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RC circuit driven by square wave

Periodic oscillation of capacitor voltage RC network driven by 0.05 Hz squarewave

Breadboard circuit with Arduino generating a square wave output that drives an RC network.

//
// capacitor.ino - written by Ted Burke - 30-Nov-2022
//
// Generates a 0.05 Hz square wave (T = 20 s) on D3
// to periodically charge and discharge an RC network.
// The capacitor voltage v_c is sampled on A0 (f_s ≈ 10 Hz)
// and printed for plotting in the Serial Plotter.
//

void setup()
{
  Serial.begin(9600);

  pinMode(3, OUTPUT);
}

void loop()
{
  float v_c;  // capacitor voltage in volts

  // Square wave output on D3, T = 20 s, f = 0.05 Hz
  digitalWrite(3, millis() % 20000 > 10000);

  // Sample v_c on analog input A0, convert from du to volts and print
  v_c = analogRead(0) * (5.0 / 1023.0);
  Serial.println(v_c);

  delay(100); // 100 ms delay
}