I want to run an atmega328p board at 3.3v. By reading the datasheet of this chip, it can run up to 8MHz at that voltage. And I would like to have a stable oscillator, such as CSTCE8M00G15C99-R0 SMD3213-3P, which is a 8M 0.1% 33pF one. The problem is the original oscillator of a nano I found/believe is a 16M 15pF one. Will the 33pF here cause any issue?
When you replace a crystal, you may also need to replace the load capacitors.
To get the values for those capacitors, the stray board capacitance (typically in the range of 4 -10 pF) should be taken into account.
On the other hand, many people have reported successfully running an ATmega328 at 3.3V with a 16 MHz crystal.
Note that you can run atmega328 at 8MHz without oscillator at all, using internal clock
Check out the MiniCore core. That core makes it easy to choose many bootloader options including processor (328, 168, 88, 48, 8), clock frequency, clock source, BOD, ...
What is that clock source?
Atmega328 datasheet section 13.6:
Calibrated Internal RC Oscillator
By default, the Internal RC Oscillator provides an 8.0MHz clock. Though voltage and temperature dependent, this clock can be very accurately calibrated by the user. This clock may be selected as the system clock by programming the CKSEL
You can also configure a clock pre-scaler to divide the existing 16MHz clock by two, giving you 8MHz. But that wouldn't apply to when the bootloader is running, which could be a problem.
(Most people report that under "typical" environmental extremes, the 328p runs fine at 16MHz, even with 3.3V power.)
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