This micro controller has several components that interact to provide an interface to the physical world.
The processor requires a stable power supply at 3.3V which is supplied by either battery (2 x AAA) or USB, with a controlling circuit taking 5V from the USB and converting it to 3.3V.
Like all computing devices, the processor’s job is to take inputs and provide outputs according the code loaded to memory.
Both inputs and outputs can work as binary (0 or 3.3V) or analog (the range 0–3.3V), although he processor itself works with 0 or 3.3V only, representing 0 or 1.
It relies on an analog to digital converter (ADC) to change analog inputs, mapping voltage from 0–3.3V to a number between 0 and 1023 (10 bit), or 0 and 255 (8 bit), depending on the connected sensor.
There are many objects in this system such as temperature, magnetic and acceleration sensors, Bluetooth Low Energy radio, and a 5 x 5 matrix of LEDs acting as a “screen”.
Each LED is individually programmable for brightness, and can provide light sensing measured as a reverse polarity voltage, in turn dependent on incident light.
If we take the accelerometer as one exemplar of a subsystem, piezo crystals aligned on three axes 90° apart provide a voltage dependent on strain caused by acceleration or position within a gravitational field. This voltage is presented to the ADC which converts it to a number used to infer the 3D position.
I guess all of the sensors could be considered different classes of the object “sensor” as they all provide a similar function
The bluetooth radio object behaves like the ADC in that it changes supplied voltages to a variation of the frequency of a radio wave, whereas the ADC changes voltages into a series of bits