe and Secure Vehicle Network Processor | NXP Semiconductors), this Application Note provides some general guidelines on how to use the NXP provided bootloader. You could follow the M7 steps to load your application.
As a note, instead of the FreeRTOS example, we recommend using a simpler application (like a blink example) for it to be as simple as possible, then continue adding simple applications to multiple cores until the idea on how to use it is clear enough, mainly the configuration. After this, you can start adding more complex applications to ensure the correct functionality.
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