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whzahp
07-13-2008, 01:16 AM
hi...
If we want to use a frequency for the clock instead of the default 1MHz, we usually connect an external crystal(say 8MHz) to the micro...but we need to set the fuse bits correctly for the external crystal to be recognized. While doing so, many begineers set incorrect fuse bits..& sometimes the serial/parallel programmers refuse to recognize the micro,the next time.

My question is if we set the fuse bit settings to use the internal 4 or 8 Mhz rc oscillator correctly, will there be any difference had we connected an external crystal of the same frequency?...I think the advantage in using the internal rc osc. would be tht there would be less chances of the micro becoming inoperable.....

maddy_nish
07-14-2008, 06:34 PM
Hi whzahp!!!


Its always safe to use the fuse bit settings to change the clk source to external crystal provided you have left the lock bit settings untouched!!
:wink:


Otherwise using fuse bits after refering the data sheets as per need would create no problem..

docel
07-14-2008, 11:05 PM
Careful now, with the Fuse bits!!
ATMEL has an unnecessarily complicated system!!

Check this:
http://elecrom.wordpress.com/2007/10/15/configuring-avr-fuse-bits-for-clock-selection/