Learn Angle Detection Using A5020 Sensor and Arduino | Wiring, Code & Output

How to Use A5020 Angular Sensor with Arduino for Precise Angle Measurement

Learn how to interface the A5020 Angular Position Sensor with Arduino. Step-by-step guide with circuit, code, and working explanation for accurate angle measurementt

Introduction

In this tutorial, we’ll explore how to read angular position data using an Arduino and the A5020 Angular Position Sensor. Angular sensors are widely used for precise linear and rotational position detection, serving as an excellent alternative to traditional potentiometers.

The AS5020 is a 6-bit absolute angular position sensor that works with a simple magnetic source placed on its surface. It provides 64 unique angular positions over a full 360° range. Inside the sensor, a Hall sensor array, signal conditioning, and digital post-processing generate a 6-bit binary output. This data can be easily accessed through the Synchronous Serial Interface (SSI), making it ideal for accurate and stable angle measurement in Arduino projects.

🔹 Understanding Zero-Position Programming in AS5020

The Zero-Position Programming, feature in the AS5020 Angular Sensor lets you define a custom reference or “zero” point for your application. Normally, the sensor outputs angle data from a factory-set zero position, which might not align exactly with your mechanical setup or the initial position of the magnet.

With zero-position programming, you can permanently set your own zero reference — that is, the point at which the output angle should start counting from 0°. This is especially useful when:

1. The magnet isn’t perfectly centered during assembly.
2. You need to align mechanical zero (like a motor shaft or lever) with electrical zero (sensor output).
3. You want to calibrate the system to a specific start angle.

Once programmed, the AS5020 internally adjusts its output so that this new zero point corresponds to 0°, and all following readings are measured relative to it.

Initial angular orientation

⚠️ Important: This programming can only be done once — it’s a one-time permanent operation stored inside the sensor’s non-volatile memory. So, make sure the magnet and sensor are properly aligned before performing the zero-position programming.

🧭 How the A5020 Works

The A5020 uses a Hall sensor array to detect the magnetic field from a small magnet placed above it. As the magnet rotates, the sensor measures the direction of the magnetic field vector and converts it into a 6-bit digital angle (0 – 63).

Each increment represents 360° / 64 = 5.625° per step. This data is then sent serially to the Arduino through the SSI interface.

1. The Arduino generates clock pulses to request data.
2. The A5020 responds by sending out the 6-bit angle data, followed by the NVR and Parity bits.
3. The Arduino reads these bitsto determine the current angular position of the magnet..

This allows you to create compact and contactless angular measurement systems for robotics, motor position feedback, or encoder replacement projects.

Pin Configuration

Pin No	Pin Name	Description
Pin 1	DATA	Serial data output of the SSI. When PD/CSn = 0, the sensor shifts out the 6-bit angle data (MSB first) with CLK pulses, followed by NVR and even parity bits. NVR = 1 indicates an invalid magnetic field range.
Pin 2	VDD	Positive Supply Voltage.
Pin 3	VSS	Negative Supply Voltage (GND)
Pin 4	PROG	Programming Input. This pin is used to program the zero position into a non-volatile memory (One Time Programmable). The programmed value is subtracted from the actual measured angle. (This pin is also used for Data In during Daisy-Chain function)
Pin 5	N. C	Not Connected during operation. This pin is for manufacturers use only.
Pin 6	N.C	Not Connected during operation. This pin is for manufacturers use only.
Pin 7	PD/CSn	Power Down Input, Disable or Chip Select (active low). PD/CSn=0 activates the device and enables the measurement. PD/CSn=1 sets the device in power save mode and puts the DATA pin in high impedance (high Z) state.
Pin 8	CLK	CLOCK Input of the SSI.Pin 8 serially clocks out the measured angle data at Pin 1 (DATA).

Basic Diagram

Interface with Arduino

Optional: Use a pull-up resistor (10kΩ) on the DATA line for stable communication.

    
          const int clkPin = 2;
          const int dataPin = 3;

          void setup() {
            pinMode(clkPin, OUTPUT);
            pinMode(dataPin, INPUT);
            Serial.begin(9600);
          }

          int readAngle() {
            int angle = 0;
            digitalWrite(clkPin, LOW);
            for (int i = 0; i < 6; i++) { // Read 6-bit data
              digitalWrite(clkPin, HIGH);
              delayMicroseconds(1);
              angle = (angle << 1) | digitalRead(dataPin);
              digitalWrite(clkPin, LOW);
              delayMicroseconds(1);
            }
            return angle;
          }

          void loop() {
            int angleValue = readAngle();
            Serial.print("Angle: ");
            Serial.println(angleValue);
            delay(500);
          }

    

Applications of Angular AS5020 sensor

Robotics:
Detecting joint or wheel rotation

Motor Control:
Position feedback for servo or stepper motors

Industrial Automation:
Angle measurement in assembly lines

DIY Electronics:
Replacing potentiometers for precise angular detection

Conclusion

The AS5020 sensor is a reliable and compact solution for angle detection. With simple Arduino integration via SSI protocol, you can accurately read angular positions for robotics, motor control, and other precision applications.