Hello. I am Mekre Mesganaw, an Applications Engineer in Texas Instruments' position-sensing product line. In this video, we will show how to quickly set up and use the TMAG5328EVM, an evaluation module for the TMAG5328 resistor-adjustable low-power Hall effect switch.

The TMAG5328 device is a high-precision, low-power, resistor-adjustable Hall effect switch. When the applied magnetic flux density exceeds the BOP threshold, the device outputs a low voltage. The output stays low until the flux density increases to less than BRP, and then the output drives a high voltage. The device has a low power consumption of 1.4 microamps and can support operation at voltages down to 1.65 volts.

The BOP of the device is set either by connecting a resistor or a voltage source to the ADJ pin device. By following simple formulas, it is easy to calculate what resistor value or voltage value is needed to set up the right BOP value, which can be programmed anywhere from 2 to 15 millitesla. The hysteresis value is fixed, and therefore the BRP value is defined as BOP minus hysteresis. In this case, the BRP is the BOP minus 1 millitesla. With this adjustable threshold feature, the TMAG5328 allows for easy and quick prototyping, fast design-to-market, reuse across different platforms, and easy last-minute modifications in case of unexpected design changes.

The EVM for this device supports setting the BOP dynamically using either the onboard GUI control deck, the onboard potentiometer, or an external voltage source. The EVM also allows installing a resistor to set a fixed value of the BOP instead. The state of the TMAG5328's output may be observed either through the onboard LED or through the GUI. Additionally, the DAC on the EVM has non-volatile memory, which allows the DAC to be programmed to output a user-defined voltage value automatically after reset, thereby allowing the DAC to subsequently set the BOP without requiring a processor. The potentiometer or fixed resistor options may also be used for process operation.

The TMAG5328's power connection is also brought out to a jumper, which allows connection to an amp meter for measuring current consumption or powering the device from a separate power supply from the rest of the board. To use the GUI, a second board is required. This second board is called a sensor controller board, or SCB for short. The SCB is connected to the TMAG5328 and communicates to your computer via USB.

The EVM kit comes with one PCB, a [INAUDIBLE] magnet, and a 3D-printed head-on linear displacement module. To use the GUI, the sensor controller board, or SCB, must also be used, which is sold separately. Before using the GUI, the PAMB Windows USB drivers on the TI-SCB page must be installed by first clicking the Download button shown here. Make sure to run the .asc file as an administrator. This is a one-time only step per computer.

After installing the drivers, the SCB must be programmed, which is also a one-time step. To program the SCB, first connect the EVM to the SCB by connecting the J1 headers of the respective boards together, as shown here. Make sure that the jumper on J3 is connected to the DAC option of the header.

Next, the SCB is connected to the PC using the micro USB cable. We are now ready to launch the GUI, which can be launched from the link in the user's guide or the link on the EVM page. After clicking on the link, the below screen pops up. Close out the README.md dialog box. For first-time use, you may need to install additional drivers for the TI Cloud Agent installation. If these additional drivers are needed, the GUI screen will direct you how to install these drivers.

Next, click Close. Then click File, Program Device, and wait until the device is programmed. After programming the device successfully, the GUI should refresh. Close out the README.md window again.

After completing the steps, confirm the SCB has connected properly. You will see hardware connected in the bottom-left corner of the GUI interface. In addition, a picture of the EVM will be displayed. The GUI's now ready to be used.

The output of a TMAG5328 can be viewed from the Results tab of the GUI or LED D1 on the board. To be the readings used in GUI, click on the Registers tab. Please note that these registers are variables within the microcontroller and are not registers of the TMAG5328.

At the top of the screen, change Auto Read to as fast as possible. Then go to the Results Data tab. The resulting graph shows the output state.

The EVM comes with a head-on linear displacement module with an integrated magnet that applies different magnetic flux density readings to the TMAG5328. To install the module, the prongs on the module are applied from underneath the EVM until they lock into the two holes, as shown here. Unscrewing the inner module of the attachment results in a decrease in magnetic flux density, seen by the sensor, while screwing it in increases the magnetic flux density readings. The inner portion can be screwed or unscrewed using your hands or a screwdriver.

Since the inner module is screwed all the way down in this example, and the magnetic flux density produced when the inner module is fully screwed down is greater than the BOP range of the device, the output of TMAG5328 gets asserted low, which is indicated by LED D1 being turned on the board and the GUI's OUT result graph going to a value of 0. If we unscrew the inner portion of the module and remove it, the magnetic flux density sensed by the device decreases to less than the BRP. When this happens, the output is asserted low to indicate this, and the OUT signal goes back high in the graph.

If you screw this further down, you will see that the LED and graph change when the sensed magnetic flux density passes to BOP. The DAC Configuration tab allows you to configure the DAC to a specific BOP value. This screen offers multiple ways to set the BOP. The first option for setting the BOP is the voltage sweep method. This option is selected by choosing the voltage sweep option in the modification method dropdown box and then clicking change value.

After doing that, you get a DAC voltage sweep in progress screen that shows up. This method says the BOP to the magnetic flux density that is currently sensed by the device. It does this by sweeping the DAC voltage until the output of the TMAG5328 switches from high to low. Sweeping the DAC output takes about 20 seconds. After doing this, the status text bar is updated to new value of the BOP, which is 8.4 millitesla in this case.

The equivalent resistance text box tells you what resist you can connect to the ADJ pin to replace the DAC and still create the same BOP. This allows the DAC to be used for prototyping and the resistor to be used for a low-cost final implementation.

The second method for setting the BOP is done by selecting the manual B option and clicking change value. This allows you to type in the desired BOP you want in the system. In this example, let's say we want a BOP of 10 millitesla. We type in 10,000 in the first text box, and then click change value. If you look at the output graph, notice that the output is high again because the sensed magnetic flux density of 8.4 millitesla is less than the 9 millitesla of BRP that results from setting the BOP to 10 millitesla.

The third method for setting the BOP is done by selecting the manual V option. For this option, you directly enter the output voltage value that you want the DAC to be set to and then click change value. As an example, if you select 160 millivolts, that sets the BOP to about 2 millitesla. Since the sensed magnetic flux density is greater than the BOP of 2 millitesla, the output is asserted low again.

The last option allows you to emulate connecting a specific resistor value to the ADJ pin by using the DAC. To select this option, choose manual R, then enter the ADJ resistor value and click change value. Here, we will emulate adding a 12k resistor value to the ADJ pin.

After doing this, the output is asserted high again since the BRP is greater than the sensed magnetic flux density. If the store to MVM button is pressed, the DAC's non-volatile memory is updated so that the currently set value for the DAC's output voltage, and therefore the BOP, is automatically used after each reset event without requiring a [INAUDIBLE] controller to reconfigure the DAC. In this example, pressing this button results in producing a 12-millitesla BOP after a reset event.

The reload from MVM button allows setting the BOP to what is stored in non-volatile memory. As example, let's set the BOP to 5 millitesla. We can go back to the 12 millitesla setting stored in DAC by pressing the reload from MV button, as shown here. After this store to MVM button on the GUI Is pressed, the sensor controller board is no longer needed to create the desired BOP since the DAC will be automatically initialized to the value stored in its non-volatile memory after each reset. If you want to change the BOP dynamically without using a sensor controller board, another option is to set the BOP using the onboard potentiometer.

To select the potentiometer instead of the DAC, move the J3 jumper from the DAC option to the [? APOP ?] position, as shown here. Moving the potentiometer various the ADJ resistor from 4.3 to 14.3 kiloohms. Moving the potentiometer counterclockwise increases the BOP. Here, we increase the BOP until the BRP is greater than the sensed magnetic flux density, which results in the LED turning off. Now we move the potentiometer clockwise to decrease the BOP until the sensed magnetic flux density is greater than it, which results in the LED turning back on.

If you want to find the resistor value that is currently connected to the ADJ pin, disconnect the power from the board, remove the J3 jumper, and measure the resistance between the [? APOP ?] pin of header J3 to ground. Here, we see this resistance is equal to 4.3 kiloohms. If desired, you can then place the resistor with this measured resistance value, add resistant footprint R7 on the board, and remove the jumper on the J3 header so that you can replace the potentiometer with a fixed resistor. And finally, as an alternative method to setting BOP, an external voltage source can set BOP by connecting its negative terminal to the board's ground and its positive terminal to the middle pin of the J3 header, which is ADJ pin of the 5328.

For more information on the capabilities of this EVM, please visit the TMAG5328EVM user's guide. If you'd like to learn more about our Hall effect sensor portfolio, please visit ti.com/halleffect. to explore our technical resources and product.