Angle 4 Click is an angular magnetic rotary sensor, which can be used as a rotary encoder. With the help of the AEAT-8800-Q24, an integrated 10 to 16-bit programmable angular magnetic encoder, the Angle 4 Click can sense the magnetic field rotation aligned with the center of the sensor, over the whole range of 360°. The absolute angular position can be read from the SPI interface. The sensor IC itself offers a versatile contactless rotation sensing platform, with the ability to fine-tune several important working parameters, such as the resolution, zero position, direction, hysteresis, and more.
The AEAT-8800-Q24 IC utilizes integrated Hall sensor elements, accompanied by very sophisticated circuits for processing analog and digital signals, resulting in a very robust and precise rotary sensing interface. This makes Angle 4 Click an ideal solution for a wide variety of contactless angle measurement applications, such as the acquisition of position and rotation for various BLDC or stepper motors, mechanical potentiometer replacement, for building various HMI platforms, in robotics, and similar applications.
As already mentioned, Angle 4 Click uses the AEAT-8800-Q24, an integrated 10 to 16-bit programmable angular magnetic encoder, by Broadcom. This sensor relies on integrated Hall elements and complex analog front end and digital signal processing, in order to provide absolute angular position over the industry standard SPI interface. The user has the ability to programmatically set the zero position, direction, hysteresis, and the resolution. This allows the Click board™ to be tailored according to needs for a range of different applications.
The possibility to sense the rotational angle of a diametrically magnetized object parallel with the Click board™ surface, gives an opportunity to develop both contactless rotational and positional measurement applications, as well as the human-machine interfaces (HMI), such as the rotary encoders, digital potentiometers, and similar. The calibration is simple, and the AEAT-8800-Q24 datasheet provides a detailed explanation how to calibrate the device by using a diametrically magnetized object (i.e. a magnetic disc), with its axis aligned to the center of the sensor. For the best results, the magnet properties should be according to specifications in the datasheet. Once calibrated, it can be permanently used, with no additional recalibrations.
The AEAT-8800-Q24 uses the non-volatile one-time programming memory during the operation. It contains registers with the calibration values, zero offsets, resolution and so on. All the OTP locations have their shadow locations, which allow writing, but only when the unlock command is issued (writing 0xAB to the location 0x10). However, the values will be lost after the power cycle and will be rewritten with the values contained in the OTP memory.
The library provided with Angle 4 Click offers several simple and useful functions, among which is the angle4_calibration function, which will automatically program the direction and the resolution parameters to the OTP memory, passed as argumetns to this function. However, the OTP memory will not be permanently written, unless appropriate programming voltage is applied to the VDDP pin. Since the OTP memory can be programmed only once, a thorough understanding of the OTP programming process is required. More information about the OTP programming process can be found in the AEAT-8800-Q24 datasheet.
The Click board™ contains an SMD jumper, labeled as PWR SEL, which can be used to set the operating voltage of the Click board™ to either 3.3V or to 5V. This allows a wide range of different MCUs to be interfaced with the Click board™, operating both at 3.3V and 5V.
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