Murata Rotary Position Sensors and Application Design

The rotary position sensor converts the angular movement of the rotor to the change of resistance, which the sensor circuitry further converts into linear changes in output voltage. The Murata Rotary Position Sensors are made extremely durable compared to trim potentiometers. The sensors are made of excellent resistance materials that contribute to a durability up to 1 million cycles. The sensors are dust-proof type 12mm size series and measures only 2.1mm height. With the small package, the rotary sensors offer an electrical rotational angle of 333.3° for a wide range of measurement. The operating temperature range is from -40 to 85 °C.

The rated voltage for the rotary sensors are 5± 0.5VDC. The standard total resistance range is 10k ohm with a full scale (between +/-160 degrees) linearity of ±2%. The resistance change due to temperature coefficient (TCR) is ±500ppm/C.

The high precision and durable rotary position sensors can be used in many applications:

  • Switches for white goods;
  • Wearable devices;
  • Digital still camera;
  • Automotive switches;
  • Car Audio;
  • Multi-function printer;
  • Robot;
  • Motor drive unit;

When using the rotary position sensor for analog-to-digital (A2D) application designs, it is recommended to make sure the input impedance of the A2D interface of the microcontroller is at least 1M ohms to achieve high precision. The 0° index point is located at where the output voltage is 50% of the bias supply as shown in below diagram. From the index point, the rotor sweeps ±160 degrees in either direction.

We designed a circuit using an Atmel ATMEGA32 microcontroller and the Murata rotary position sensor connected to the channel 0 ADC. The output voltages and the corresponding rotational angles are displayed on the 16×2 LCD.

ATMEGA32 ADC with LCD for a rotary position sensor

The following code list can be compiled by gcc or other AVR toolchains.

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