Take a look at this:
http://www.geocities.jp/arduino_diecimila/obaka/project-2/index_en.html
It seems in that link the chip is running on a internal clock of 8 MHz so adding a Crystal or Ceramic Resonator 16MHz may be a good addition.
Take a look at this:
http://www.geocities.jp/arduino_diecimila/obaka/project-2/index_en.html
It seems in that link the chip is running on a internal clock of 8 MHz so adding a Crystal or Ceramic Resonator 16MHz may be a good addition.