Persistent Variable Setup

Persistent Variables are variables that should not be cleared by the runtime startup code such as during a reset. If you have a variable which you don't want to have initialized upon a Power On Reset (POR), Watch Dog Timer Reset (WDT), or Master Clear Reset (MCLR), define it as Persistent. This is often needed for bootloader entry / exit, when the application needs to differentiate between a WDT, MCLR, or other reset condition. An example of how to establish a Persistent Variable is provided below:

/*******************************************************************************
 *   Persistent RAM variables, which are not initialized at power up / reset.
 *
 ******************************************************************************/

#if defined(__XC8__)
    #ifdef __CCI__
        __persistent unsigned char PORStatus;
    #else
        persistent unsigned char PORStatus;
    #endif

#elif defined(__XC16__)
    #ifdef __CCI__
        __persistent int PORStatus;
    #else
        int PORStatus __attribute__((persistent));
    #endif

#elif defined(__XC32__)
    #ifdef __CCI__
        __persistent int PORStatus;
    #else
        int PORStatus __attribute__((persistent));
    #endif

#endif
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