How to Use AS5048 Magnetic Encoder Position Sensor: Examples, Pinouts, and Specs

The AS5048 is a precise magnetic rotary encoder sensor that provides a full 360-degree range of angle measurement. It is designed to output the absolute position of the magnet's rotation angle via a digital interface, which can be SPI (Serial Peripheral Interface) or I2C (Inter-Integrated Circuit), depending on the variant of the sensor. This sensor is commonly used in robotics, motor control, and other applications where accurate angular measurements are critical.

• Resolution: 14-bit (16384 positions per revolution)
• Interface Options: SPI or I2C
• Supply Voltage: 3.3V to 5V
• Maximum Rotation Speed: 14,000 rpm (revolutions per minute)
• Operating Temperature Range: -40°C to +125°C

1. Connect VDD to a 3.3V or 5V power supply.
2. Connect GND to the system ground.
3. For SPI communication, connect SCL/CLK to the SPI clock, SDA/DO to the SPI MISO (Master In Slave Out), and NCS to the SPI chip select on your microcontroller.
4. For I2C communication, connect SCL/CLK to the I2C clock and SDA/DO to the I2C data line. Set the A1 and A2 pins to the desired address configuration by connecting them to either VDD or GND.

• Ensure that the magnet used is within the specified range of the sensor for accurate readings.
• Avoid placing any ferromagnetic materials near the sensor as they can interfere with the magnetic field and distort readings.
• Use proper decoupling capacitors close to the power supply pins to minimize power supply noise.

#include <SPI.h>

// Define the AS5048A SPI settings
SPISettings AS5048ASettings(1000000, MSBFIRST, SPI_MODE1);

// Define the chip select pin
const int CSPin = 10;

void setup() {
  // Set the chip select pin as an output
  pinMode(CSPin, OUTPUT);
  // Begin SPI communication
  SPI.begin();
  // Pull the chip select pin high to deselect the sensor
  digitalWrite(CSPin, HIGH);
}

void loop() {
  // Read the angle from the sensor
  unsigned int angle = readAS5048A();
  // Print the angle to the Serial Monitor
  Serial.println(angle);
  delay(1000); // Wait for 1 second
}

unsigned int readAS5048A() {
  // Variable to store the angle
  unsigned int angle = 0;
  // Pull the chip select pin low to select the sensor
  digitalWrite(CSPin, LOW);
  // Start SPI transaction with the defined settings
  SPI.beginTransaction(AS5048ASettings);
  // Send the command to read the angle
  SPI.transfer(0xFF);
  // Read the high byte of the angle
  angle = SPI.transfer(0x00);
  // Shift the high byte and read the low byte
  angle = (angle << 8) | SPI.transfer(0x00);
  // End the SPI transaction
  SPI.endTransaction();
  // Pull the chip select pin high to deselect the sensor
  digitalWrite(CSPin, HIGH);
  // Return the angle
  return angle;
}

• Inaccurate Readings: Ensure that the magnet is properly aligned and there are no ferromagnetic materials nearby that could affect the sensor's readings.
• No Data on SPI/I2C: Check the connections and ensure that the correct communication protocol is being used. Also, verify that the chip select pin is being controlled correctly for SPI.

• Power Supply Issues: Use a multimeter to check that the power supply is within the specified range and is stable.
• Signal Integrity: Use an oscilloscope to check the integrity of the SPI or I2C signals. Look for noise or distortion that could affect communication.
• Magnet Placement: Adjust the position of the magnet relative to the sensor to ensure it is within the optimal range for detection.

Q: Can the AS5048 be used with a 5V microcontroller? A: Yes, the AS5048 can be interfaced with both 3.3V and 5V systems.

Q: How can I change the I2C address of the sensor? A: The I2C address can be changed by configuring the A1 and A2 pins to either high or low (VDD or GND).

Q: What is the maximum distance the magnet can be from the sensor? A: The optimal distance is typically a few millimeters, but it can vary based on the magnet's strength and size. Refer to the sensor's datasheet for specific recommendations.