In my PCB project, i have to use only one coin cell battery which they are usually around 3 Volts. Therefore, i decided to use the atmega328p with 3.3 volts by stepping up the 3 volts to 3.3 via voltage regulator.
However, Im not sure if i use 8 Mhz crystal/22pF capacitors and 3.3 volts, will they be enough to make the atmega328p work properly ?
In addition, I have to bootload it but i found some discussions about problems while bootloading the atmega328p 3.3 Volts. Just to solve this problem, is it possible to bootload and upload the codes to atmega 328p by using 16 MHz and 5 volt on a different board. I mean, after uploading the codes to atmega328p, i will remove it from the board which includes 16 Mhz crystal and works under 5 volt and put it to my main PCB which includes 8 MHz crystal and works under 8 MHz? (Im planning to use arduino uno to bootload.)
Lastly, what should be the connections of the pins like AREF, AVCC ? I saw many different schematics. While someone is directly connecting them to VCC, the others adds 0.1 uF capacitor between them and ground. I will use the ADC, then which connections do you advise ?
Thank you so much,