Atmega328p fuses for internal clock, need external crystal?

Using Arduino Microcontrollers
1

I am probably going to buy some TQFP32 Atmega328p chips to try some hand soldering with at some point.

I plan to run them at 8MHz using the internal resonator. Do I need to connect a 16MHz crystal so I can set the fuses, or will I be able to program it without using a crystal? I think I read somewhere that new chips come set to 1MHz so they can be set to what you like but not sure.

2

The ATmega328p are running at the internal 1 MHz oscillator by default, so you don't need an external crystal to set fuses and burn the bootloader.

I suggest you check out MiniCore, which makes it really easy to get started using the internal oscillator. I've also mapped the two pins you save by using the internal oscillator. That means you actually gain two more IO pins (that the Arduino UNO option doesn't give you). There's plenty of information in the README file if you're interested :slight_smile:

3

Excellent, thank you. I made a programming board for some DIL28 Atmega328ps and included a crystal because I thought it was needed for the first programming. Will definitely make it easier if I don't from now on. Thanks :slight_smile: