Section Summary: LED Projects and Digital Input

Activities 2.4 – 2.7. Use this to review, or to fill in a definition you missed.

1. Sequencing Output

Several LEDs, each on its own pin, become a sequence once the code decides the order and the timing.

Cumulative Sequence: A sequence where each new step joins the ones before it, instead of replacing them.

2. Writing Your Own Functions

When the same few lines keep reappearing, give them a name. A parameter then lets that one definition handle every variation.

Function: A named, reusable block of code.
def: The keyword that starts a function definition.
Parameter: A placeholder variable in a function definition, filled in with a real value each time the function is called.
Call: Actually running a function by writing its name followed by parentheses.

3. Groups of LEDs

A list can hold objects, not just numbers. Putting your Pin objects in one list lets a single loop animate all of them.

LED Array: A row of LEDs treated as one group instead of as separate lights.
List of Objects: A list whose elements are objects rather than plain numbers or strings — here, one Pin per LED.
Animation: A pattern of on/off states separated by pauses, producing the illusion of movement.

4. Reading a Button

A pin can be read instead of driven. An unconnected input floats, so a pull-down holds it at 0 until the button says otherwise. A function that measures something should hand the number back with return.

Digital Input: A pin the board reads instead of drives, giving 0 or 1.
Pull-Down Resistor: A resistor holding an input pin at 0 when nothing else is driving it. The board has one built in, switched on with Pin.PULL_DOWN.
Return Value: The value a function hands back to whoever called it, using return.
False Start: Pressing before the signal — an attempt that must not be counted as a reaction time.