What is the best configuration for saving current consumption when making IOT sensor nodes with lis3dh sensors?

[JJu.1884]

We made a very simple becon sensor.

It would take about 25 micro amps to be a pure becon without the vibration sensor.

In a vibration free environment, it takes 35 microamps to measure vibration using the lis3dh sensor.

It is the ideal current consumption that we want.

However, if it is attached to an air conditioner in a place with vibration, it consumes current up to 112 micro amps.

Please let me know if there is a way to use 35 to 45 microamps where there is vibration.

For reference, the accuracy of the magnitude of vibration is not important and only a rough measurement is required.

[Eleon BORLINI]

Hi @JJu.1884​ , let me check if I have well understood: in your beacon application you want to acquire data, I mean, have a master SPI or I2C and a slave, the lis3dh sensor, and save the data somewhere, right? In this case, you must have a microcontroller (e.g. STM32) onboard and your power consumption requirements are very thigh... However, I suggest you to consider the current consumption estimator of the STM32CubeIDE, that enables you to define the right processor for minimizing the current consumption of the system. For example, if you select a low power MCU such as STM32L4, working at 16MHz, internal oscillator (not recommended) and with a single SPI enabled, you will get a current consumption below 50uA. You could do better if the MCU stays in sleeping mode for almost all the time and turned on with SPI running for the rest of the time.

However, if you need only to detect and manage a single inertial event (for example, the vibration exceeds a threshold, the sensor generates an interrupt and this triggers another event), you can set-up your beacon with the only lis3dh sensor onboard, powering it with a low power battery and programming it from external connector. You have to set-up the device memory ad described in AN3308 p.22 (Inertial wake-up example).

Regards