ATMEGA328 breadboard clock change

I would like to modify the "ATMEGA328 on a breadboard" configuration to run with a 4MHz crystal and not an 8MHz. I have not been able to find the file to change in any of the "boards.txt" files.

Is there somewhere else to look?

Thanks

Why not just change 16000000L to 4000000L in the Uno entry? Copy the section & give it a new name if you want.

##############################################################

uno.name=Arduino Uno
uno.upload.protocol=arduino
uno.upload.maximum_size=32256
uno.upload.speed=115200
uno.bootloader.low_fuses=0xff
uno.bootloader.high_fuses=0xde
uno.bootloader.extended_fuses=0x05
uno.bootloader.path=optiboot
uno.bootloader.file=optiboot_atmega328.hex
uno.bootloader.unlock_bits=0x3F
uno.bootloader.lock_bits=0x0F
uno.build.mcu=atmega328p
uno.build.f_cpu=16000000L
uno.build.core=arduino
uno.build.variant=standard

After doing that, would I have to run "make" to get all the files up to date?

CrossRoads: Why not just change 16000000L to 4000000L in the Uno entry? Copy the section & give it a new name if you want.

##############################################################

uno.name=Arduino Uno uno.upload.protocol=arduino uno.upload.maximum_size=32256 uno.upload.speed=115200 uno.bootloader.low_fuses=0xff uno.bootloader.high_fuses=0xde uno.bootloader.extended_fuses=0x05 uno.bootloader.path=optiboot uno.bootloader.file=optiboot_atmega328.hex uno.bootloader.unlock_bits=0x3F uno.bootloader.lock_bits=0x0F uno.build.mcu=atmega328p uno.build.f_cpu=16000000L uno.build.core=arduino uno.build.variant=standard

Here is a good tutorial for what you want:

http://ava.upuaut.net/?p=383

I don''t think you need to run Make or anything. Just restart the IDE, select the new board type (assuming you copied the section & edited each line to replace "uno." with something like "uno4M." ) Tools:Board:uno4M, and proceed normally.