A lightweight, robust, and cross-platform library for the SCT013 Series Non-Invasive Current Sensors.

Designed to be simple for beginners yet powerful for advanced IoT applications (ESP32/Blynk/WiFi).

• Auto-Configuration: Automatically detects if you are compiling for Arduino (5V, 10-bit) or ESP32 (3.3V, 12-bit) and adjusts math accordingly.
• Precision Timing: Samples for exactly 10 line cycles (e.g., 200ms @ 50Hz) to ensure stable RMS readings regardless of loop speed.
• Digital Smoothing: Built-in helper to stabilize jittery readings (smooth() method).
• Zero/Tare: Non-blocking tareNoDelay() function to remove DC offset on the fly.
• Calibration Utility: Includes a sketch to fine-tune your sensor against a multimeter using Serial commands.
• Non-Blocking Mode: Includes an update() method so you can read current without stopping your main loop.

1. Download this repository as a .zip file.
2. Open Arduino IDE -> Sketch -> Include Library -> Add .ZIP Library...
3. Select the downloaded zip.

This library works best with the following circuit topography:

• Sensor: SCT013-100 (or similar) connected to an analog pin.
• Burden Resistor: 18Ω or 33Ω (18Ω recommended for ESP32/Arduino cross-compatibility).
• Bias Circuit: Two 10kΩ resistors (Voltage Divider) + 10uF Capacitor.

Best for basic monitoring where the sensor is the main priority.

#include <SCT013.h>

// Connect Output to Analog Pin (A0 for Arduino, 34 for ESP32, etc.)
SCT013 sensor(A0);

void setup() {
  Serial.begin(115200);
  
  // Calibration: 2000 turns, 18 ohm burden resistor
  sensor.begin(2000, 18);
}

void loop() {
  // Read RMS Current (Calculates over 10 line cycles)
  double amps = sensor.readAmps();
  
  Serial.print("Current: ");
  Serial.print(amps);
  Serial.println(" A");
  
  delay(1000);
}

Best for IoT projects where you need to keep WiFi/Display active.

#include <SCT013.h>

SCT013 sensor(A0);

void setup() {
  Serial.begin(115200);
  sensor.begin(2000, 18);
}

void loop() {
  // Call update() as fast as possible in your loop
  // It returns TRUE when a fresh reading is ready (every ~200ms)
  if (sensor.update()) {
    double amps = sensor.getLastAmps();
    
    Serial.print("Current: ");
    Serial.println(amps);
  }
}

This library comes with a powerful Calibration Sketch (examples/Calibration/Calibration.ino). Upload it to your board to fine-tune your readings via Serial Monitor.

Supported Commands:

• t (Tare): Zeros the sensor (removes DC offset).
• c (Calibrate): Enter the Real Amps from your multimeter, and the storage automatically calculates the new factor.
• r (Reset): Enter your burden resistor value (e.g., 18 or 33) to reset calibration to theoretical defaults.
• s (Smooth): Adjust the smoothing filter weight (0.1 = Fast, 0.9 = Slow/Stable).

Constructor. Automatically detects board voltage and ADC resolution.

Initializes the sensor parameters.

• turns: The number of turns using in the CT (e.g., 2000).
• burdenOhms: The value of your burden resistor (e.g., 18 or 33).

Sets the mains frequency for timing calculations.

• hz: 50 or 60. (Default: 50).

Blocking. Samples for 10 full cycles and returns the RMS Amps. Recommended for highest accuracy if blocking is okay.

Non-blocking. Call this in loop(). Returns true when a new reading is available.

Returns the most recent current reading calculated by update().

Initiates a fast-convergence filter to re-center the DC offset (Zero point). Call this if your readings drift when no load is connected.

Helper function for Exponential Moving Average (EMA) smoothing.

• newVal: The latest reading.
• oldVal: The previous smoothed value.
• weight: The "heaviness" of the old value (0.0 - 1.0).
  • 0.9: Very smooth, slow response.
  • 0.2: Fast response, less smoothing.