Part $3$: Hardware Interrupts using attachInterrupt$()$

Setup:

Connect the pushbutton to pin $2($an interrupt$-$capable pin$).$

Task: Write a sketch that turns on the LED when the button is pressed, using an interrupt to detect the button press. The LED should turn off after $5$ seconds using a timer managed with millis $().$

Code Example:

volatile bool buttonRrtasked $=$ false:

unsigned long startTime $=\backslash 0$;

void setup$()\{$

pinMode$(13,$ OUTPUT$)$;

Attach$\backslash$Aterrupt $($digitalRinTRInterfupt$(2),$ buttonISR, RISING$)$;

$\}$

void loop$()\{$

if $($buttonPressed$)\{$

buttanRressed $=$ false: $//$ Reset flag

digitalWrite$(13,$ HIGH$)$; $//$ Turn on LED

startTime $=$ millis$()$; $//$ Record time

$\}$

$//$ Turn off LED after $5$ seconds

if $($millis$()-$ startTime $>=5000)\{$

digitalWrite$(13,$ LOW$)$; $//$ Turn off LED

$\}$

$\}$

void buttonISR$()\{$

buttonPressed $=$ true;

$\}$

Questions:

How do interrupts differ from polling methods like millis$()$ or digitalRead$()?$

What are the benefits of using interrupts in real$-$time applications?

What does "volatile" keyword in the "volatile bool buttonPressed $=$ false;" declarations do$?$