I'm wondering if I can power supply the breadboard using 3.3V instead. Are there any side effects, or it is going to work?I think that doing this also the serial connection and outputs will work at 3.3V, is it correct? Can I than connect it to another device with 3.3V serial interface?
Thank you all for your answers.I have read a bit on the internet, and, if I have well understood, I can use the seme circuit of the tutorial just substituting the crystal 16mhz with one at 8 and the circuit should be good. Any other change to the capacitor or other components is needed?Than I should change the bootloader using the one "Arduino Pro or Pro Mini (3.3V 8MHz) with atmega328" and my arduino on the breadboard should work at 3.3v right?