Arduino IDE with ATtiny85 error "multiple definition of `__vector_5"

Question

I am having a problem compiling the code for my ATtiny85 circuit.

I am using the timer/counter0 in normal mode so that when it overflows it triggers the TIMER0_OVF_vect ISR. When I have that ISR in my code, it wont compile and gives this error:

wiring.c.o (symbol from plugin): In function `__vector_5':
(.text+0x0): multiple definition of `__vector_5'
sketch\Glove_heater_v1.ino.cpp.o (symbol from plugin):(.text+0x0): first defined here
collect2.exe: error: ld returned 1 exit status
exit status 1
Error compiling for board ATtiny25/45/85.

Maybe I just need to use a different name for the ISR?

My Code:
//Red LED on PB0
//Blue LED on PB1
//Pushbutton PB2
//Battery voltage divider PB3
//Mosfet control PB4
#include <avr/io.h>
#include <stdint.h>
#include <avr/interrupt.h>
volatile uint8_t checkVoltage = 0;
void setup() {
 DDRB = 0b0010011; //set PB0,PB1,PB4 as output, PB2,PB3 as input
 PORTB = 0b00000011; //set PB0,PB1 HIGH so LEDs are off, other pins LOW
 //Setup TC0 for overflow interrupt trigger
 TCCR0B |= 0b00000101; //clk/1024 prescaler
 TIMSK |= 0b00000010; //set TOIE0 enable overflow interrupt
 sei();
}
void loop() { //do nothing in this test code
}
ISR(TIMER0_OVF_vect){ //Timer/counter0 interrupt check voltage
 checkVoltage = 1;
}

Any ideas are appreciated!

• KIIV: Arduino uses it for counting millis

Answer 1

The error message was:

wiring.c.o [...]: multiple definition of `__vector_5'
Glove_heater_v1.ino.cpp.o [...]: first defined here

__vector_5 is TIMER0_OVF_vect. So you have one definition of this ISR in your sketch, and another one in wiring.c. This wiring.c is part of the Arduino core. As KIIV puts it in a comment, it uses TIMER0_OVF_vect for timekeeping (millis(), micros() and delay()).

You have two options for solving this:

• you can use the other timer (Timer 1) in your sketch, and leave Timer 0 for the Arduino core
• since you are not using the Arduino core anyway, you can get rid of it by simply defining main() in your sketch instead of setup() and loop().

• Eric Navarrete: Ah I see, thank you very much for the explanation. The final code uses both timers so, I will avoid using the Arduino core in this case.