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What should the state of the LEDs be at start up or zero G?

Category: Hardware
Product Number: 2-Axis Tilt sensor Lab

I have followed this lab: 2_axis_tilt_sensor

I am using the ADALM1000 instead of 2000 and I have also used a small voltage inverter from Polulu to get -5v as well as +5 into the comparator side of the circuit as the ADALM1000 cannot produce a negative voltage. I am using 3.3v from ADALM1000 to power the sensor itself.

I am having the problem that the LEDs that go from the non-inverting OUT of both AD8561s (pins #7) are on at start-up. In the picture, they are the green LEDs. Is this the right behaviour? Should all the LEDs be off at start-up?

Any help or feedback would be appreciated. This lab is also available in the Studentzone vol. 57 No.3-September 2023

Here is a picture of my breadboard. Note: I am using LEDs with built-in resistors: My tilt sensor lab with ADALM1000

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  • Here are my thoughts on doing this activity with the M1k vs M2k.

    First, the AD8561 should not need a negative supply as long as the +In and -In pins are positive. You should be able to connect V- to GND.

    In figure 5 it shows the ADXL372 powered from W1 of the M2k. I assume you are powering the XL372 from the +3.3 V output on the digital connector of the M1k?

    To debug your setup, have you measured the voltage being output on the Xout and Yout pins of just the XL372 as in figure 3? This should tell you what the at rest state of the sensor is. Next, what voltage are you sending to the -In pins of the 8561 (W2 in figure 5)? How does this compare to the voltages you measured on the XL372 X and Y outputs. This info will tell you which of the LEDs should be on or off. The two outputs of the 8561 are complements of each other. So one will be "on" and the other "off" depending on the differential voltage between the +In and -In pins.

    To learn more about how the 8561 works take a look at this activity:

    https://wiki.analog.com/university/courses/alm1k/alm-lab-comp

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  • Here are my thoughts on doing this activity with the M1k vs M2k.

    First, the AD8561 should not need a negative supply as long as the +In and -In pins are positive. You should be able to connect V- to GND.

    In figure 5 it shows the ADXL372 powered from W1 of the M2k. I assume you are powering the XL372 from the +3.3 V output on the digital connector of the M1k?

    To debug your setup, have you measured the voltage being output on the Xout and Yout pins of just the XL372 as in figure 3? This should tell you what the at rest state of the sensor is. Next, what voltage are you sending to the -In pins of the 8561 (W2 in figure 5)? How does this compare to the voltages you measured on the XL372 X and Y outputs. This info will tell you which of the LEDs should be on or off. The two outputs of the 8561 are complements of each other. So one will be "on" and the other "off" depending on the differential voltage between the +In and -In pins.

    To learn more about how the 8561 works take a look at this activity:

    https://wiki.analog.com/university/courses/alm1k/alm-lab-comp

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