Arduino Forum

Forum 2005-2010 (read only) => Hardware => Development => Topic started by: tomnd on Jan 18, 2011, 02:11 pm

Title: ATMega1280/2560 at 8Mhz
Post by: tomnd on Jan 18, 2011, 02:11 pm
So I'm looking to use a 1280/2560 chip in a circuit, programmed with Arduino. However, apparently they're as rare as hens' teeth, and I've managed to get hold of some ATMega1280-8AUs, which are set to run at 8Mhz instead of 16.

Now clearly this is going to affect some things, as I've read bits here and there about fiddling with the clock on the ATM128/328, but nothing I could gather together completely.

What will I need to do to make sure that the programs I write will work okay? I need accurate timings as I need the chip to do some servo control....

Title: Re: ATMega1280/2560 at 8Mhz
Post by: intermelt on Jan 21, 2011, 05:00 am
By default they are set to run at 1MHz so you will need to change the fuse settings to remove the divide by 8 on the clock so it will run at 8MHz.  Then it should just be a matter of changing the speed in the boards.txt file located in your Arduino folder.  Probably copy the settings for the Mega1280, rename it to something else and change the clock setting to 8MHz.