I have already written the firmware and the code is stable. The code uses the
millis() function which uses Timer 0. I also have changed the frequency of the PWM output on pins 3, 9, 10, 11, using the clock select bits (bits 2:0 in TCCR1B & TCCR2B). See http://playground.arduino.cc/Main/TimerPWMCheatsheet
I have an ISP 6-pin programming port on the board and this is my only method of uploading code.
I want minimize on components (and avoid EMC issues), so I have been considering removing the external 16MHz crystal and instead using the internal 8MHz oscillator.
- What do I need to change to use the internal oscillator?
I suspect that I need to change the board.txt file, the clock select bits and the fuses to accommodate for the new frequency.
Can I leave the external crystal in place or do I have to remove it?
If I do leave the external crystal in place and set the fuses to use the internal oscillator, will the crystal continue to resonate or does it get powered down somehow?
(I wish to know this for EMC reasons)