Vibration Monitoring using LIS3DH sensor on nRF52840

[Anmol Maske]

Hi Nordic team,

I hope this message finds you well. I am currently working on developing applications for custom boards utilizing the nRF Connect SDK v2.4.0, with a particular focus on the nRF52840 microcontroller.

In our ongoing project, we have a requirement to implement a feature involving Vibration Monitoring, which triggers whenever a threshold level is crossed. I have successfully interfaced the sensor and am able to obtain X, Y, and Z values using the LIS2DH drivers. However, I am encountering difficulties in implementing the vibration detection using the interrupt pin. Although I have specified the interrupt pin in the .overlay file, I am not receiving the expected output.

&i2c0 {
    lis2dh@19 {
        compatible = "st,lis2dh";
        reg = <0x19>;
		status = "okay";		
        label = "LIS3DH";
		irq-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>, <&gpio0 1 GPIO_ACTIVE_HIGH>;
		disconnect-sdo-sa0-pull-up;
    };
};

Could you please provide some sample code for reference regarding Vibration Monitoring?

Additionally, I would like to inquire if LIS3DH drivers are available, as it would be beneficial for our project.

Best regards,

Anmol

[Hakon]

Hello,

Although I have specified the interrupt pin in the .overlay file, I am not receiving the expected output.

can you please provide more information about the problem? Maybe some logs and such.

[Anmol Maske]

Hello Hakon,

I'm using LIS3DH sensor and having trouble understanding how to utilize interrupts that trigger whenever a vibration threshold level, for example, 5m/s^2, is exceeded. Could you please provide some sample code for reference regarding Vibration Monitoring?

Regards,

Anmol

[Hakon]

Anmol Maske said:

Could you please provide some sample code for reference regarding Vibration Monitoring?

I think the best example would be the asset tracker v2, but it's not quite for vibration monitoring. You can still look at the accelerometer configuration to check how it's done.

[Anmol Maske]

Hi,

I have solved the problem. Directly used the interrupt trigger function from lis2dh sample and threshold attribute in sensor_attr_set() function with some manual computations. This is giving me readings whenever threshold level is crossed.

/*Enable trigger handler for LIS*/
static void lis_trigger_handler(const struct device *dev, const struct sensor_trigger *trigger)
{
	int64_t uptime = k_uptime_get();
    
    if(uptime >= 750){

		LOG_INF("Vibration is beyond the 750ms\n");
		vibration_detected = 1;
		read_sound();

	}
	else
	{
		vibration_detected = 0;
	}

}

/*Threshold for Vibration Monitering*/
void configure_lis_vibration_threshold(const struct device *lis_dev) {

    int ret;
    struct sensor_value vib_val;
	
    vib_val.val1 = lowG_vib_threshold; // Adjust this threshold value as needed
    vib_val.val2 = 0; //(int32_t) SENSOR_G *1.5
   
       struct sensor_trigger lis_trig = {
        .type = SENSOR_TRIG_DATA_READY,
        .chan = SENSOR_CHAN_ACCEL_XYZ,
    };
    
    // Set sensor attribute for upper threshold
    ret=	sensor_attr_set(lis_dev, SENSOR_CHAN_ACCEL_X, SENSOR_ATTR_UPPER_THRESH,&vib_val);
    if (ret) {
        LOG_ERR("Failed to set sensor attribute: %d", ret);
        return;
    }
	
    // Register trigger handler
    ret = sensor_trigger_set(lis_dev, &lis_trig, lis_trigger_handler);
    if (ret) {
        LOG_ERR("Failed to set sensor trigger: %d", ret);
        return;
    }
}

/*Read Sound Values with/without Vibration*/
void read_sound(){
    
	configure_lis_vibration_threshold(lis2dux12);
    wakeup_now();

	LOG_INF("Sound reading is started");
	LOG_INF("Vibration detected flag = %d", vibration_detected);
	if(vibration_detected) 
	{
		Motion_Started = 1;
		// Add sleep mode
		k_sleep(K_MSEC((1000 * motion_sound_rate) - 1000));  
		vibration_detected = 0;
	}
	else
	{
		Motion_Started = 0;
	}

	sleep_now();
}