Possible Sensors

display status:
  blue LED
    => own pet is currently on this device
  RGB LED (neopixel)
    => visualizes pets emotions (also works while pet is away)

keep track of time:
  RTC
    => day/night cycle
    => time-based events
    => create a log of previous actions and their time

measure environment:
  temperature sensor
    => pet has to be warmed up/cooled down
  (humidity sensor)
    => pet is unable to be walked outside when humidity is too high
  (light sensor)
    => more active during bright environments
  (proximity sensor)
    => pet detects owner
      => pet wakes up from sleep
      => pet gets happy if already awake
    => pet can be petted

track orientation:
  | gyro
  | accelerometer
  | (magnetometer)
  => wake the pet up
  => move pet when device is tilted
  => pet moves when device is in motion
    => optional: pedometer