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SSong.2
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August 31, 2022
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I would like to use iis2dh to detect motor vibration with following use case. Is it possible to generate interrupt from deep sleep when vibration detected by iis2dh?

  • August 31, 2022
  • 1 reply
  • 867 views

I would make the IoT device that detect vibration of the FAN.

I will use this industrial portable blower FAN .

https://www.indiamart.com/proddetail/portable-blower-fan-15055431262.html

Scenario

1. To saving the energy of the device, the device goes to deep sleep when FAN is not working.

2. the device is activated by interrupt from iis2dh when FAN is start to working.

My question is that

#01.

Is it possible to generate interrupt from deep sleep when vibration detected by iis2dh?

#02.

for more sophisticated solution, is it more good to use microphone such as MP23AB01DH ?

    This topic has been closed for replies.
    Best answer by Eleon BORLINI

    Hi @SSong.2​ ,

    #01.

    Is it possible to generate interrupt from deep sleep when vibration detected by iis2dh?

    As described in the datasheet p.18, you can set peak and duration of the signal waking up the device. You might tune the peake and the duration according to the fundamental frequency of your vibration, if not too high (duration is proportional to the selected ODR).

    The IIS2DH can be programmed to automatically switch to low-power mode upon recognition of a determined event. Once the event condition is over, the device returns back to the preset normal or high resolution mode. To enable this function the desired threshold value must be stored inside the Act_THS (3Eh) register while the duration value is written inside the Act_DUR (3Fh) register. When the acceleration falls below the threshold value, the device automatically switches to low-power mode (10Hz ODR). During this condition, the ODR[3:0] bits and the LPen bit inside CTRL_REG1 (20h) and the HR bit in CTRL_REG3 (22h) are not considered. As soon as the acceleration rises above threshold, the module restores the operating mode and ODRs as determined by the CTRL_REG1 (20h) and CTRL_REG3 (22h) settings.

    #02.

    for more sophisticated solution, is it more good to use microphone such as MP23AB01DH?

    ST microphones don't have a wake up embedded feature (like for example piezo microphones). In LP mode, an analog mic I supply is about 80-100uA, while for a digital mic is around 350uA.

    -Eleon

    1 reply

    E
    Eleon BORLINIAnswer
    ST Employee
    September 9, 2022

    Hi @SSong.2​ ,

    #01.

    Is it possible to generate interrupt from deep sleep when vibration detected by iis2dh?

    As described in the datasheet p.18, you can set peak and duration of the signal waking up the device. You might tune the peake and the duration according to the fundamental frequency of your vibration, if not too high (duration is proportional to the selected ODR).

    The IIS2DH can be programmed to automatically switch to low-power mode upon recognition of a determined event. Once the event condition is over, the device returns back to the preset normal or high resolution mode. To enable this function the desired threshold value must be stored inside the Act_THS (3Eh) register while the duration value is written inside the Act_DUR (3Fh) register. When the acceleration falls below the threshold value, the device automatically switches to low-power mode (10Hz ODR). During this condition, the ODR[3:0] bits and the LPen bit inside CTRL_REG1 (20h) and the HR bit in CTRL_REG3 (22h) are not considered. As soon as the acceleration rises above threshold, the module restores the operating mode and ODRs as determined by the CTRL_REG1 (20h) and CTRL_REG3 (22h) settings.

    #02.

    for more sophisticated solution, is it more good to use microphone such as MP23AB01DH?

    ST microphones don't have a wake up embedded feature (like for example piezo microphones). In LP mode, an analog mic I supply is about 80-100uA, while for a digital mic is around 350uA.

    -Eleon

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