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Interrupt_settings.md

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Steps to configure BMM150 Interrupts

  1. Set the value of "desired_settings" from the list of macros from TABLE 1.0-Macros for enabling the desired_settings to enable the configuration of the selected settings. (Multiple settings can be set by bitwise OR-ing of the macros)

    Ex. desired_settings = BMM150_SEL_DRDY_PIN_EN | BMM150_SEL_DRDY_POLARITY;

  2. Set the desired configuration in the dev structure using macros from the TABLE 1.1-Interrupt configuration settings.

    NOTE : Configuration settings will be set only when we set the corresponding "desired_settings" which enables the settings.

	/* Select the DRDY pin and polarity settings */
	desired_settings = BMM150_SEL_DRDY_PIN_EN | BMM150_SEL_DRDY_POLARITY;
	/* Set the desired configurations of DRDY pin and its polarity */
  	dev->settings.int_settings.drdy_pin_en = BMM150_INT_ENABLE;
	dev->settings.int_settings.drdy_polarity = BMM150_ACTIVE_LOW_POLARITY;

  1. Invoke the "bmm150_set_sensor_settings" API after setting the desired configuration in dev structure and enabling the corresponding "desired_settings" value,

  2. Invoke the "bmm150_get_interrupt_status" API to get the interrupt status value in the dev->int_status.

    The value of dev->int_status is taken and a bitwise AND operation is performed with predefined interrupt status macros (listed below) to find the interrupt status which is either set or reset.

    • BMM150_INT_THRESHOLD_X_LOW
    • BMM150_INT_THRESHOLD_Y_LOW
    • BMM150_INT_THRESHOLD_Z_LOW
    • BMM150_INT_THRESHOLD_X_HIGH
    • BMM150_INT_THRESHOLD_Y_HIGH
    • BMM150_INT_THRESHOLD_Z_HIGH
    • BMM150_INT_DATA_OVERFLOW
    • BMM150_INT_DATA_OVERRUN
    • BMM150_INT_DATA_READY
 /* Example for checking interrupt status*/
 if (dev->int_status & BMM150_INT_ASSERTED_DRDY) {
 	/*Occurrence of data ready interrupt */
	printf("\n Interrupt asserted");
 } else {
 	/* No interrupt occurred */
	printf("\n Interrupt not asserted");
 }

NOTE : The interrupt configuration settings which are set can be read from the sensor by invoking the "bmm150_get_sensor_settings" API.

NOTE : In BMM150 the interrupt pin INT is in default latched state and the polarity of INT and DRDY pins in default is active high.

NOTE : The macros mentioned below are present in the bmm150_defs.h file for setting the desired user configuration.

TABLE 1.0-Macros for enabling the desired_settings

Macros to set for "desired_settings" Settings which can be enabled/Disabled
BMM150_SEL_DRDY_PIN_EN Data ready interrupt mapping to DRDY PIN
BMM150_SEL_INT_PIN_EN Low-Threshold, High-Threshold and Overflow interrupts mapping to INT PIN
BMM150_SEL_DRDY_POLARITY Polarity of DRDY pin
BMM150_SEL_INT_LATCH Latch settings of INT pin
BMM150_SEL_INT_POLARITY Polarity of INT pin
BMM150_SEL_DATA_OVERRUN_INT Data overrun interrupt setting
BMM150_SEL_OVERFLOW_INT Data overflow interrupt setting
BMM150_SEL_HIGH_THRESHOLD_INT High threshold interrupt setting
BMM150_SEL_LOW_THRESHOLD_INT Low threshold interrupt setting
BMM150_SEL_LOW_THRESHOLD_SETTING Setting Low threshold value to trigger interrupt
BMM150_SEL_HIGH_THRESHOLD_SETTING Setting High threshold value to trigger interrupt

TABLE 1.1-Interrupt configuation settings

User configration in the dev structure Macros which can be assigned Significance
dev->settings.int_settings.drdy_pin_en BMM150_INT_ENABLE Maps the data ready interrupt to the DRDY pin of sensor
^ BMM150_INT_DISABLE Disables the mapping of data ready interrupt signal to the DRDY pin
dev->settings.int_settings.int_pin_en BMM150_INT_ENABLE Enables the mapping of Low-Threshold, High-Threshold and Overflow interrupts to INT (interrupt) pin
^ BMM150_INT_DISABLE Disables the interrupt mapping to the INT pin
dev->settings.int_settings.drdy_polarity BMM150_ACTIVE_HIGH_POLARITY Sets the interrupt signal polarity in DRDY pin as active high
^ BMM150_ACTIVE_LOW_POLARITY Sets the interrupt signal polarity in DRDY pin as active low
dev->settings.int_settings.int_polarity BMM150_ACTIVE_HIGH_POLARITY Sets the interrupt signal polarity in INT pin as active high
^ BMM150_ACTIVE_LOW_POLARITY Sets the interrupt signal polarity in INT pin as active low
dev->settings.int_settings.int_latch BMM150_LATCHED Sets the interrupt signal in INT pin in latched mode
^ BMM150_NON_LATCHED Sets the interrupt signal in INT pin in non - latched mode
dev->settings.int_settings.data_overrun_en BMM150_INT_ENABLE Enables the data overrun interrupt
^ BMM150_INT_DISABLE Disables the data overrun interrupt
dev->settings.int_settings.overflow_int_en BMM150_INT_ENABLE Enables the overflow interrupt
^ BMM150_INT_DISABLE Disables the overflow interrupt
dev->settings.int_settings.high_int_en BMM150_THRESHOLD_X Enables the threshold interrupt detection for X axis
dev->settings.int_settings.high_int_en BMM150_THRESHOLD_Y Enables the threshold interrupt detection for Y axis
^ BMM150_THRESHOLD_Z Enables the threshold interrupt detection for Z axis
^ (BMM150_THRESHOLD_X & BMM150_THRESHOLD_Y) Enables the threshold interrupt detection for x,y axes
^ (BMM150_THRESHOLD_X & BMM150_THRESHOLD_Y & BMM150_THRESHOLD_Z) Enables the threshold interrupt interrupt detection for all 3 X,Y and Z axes

Configuring and handling BMM150 Interrupts

Example for using high threshold interrupt

Configuring the high threshold interrupt

int8_t high_threshold_interrupt(struct bmm150_dev *dev)
{
	int8_t rslt;
	uint16_t desired_settings;

	/* Enable the desired settings to be set in the sensor */
	desired_settings = BMM150_SEL_HIGH_THRESHOLD_INT | BMM150_SEL_HIGH_THRESHOLD_SETTING |
		BMM150_SEL_INT_PIN_EN | BMM150_SEL_INT_POLARITY | BMM150_SEL_INT_LATCH;
	
	/* Set the desired configuration */
	/* Enable the mapping of interrupt to the interrupt pin*/
	dev->settings.int_settings.int_pin_en = BMM150_INT_ENABLE;
	/* Set the interrupt in non latched mode */
	dev->settings.int_settings.int_latch = BMM150_NON_LATCHED;
	/* Set the interrupt polarity as active high */
	dev->settings.int_settings.int_polarity = BMM150_ACTIVE_HIGH_POLARITY;
	/* Set the threshold value as 0x0A (10*6 = 60 micro-tesla)*/
	dev->settings.int_settings.high_threshold = 0x0A;
	/* Set the high threshold detection for all 3 axis */
	dev->settings.int_settings.high_int_en = BMM150_THRESHOLD_X & BMM150_THRESHOLD_Y & BMM150_THRESHOLD_Z;
	
	/* Set the configurations in the sensor */
	rslt = bmm150_set_sensor_settings(desired_settings, dev);
	
	return rslt;
}

Read the interrupt status continuously to check for interrupt assertion (Polling method)

int8_t high_threshold_interrupt_handling(struct bmm150_dev *dev)
{
	int8_t rslt;
	
	rslt = bmm150_get_interrupt_status(dev);
	if (rslt == BMM150_OK) {
		if (dev->int_status & BMM150_INT_THRESHOLD_X_HIGH) {
			printf("\n HIGH THRESHOLD INTERRUPT ON X AXIS ");
		}
		if (dev->int_status & BMM150_INT_THRESHOLD_Y_HIGH) {
			printf("\n HIGH THRESHOLD INTERRUPT ON Y AXIS ");
		}
		if(dev->int_status & BMM150_INT_THRESHOLD_Z_HIGH) {
			printf("\n HIGH THRESHOLD INTERRUPT IN Z AXIS ");
		}
	}
	
	return rslt;
}

Example for using multiple interrupts (data ready and overflow interrupts)

Configuring the overflow and data ready interrupts and interrupt pins and latch settings

int8_t drdy_overflow_int_setting(struct bmm150_dev *dev)
{
	int8_t rslt;
	uint16_t desired_settings;

	/* Enable the desired settings to be set in the sensor */
	desired_settings = BMM150_SEL_DRDY_PIN_EN | BMM150_SEL_OVERFLOW_INT |
		BMM150_SEL_INT_PIN_EN | BMM150_SEL_INT_LATCH;
	
	/* Set the desired configuration */
	/* Enable the drdy interrupt  */
	dev->settings.int_settings.drdy_pin_en = BMM150_INT_ENABLE;
	/* Enable the mapping of interrupt to the interrupt pin */
	dev->settings.int_settings.int_pin_en = BMM150_INT_ENABLE;
	/* Enable the overflow interrupt */
	dev->settings.int_settings.overflow_int_en = BMM150_INT_ENABLE;
	/* Set the interrupt in non latched mode */
	dev->settings.int_settings.int_latch = BMM150_NON_LATCHED;

	/* Set the configurations in the sensor */
	rslt = bmm150_set_sensor_settings(desired_settings, dev);
	
}

Read the interrupt status continuously to check for interrupt assertion (Polling method)

int8_t drdy_overflow_int_handling(struct bmm150_dev *dev)
{
	int8_t rslt;

	rslt = bmm150_get_interrupt_status(dev);
	if (rslt == BMM150_OK) {
		/* Multiple interrupt assertion can be checked as follows */
		if ((dev->int_status & BMM150_INT_ASSERTED_DRDY) ||
			(dev->int_status & BMM150_INT_DATA_OVERFLOW)) {
			/* Either data ready or overflow has occurred */
			printf("\n Interrupt asserted ");
		} else {
			printf("\n Interrupt not asserted ");
		}
	}
	
	return rslt;
}