You can check the UNO's schematic. You can use this as a starting position. You can leave out the things you don't need. You might for example have no need for a voltage regulator on your board.
You may also have a look at the schematic of the Pro Mini, which are a lot more bare-bones.
Yes it's possible. To use the ATmega328P to "emulate" an Arduino Uno board (without the USB part) you just need 3 ou 4 additional components: the oscillator, two capacitors and a resistor. Please take a look at: https://www.arduino.cc/en/Tutorial/BuiltInExamples/ArduinoToBreadboard for a schematic/breadboard.
The Atmega328P features itself the ...
You can use the clock prescaler in conjunction with the CKDIV8 fuse to operate with an 8MHz clock but using a 16MHz crystal.
See the "CLKPR – Clock Prescale Register" details in the data sheet for details (Page 36 in my data sheet 07/2012).
Basically you set the CKDIV8 fuse so the processor runs at 2MHz after power-up. Then once up and running you ...
Hello The 328 "PB" has major issues with running external clocks...(yes I have first hand experience with this PB model)... Try switching to the internal oscillator as I can testify first hand the the external clocks on the PB don't work correctly. They tend to sell the PB a few bucks cheaper because you will only buy them once and only once when ...
this makes heavy use of CPU, and I need to use CPU for something else
The issue with this code is that is heavily uses the CPU for busy
waiting rather than for doing useful work. You should try to get rid of
those waiting loops:
Serial.readString(): see Majenko's blog post Reading Serial on the
delayMicroseconds(): for this, you can indeed use a ...