How to achieve fast, precise, and low power position sensing for real-time control
consumption in battery-powered devices. High accuracy is ensured with the integrated gain and offset correction algorithms, combined with independent temperature correction for the magnet and sensor.
Figure 6: The TMAG5170EVM and the TMAG5273EVM both include a snap-apart board with two different 3D Hall effect sensor ICs (lower right), a sensor control board (lower left), 3D printed rotate and push module (center), and a USB cable to provide power. Image source: Texas Instruments
Figure 4: Gimbal motors in handheld
camera platforms and drones benefit from 3D Hall effect sensors with selectable magnetic field sensitivity ranges. Image source: Texas Instruments
Suggested reading
1. The Fundamentals of Proximity Sensors: Their Selection and Use in Industrial Automation 2. Why and How to Use the Serial Peripheral Interface to Simplify Connections Between Multiple Devices
that supports ±133 mT and ±266 mT. Two user-selected magnetic axes are used for angle calculations. The impact of system mechanical error sources is minimized through magnetic gain and offset corrections. The onboard temperature compensation function can be used to independently compensate for temperature changes in the magnet or the sensor. These 3D Hall effect sensors can be configured through the communications
interface to enable user-controlled combinations of magnetic axes and temperature measurements. The ALERT pin on the TMAG5170, or the INT pin on the TMAG5273, can be used by an MCU to trigger a new sensor conversion. Eval boards aid in getting started Texas Instruments also offers two eval boards, one for the TMAG5170 series and one for the TMAG5273 series, to allow
basic functional evaluations (Figure 6). The TMAG5170EVM includes both the TMAG5170A1 and the TMAG5170A2 models on a snap-apart pc board. The TMAG5273EVM has the TMAG5273A1 and TMAG5273A2 models on a snap-apart pc board. They include a sensor control board that interfaces with the graphic user interface (GUI) to view and save measurements and read and write registers. The 3D printed rotate & push module is used to test common functions of angular
be embedded within enclosures made from nonferrous materials such as plastic or aluminum with the sensing magnets on the outside. Sensors and magnets can also be placed on opposite sides of a pc board Conclusion With the growth of 3D motion and control, designers need to get accurate measurements in real-time, while keeping costs to a minimum through simplified design, while also minimizing power consumption. As shown, the TMAG5170 and TMAG5273 integrated 3D Hall effect sensors address
measurement.
Using the 3D Hall sensors There are a few implementation considerations designers need to be aware of when using these 3D Hall effect position sensors: ■ The SPI readout of the result register in the TMAG5170, or the I²C readout in the TMAG5273, needs to be synchronized with the conversion update time to ensure the correct data is read. The ALERT signal on the TMAG5170, or the INT signal on the TMAG5273, can be used to notify the controller when a conversion is complete and the data is ready ■ A low-inductance decoupling capacitor must be placed close to the sensor pin. A ceramic capacitor with a value of at least 0.01 microfarads (μF) is recommended ■ These Hall effect sensors can
Figure 7: Illustration of the 3D printed rotate and push module mounted on top of the EVM. Image source: Texas Instruments
Figure 5: Except for an SPI interface (shown above) on the TMAG5170 models and an I²C interface on the TMAG5273 models, the internal functional blocks are the same for both families of 3D Hall effect sensor ICs. Image source: Texas Instruments
these issues, offering the flexibility of fast sample rates and low latency for accurate real-time control, or slow sample rates to minimize power
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