ATmega328 + crystal + arduino program

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

Hi,

If i use a ATmega328 and a crystal 8MHz and i run this at 3.3V, in the arduino program i can use this option Arduino Pro or Pro Mini(3.3V, 8MHz) w/ ATmega328?
And all work same of arduino card for the arduino code?
I can programming my ATmega328 with my arduino program (Arduino 0018)?

If i use a ATmega328 and a crystal 12MHz and i run this at 3.3V, what i must to do for the arduino program work with my ATmega?

All options:

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I must change the source code for arduino program for all work with 8MHz or 12MHz?
I must change the bootloader?

Thanks you

2

Let me take a shot at this. I don't think you need to change anything as far as the bootloader goes since you are dealing with the same MCU (ATMega328P).

But if you change the crystal frequency, you will have to take into consideration the effects on timing since the Arduino timing methods assume that the MCU runs at a particular frequency (i.e. 8MHz or 16MHz). Also, if you are using clocks higher than 8MHz you might want to increase the supply voltage to 5V instead of 3.3V.

3

thank AlphaZeta you for your reply! :slight_smile:

My plan picture is on this French post:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1266901277/30#30

On my plan i put a crystal 16MHz (is my error) but on 3.3V the higher frequency is 12MHz.

Then if i put a crystal 8MHz i must programming my ATmega with this option Arduino Pro or Pro Mini(3.3V, 8MHz) w/ ATmega328?

And if i use a NB1A Microcontroller Board (ATmega328P + 12MHz) what option i must chose for programming the ATmega?
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Thanks you