Working set:
-ATtiny45: small (66mHz peripheral clock-good for highspeed PMW, 5 I/O pins, go for 4kB)
-ATtiny44: medium (less good for PMW, 11 I/O pins, 16-bit timer)
-ATmegaxx8: large (20 I/O pins, USART, 3 timers, 16kB memory): 48, 88, 168, 328 -> just extra program memory
-extra variants: ATmega168PA-10PU, ATmega168-AU...
  -V: run at low voltage / reduced speed (less good)
  -P&V: older
  -A&PA: newer, run full range on speed and voltage / less power (P) -> good bet
  -extension: package size:
    -PU/PDIP: largest/through hole
    -AU/TQFP: 1.0mm spacing surface mount (SMT)
    -MU: hard to solder by hand
  -number in extension: speed grade (run up to x MHz), no number: 20MHz at 5V (full rated speed)
  

Pins in groups of 8
statePins = PINB;
PORTB = 42; (assignment)

Core:
-CPU
-Memory: flash (doesn't disappear when power goes out), RAM, EEPROM
-Clock (8MHz) -> CPU clock at 1MHz / multiple clocks derived from master clock source
-Output pins: display either VCC or GND voltage (analog get from PWM)
-Input pins: greater or lower than VCC+GND/2


Input:
Button: VCC to button & input pin / other side of button to GND through resistor

Peripherals:
-Serial communication:
  -Plain-vanilla USART (computer, GPS etc)
  -SPI (ultra-fast & short distance)
  -12C (moderate amount, accelerometers for ex)
-Analog to Digital: ADC (oversampling and exponential smoothing)
-Interrupt service routine (drops current, executes when condition met and resumes)
-Timers/counters: count pin activation (timer when hooked to clock, and output to OC pins for subroutines)