Angle Click is a precise Hall-effect angle sensing Click board™ that can be used to measure the rotational angle of the magnetic field in the X-Y plane above it (parallel to the surface of the Click), through the whole range of 360°. The Click yields very precise results for both off-axis and axis operation, which make it a perfect choice for precise measuring of the rotational angle in a wide range of different high-speed applications, for example in the automotive industry: electronic power steering, transmission, torsion bar, or the motor shaft rotation.

Angle Click features the A1335 Hall-effect angle sensing IC, made by Allegro MicroSystems LLC. This IC measures the magnetic field angular vector, based on the actual physical reading of the integrated Hall-effect sensor, as well as the user selected parameters, such as the digital filtering, dynamic range and scaling. The integrated 32bit MCU ensures that the processed data is delivered with a minimal delay and it has enough power to provide the complex processing of the input values so that the measurement remains fast, precise and linear.

Angle Click carries the A1335 Hall-effect angle sensing IC, which is actually a SoC architecture type of integrated circuit. It features a Circular Vertical Hall (CVH) technology, a high-speed sampling AD converter, MCU for the data processing and the section used for the I2C/SPI communication. Besides the SRAM registers which can be accessed by the I2C or the SPI, the IC features an EEPROM memory, used to permanently store configuration data. The device comes pre-programmed with the factory default register values, so it can properly operate in most cases. The detailed instructions on how to program the EEPROM memory can be found in the [A1335 programming manual](link text).

The rotation of the magnetic field is detected by the CVH sensor. This sensor detects the magnetic field presence by utilizing the effect the magnetic fields produces to the electron flow within the sensor, while the current flows through it - the Hall effect. The signal from the sensor is then digitized by the AD converter and handed to the digital front end of the IC. The digitalized signal is preconditioned, processed through the bandpass filter and the raw value of the angle is calculated. The value is then forwarded to the MCU unit. It is submitted to various steps of processing, depending on the register values set by the user. The more processing is done by the MCU, the less responsive the reading will be. MCU can perform several types of resource-demanding processing. Some of the algorithms that can be applied to the raw signal are:

• Angle averaging - the data is collected and averaged, depending on the selected output rate.
• IIR Filtering - the multi ordered filter can be applied to the raw values, with the selectable coefficient
• Gain Offset and Gain Adjust - allows setting the gain adjusting for a better resolution and zeroing out the raw rotation value.
• Angle Clamping - useful when rotation is less than 360°, this will limit the output values to the clamping ones.
• Harmonic Linearization - used to apply a user-defined error correction to the angle value.

These are just some of the options that can be set. The A1335 datasheet contains a detailed description for all of these functions. The required settings can be set via the registers and then used for the optimal measurement profile. The Click can use either SPI or I2C for the communication. This can be set by the SMD jumpers. More about jumpers setting can be found in the Onboard settings and indicators table, below.

• Interface: I²C, SPI
• Compatibility: mikroBUS™
• Dimensions: 42.9 x 25.4mm
• Input Voltage: 3.3V, 5V

• Schematic
• A1335 Datasheet
• A1335 Programming Manual
• mikroSDK
• GitHub