Introduction
With the increasing adoption of renewable energy systems and smart energy management solutions, monitoring both the magnitude and direction of electrical current has become essential. In applications such as photovoltaic (PV) systems, energy can flow either from the grid to a load or from a local generation source back to the grid. Therefore, a reliable and cost-effective method of measuring AC current and determining its direction is required for efficient energy monitoring and control.
This project, “AC Current Direction & Measurement with Arduino Pro Micro,” presents a simple and non-intrusive solution for measuring alternating current and identifying the direction of power flow. Using an Arduino Pro Micro, the system samples voltage and current signals, calculates their RMS values, and analyzes their phase relationship to determine whether energy is being consumed or injected. The design incorporates zero-crossing detection techniques, hardware-assisted direction sensing, and a filtered PWM output for analog signal generation, making it suitable for smart home automation, renewable energy monitoring, and educational applications.
Objectives
- To measure AC current flowing in a circuit using a suitable current sensor.
- To determine the direction of current flow in real time.
- To process sensor signals using the Arduino Pro Micro microcontroller.
- To display or transmit the measured current value for monitoring purposes.
- To ensure accurate measurement of both magnitude and polarity (direction) of AC current.
- To develop a low-cost, compact, and efficient current monitoring system.
- To improve understanding of AC signal behavior and microcontroller-based sensing systems
PCB Manufacturer
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Circuit Diagram
This circuit is designed to measure AC current, AC voltage, and determine the direction of power flow using an Arduino Pro Micro. The system uses an SCT013-000 current transformer (CT) to sense the load current and a ZMPT101B voltage transformer to measure the AC mains voltage. Both signals are conditioned and amplified using OPA2333 operational amplifiers, then shifted around a precise 2.5V reference voltage so that the Arduino can safely read the AC waveforms through its analog inputs. A built-in 24V to 5V buck converter powers the entire circuit, ensuring stable operation of the microcontroller and analog components.
To determine the direction of current flow, the circuit compares the phase relationship between the voltage and current waveforms. Zero-crossing detection circuits generate timing signals for both voltage and current, allowing the Arduino to calculate the phase difference between them. Based on which waveform leads or lags, the controller can identify whether power is flowing from the source to the load or in the reverse direction. The measured values are processed by the Arduino and can also be converted into a standard 0–10V analog output, making the system suitable for energy monitoring, industrial control, and smart power measurement applications.
PCB Image
3D View
Manufacturing Files
Gerber
Bill Of materials
Pick and Place File
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Conclusion
The project “AC Current Direction & Measurement with Arduino Pro Micro” successfully demonstrates a practical method to measure both the magnitude and direction of AC current using a microcontroller-based system. By integrating a current sensing module with the Arduino Pro Micro, the system is able to accurately process real-time electrical signals and provide meaningful output for monitoring applications.
This project improves understanding of AC signal behavior, sensor interfacing, and embedded data processing. It also offers a compact, low-cost solution for current monitoring that can be further expanded for energy monitoring, fault detection, or smart metering applications in the future.
