Is extra hardware and components needed to connect the bare MCU directly to a PCB, without a shield? As a hobbyist I code in a variety of arduino's and in Digispark's (Attiny 85 and 167).
But I'm doing a project with space contraints, so I'd need to use just the MCU directly over my pcb.
Apart from a voltage regulator (to get the VIn to 5V or 3.3V) do I need extra components to mount the MCU to my PCB?
DO I need crystals, capacitors, etc? Or the MCUs (mostly AtMega 32u4 and Attiny85 and Attiny167) have it all what's needed inside them?
I'll program the MCU before soldering on to the PCB, so there's no need for USB or programming stuff or leds.
Thanks!
DO I need crystals, capacitors, etc? Or the MCUs (mostly AtMega 32u4 and Attiny85 and Attiny167) have it all what's needed inside them?

You don't need a crystal if you use the internal clock of the MCU (which means setting the fuses right and compiling your code to expect the right clock frequency). However if you are using a direct USB interface (such as for the ATMega32U4) then you will need a crystal as the precise timing is required for USB to operate.
You will need capacitors. Decoupling capacitors on all the power pins are not optional and must be included.
You will need a pullup resistor on the RESET pin unless you have set the fuse to disable the RESET pin (not advisable since it will prevent ICSP programming in the future - but can be useful for low pin-count chips).