i program my atmega with USBasp ,and i set the fuse bits hfuse:0xC9 and lfuse :0xff. when i upload my simple code

int main(void)
       DDRB |= 1<< PINB1 ;

       PORTB|= 1<<PINB1;
       while (1) 


the MCU keeps resetting(led keeps blinking), i tried using usbasp as power supply and also i tried using 9v volt battery with regulator but still the same problem ( and i have 0.1uf capacitor between vcc and ground and pullup resistor in the reset pin). i also bought a new atemga328p ( i thaught the other is dead) but always the same problem.

  • 7
    \$\begingroup\$ Is the watchdog (de-)activated? \$\endgroup\$
    – Janka
    Jan 22, 2018 at 10:52
  • \$\begingroup\$ thanks man , i changed hfuse to 0xD9 then reset it and it worked fine \$\endgroup\$
    – Mourad
    Jan 22, 2018 at 11:20
  • \$\begingroup\$ @Janka your comment was spot-on. Perhaps you could post an answer so that OP can choose whether to accept it \$\endgroup\$
    – clabacchio
    Jan 22, 2018 at 15:09
  • \$\begingroup\$ It was a lucky guess … nothing more. \$\endgroup\$
    – Janka
    Jan 22, 2018 at 15:31

1 Answer 1


Solution is set to set hfuse to hfuse:0xD9 instead of 0xC9 , to unprogram the watchdog

  • \$\begingroup\$ You can mark your own answer as accepted. \$\endgroup\$ Feb 4, 2018 at 11:16

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