MIKROE Compass 4 Click is a compact add-on board that can measure the three-axis magnetic field that is perfect for implementation in applications such as electric compasses. This board features AK09915, a complete 3-axis magnetic sensor with signal processing from AKM. For obtaining the sensor measurement data of the magnetic field, an I2C or SPI protocol can be used. The main feature of the sensor is the capability to measure magnetic fields within the full-scale range of ±4912 μT, with a sensitivity of 0.15 µT per LSB, resolution at 16bits, and built-in Noise Suppression Filter (NSF), enabling high measurement accuracy for electronic compass applications. This Click board™ is suitable for applications such as an electrical compass, position sensing, general magnetic field measurement, and more.

Compass 4 Click is based on the AK09915, a complete 3-axis magnetic sensor with signal processing from AKM. The AK09915 incorporates magnetic sensors for detecting terrestrial magnetism in the X-axis, Y-axis, and Z-axis, a sensor driving circuit, signal amplifier chain, and an arithmetic circuit for processing the signal from each sensor. The output signal of each axis sensor is multiplexed, pre-amplified processed, and digitized by a 16-bit A/D converter (ADC). A three-axis magnetometer can be programmed to measure the magnetic component for each axis, within the full-scale range of ±4912 μT and sensitivity of 0.15 µT per LSB.

The AK09915 has an analog circuit, digital logic, and interface block integrated on a chip. It also supports nine different Operation Modes that can be chosen by setting the appropriate registers. When the Single Measurement Mode is set, the magnetic sensor measurement starts. After magnetic sensor measurement and signal processing is finished, measured magnetic data is stored in measurement data registers, and then the AK09915 transits to Power-Down Mode automatically. On transition to Power-Down Mode, Data Ready (DRDY) bit turns to “1”. When any of the measurement data registers are read, the DRDY bit turns to “0”. It remains “1” on the transition from Power-Down Mode to another Mode. Data Ready output pin of the AK09915 labeled as the DRY is routed to the INT pin of the mikroBUS™ socket. Besides Data Ready pin, this Click board™ also has the Reset pin (RST), routed to the appropriate position on the mikroBUS™.

Compass 4 Click provides the possibility of using both I2C and SPI interfaces with a maximum frequency of 2.5MHz for I2C and 4MHz for SPI communication. The selection can be performed by positioning SMD jumpers labeled as COMM SEL to an appropriate position. Note that all the jumpers must be placed to the same side, or else the Click board™ may become unresponsive. While the I2C interface is selected, the AK09915 allows the choice of the last two significant bits (LSB) of its I2C peripheral address. This can be done by using the SMD jumper labeled as ADDR SEL. Depending on the positions of each of the ADDR SEL jumpers, four different addresses can be set.

This Click Board™ is designed to be operated only with a 3.3V logic level. A proper logic voltage level conversion should be performed before the Click board™ is used with MCUs with different logic levels.

• Interface: I²C, SPI
• Compatibility: mikroBUS™
• Dimensions: 28.6 x 25.4mm
• Input Voltage: 3.3V
• Supply Voltage: Min. -0.3V, Typ. 3.3V, Max. 3.6V
• Sensitivity: 0.15 µT/LSB
• Full Scale Measurement Range: ±4912 μT
• Resolution: 16bit
• Operating Temperature Range: Min. -30°C, Max. +85°C

• Schematic
• AK09915 Datasheet
• mikroSDK
• GitHub