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Topic: ATmega168  ... Arduino at 20 MHz (Read 673 times) previous topic - next topic

brianbr

I am looking to "Arduino-ize" an ATMEGA168 board with a 20 MHz resonator on  it. I know about the define in the bootloader for CPU frequency. Can anyone give me a headstart on tracking down  the CPU freq stuff in the core? What place(s) need I look?

thanks ... cheers ... BBR.

mellis

#1
Nov 22, 2007, 07:50 am Last Edit: Nov 22, 2007, 07:50 am by mellis Reason: 1
The boards.txt file in the hardware/ sub-directory of the Arduino application directory specifies the CPU speed for each board.  You can always create your own board definition with the CPU set to 20 MHz.  As for the core itself, you'll probably need to change the delayMicroseconds() function.  The rest might work, although the PWM frequency will be different.  You also might need to change the pre-scale on the analog inputs.  

In any case, let us know what changes you have to make to get it working and I can try to incorporate them into the code base.

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