microcontrollers

pins

GPIO: digital HIGH/LOW; many have PWM
ADC: analog in (e.g., 0–3.3 V → 0–4095)
UART / I²C / SPI: talk to chips & sensors


// Arduino button → LED (pull-up)
const int LED = 5, BTN = 2;

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(BTN, INPUT_PULLUP);
}

void loop() {
  digitalWrite(LED, !digitalRead(BTN));
}

caution

mind logic levels (3.3 V vs 5 V). add level shifters where needed.

try this

start with serial prints; logging is the fastest debugger.