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edited Jun 4, 2015 at 23:52

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With a real vector you'd get the more meaningful:

extern "C" void _VECTOR(7) (void) __attribute__ ((signal,__INTR_ATTRS));
void _VECTOR(7) (void) {
    // something here
}

Of course, _VECTOR() itself is a macro:

lib/avr/include/avr/sfr_defs.h:#define _VECTOR(N) _vector ## N

So that further expands out to:

extern "C" void __vector_7 (void) __attribute__ ((signal,__INTR_ATTRS));
void __vector_7 (void) {
    // something here
}

And magically, that new function name of __vector_7 is directly referenced from the standard vector handling code in the startup library crt of the AVR compiler.

With a real vector you'd get the more meaningful:

extern "C" void _VECTOR(7) (void) __attribute__ ((signal,__INTR_ATTRS));
void _VECTOR(7) (void) {
    // something here
}

Of course, _VECTOR() itself is a macro:

lib/avr/include/avr/sfr_defs.h:#define _VECTOR(N) _vector ## N

So that further expands out to:

extern "C" void __vector_7 (void) __attribute__ ((signal,__INTR_ATTRS));
void __vector_7 (void) {
    // something here
}

And magically, that new function name of __vector_7 is directly referenced from the standard vector handling code in the startup library crt of the AVR compiler.

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answered Jun 4, 2015 at 23:48

Majenko

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The vector names are all defined within the header files for the main chip in the compiler. The IDE doesn't need to know anything about that kind of thing - that's all up to the compiler.

Look for the files "lib/avr/include/avr/io*.h within the compiler in your chosen IDE. In there are all the chips and all their definitions.

For instance, the ATMega328P definition (iom328p.h) has this list:

#define INT0_vect         _VECTOR(1)   /* External Interrupt Request 0 */
#define INT1_vect         _VECTOR(2)   /* External Interrupt Request 1 */
#define PCINT0_vect       _VECTOR(3)   /* Pin Change Interrupt Request 0 */
#define PCINT1_vect       _VECTOR(4)   /* Pin Change Interrupt Request 0 */
#define PCINT2_vect       _VECTOR(5)   /* Pin Change Interrupt Request 1 */
#define WDT_vect          _VECTOR(6)   /* Watchdog Time-out Interrupt */
#define TIMER2_COMPA_vect _VECTOR(7)   /* Timer/Counter2 Compare Match A */
#define TIMER2_COMPB_vect _VECTOR(8)   /* Timer/Counter2 Compare Match A */
#define TIMER2_OVF_vect   _VECTOR(9)   /* Timer/Counter2 Overflow */
#define TIMER1_CAPT_vect  _VECTOR(10)  /* Timer/Counter1 Capture Event */
#define TIMER1_COMPA_vect _VECTOR(11)  /* Timer/Counter1 Compare Match A */
#define TIMER1_COMPB_vect _VECTOR(12)  /* Timer/Counter1 Compare Match B */
#define TIMER1_OVF_vect   _VECTOR(13)  /* Timer/Counter1 Overflow */
#define TIMER0_COMPA_vect _VECTOR(14)  /* TimerCounter0 Compare Match A */
#define TIMER0_COMPB_vect _VECTOR(15)  /* TimerCounter0 Compare Match B */
#define TIMER0_OVF_vect   _VECTOR(16)  /* Timer/Couner0 Overflow */
#define SPI_STC_vect      _VECTOR(17)  /* SPI Serial Transfer Complete */
#define USART_RX_vect     _VECTOR(18)  /* USART Rx Complete */
#define USART_UDRE_vect   _VECTOR(19)  /* USART, Data Register Empty */
#define USART_TX_vect     _VECTOR(20)  /* USART Tx Complete */
#define ADC_vect          _VECTOR(21)  /* ADC Conversion Complete */
#define EE_READY_vect     _VECTOR(22)  /* EEPROM Ready */
#define ANALOG_COMP_vect  _VECTOR(23)  /* Analog Comparator */
#define TWI_vect          _VECTOR(24)  /* Two-wire Serial Interface */
#define SPM_READY_vect    _VECTOR(25)  /* Store Program Memory Read */

Further, _ISR() is just a macro. It creates a suitable function prototype for your function, and if that happens to include a valid vector then it becomes an ISR.

#  define ISR(vector, ...)            \
    extern "C" void vector (void) __attribute__ ((signal,__INTR_ATTRS)) __VA_ARGS__; \
    void vector (void)

That is defined in "avr/interrupt.h" in the compiler's include files. With your gibberish you'd end up with:

extern "C" void GibERisH (void) __attribute__ ((signal,__INTR_ATTRS));
void GibERisH (void) {
    // something here
}