Avr fuse setting help!!!

Discussion in 'General Electronics Chat' started by arunskumar05, Jan 19, 2013.

  1. arunskumar05

    Thread Starter New Member

    Nov 1, 2011
    I am beginner in avr programming..
    i am using usbasp programmer and avrdude
    in my program i am using the internal oscillator 8 mhz
    i had calculated the fuse bit using some online fuse bit calculator..and bricked 2 atmega8 mcu..
    what will be the required high and low fuse bit selected for my program..
    please help 8mhz internal osc. for atmega8 using avrdude
  2. vrainom

    Active Member

    Sep 8, 2011
    Take a look at the datasheet in http://www.atmel.com/images/doc2486.pdf pages 216 and 217 and familiarize with it, read through it to understand how to do what you want and why.

    Now here's a short explanation. Note that the bits are active or programed when they're 0 and unactive or unprogrammed when they're 1. So 0 is on and 1 is off.

    Fuse high byte is:
    bit 7: Reset disable, 1 we want this one off as activating it would disable the reset and thus the serial programming.
    bit 6: watch dog timer on, 1 it's off by default.
    bit 5: serial programming enable, 0 we want this one on to use the usbasp serial programmer
    bit 4: clock options, 1 this one has to do with external crystal oscillators which you won't use, so off
    bit 3: eeprom save, 1 by default activate it with a 0 if you want the eeprom data to survive the chip erase command
    bit 2: boot size1, 0 by default
    bit 1: boot size0, 0 by default
    bit 0: boot reset, 1 by default activate it with a 0 if you want to use the boot loader

    So that would be Fuse high byte: b11011001 or 0xd9

    Fuse low byte:
    bit 7: brown out detector level, 1 lower brown out voltage by default
    bit 6: brown out enable, 1 off by default
    bit 5: start up time1, 1 longest by default
    bit 4: start up time0, 0 longest by default
    bit 3-0: clock source, 0100 internal oscillator 8mhz as you want

    so fuse low byte: b11100100 or 0xe4
    Last edited: Jan 20, 2013
    bug13 and arunskumar05 like this.
  3. arunskumar05

    Thread Starter New Member

    Nov 1, 2011
    Thank you that was very helpful post..