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How To: PIR Module

The PIR module is mostly used as a motion detector. Thanks to its low power consumption it can safely be used with batteries acting as the only power source.

References​

Sensitivity​

SDK offers you four types of sensitivity defined as enum type, so you can use simple names:

  • TWR_MODULE_PIR_SENSITIVITY_LOW
  • TWR_MODULE_PIR_SENSITIVITY_MEDIUM
  • TWR_MODULE_PIR_SENSITIVITY_HIGH
  • TWR_MODULE_PIR_SENSITIVITY_VERY_HIGH

It is very hard to predict how exactly the PIR sensor will act in your particular use case, it is always a good idea to test every type of sensitivity to find out which one to use for the best results.

Example​

info

This example uses Medium sensitivity. When movement is detected, the message Movement! is sent to your computer via USB.

Motion Detection Code Example

#include <application.h>

twr_module_pir_t pir;
twr_button_t button;

void pir_event_handler(twr_module_pir_t *self, twr_module_pir_event_t event, void *event_param)
{
    (void) self;
    (void) event_param;

    if (event == TWR_MODULE_PIR_EVENT_MOTION)
    {
        twr_log_debug("Movement detected!");
    }
}

void application_init(void)
{
    twr_log_init(TWR_LOG_LEVEL_DEBUG, TWR_LOG_TIMESTAMP_ABS);

    twr_module_pir_init(&pir);
    twr_module_pir_set_sensitivity(&pir, TWR_MODULE_PIR_SENSITIVITY_MEDIUM);
    twr_module_pir_set_event_handler(&pir, pir_event_handler, NULL);
}