Adjustable Step-down Module 3-40VDC 1.5-35VDC LM2596

// Canonical example for an LM2596 adjustable step-down module
// This sketch reads the Arduino's 5V rail as a simple voltage check.
// Wiring note: the LM2596 is connected to the Arduino power rails in this example.

void setup() {
  Serial.begin(9600);
  while (!Serial) {
    ;
  }
  Serial.println("LM2596 adjustable step-down module example");
  Serial.println("The module is wired to the Arduino power rails.");
}

void loop() {
  int raw = analogRead(A0);
  float volts = raw * (5.0 / 1023.0);

  Serial.print("A0 reading = ");
  Serial.print(raw);
  Serial.print("  approx volts = ");
  Serial.println(volts, 3);

  delay(1000);
}