I've been using the atmega8 for some time and encountered a problem related to timers that require higher clock speeds. I missed the part in the datasheet and thought that the default clock speed of 1MHz is the maximum internal frequency I can get. However, it is quite trivial to fuse the bits and get frequency of 8MHz or even overclock.

What are the drawbacks of using 8MHz clock speed by default?

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    \$\begingroup\$ electronics.stackexchange.com/questions/241575/… \$\endgroup\$
    – G36
    Jun 15, 2017 at 9:49
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    \$\begingroup\$ Because the internal oscillator is very unpredictable, its frequency depends on supply voltage, temperature, aging, phase of the moon etc. You can program the chip to use that internal oscillator by default though. It is more common to use an external crystal to make the clock. Crystals are much, much better at keeping to the same frequency. Then if you program the chip to wait for one minute, it will actually wait for one minute and not 50 or 80 seconds depending on whatever. \$\endgroup\$ Jun 15, 2017 at 9:54
  • \$\begingroup\$ @Bimpelrekkie whooops, it's midnight + full moon now. Should expect minutes to be a bit longer. Thanks. \$\endgroup\$
    – sitilge
    Jun 15, 2017 at 9:57

1 Answer 1


You have higher power consumption. As you say: If you need it, configure it at startup to 8MHz


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