Earthquake click

Earthquake click carries D7S, the world’s smallest high-precision seismic sensor from Omron. The click is designed to run on either 3.3V or 5V power supply. It communicates with the target MCU over I2C interface, with additional functionality provided by the following pins on the mikroBUS™ line: PWM, INT, CS.

When an earthquake occurs with a seismic intensity equivalent to 5 Upper or higher on the JMA (Japan Meteorological Agency) Seismic Intensity Scale, the D7S will activate the shutoff output to notify the user that an earthquake has occurred.

How it works

Using the SI (spectral intensity) value, which has a high correlation with the seismic intensity scale that indicates the magnitude of an earthquake, provides higher-precision judgment of seismic intensity scales.

The 3-axis acceleration Sensor and Omron's unique SI value calculation algorithm achieve high precision and low consumption. (Higher degree of freedom for incorporation into devices and prolonged operation on battery power).

Shutoff output terminal (INT1) operates equivalent to a conventional mechanical vibration sensor and ensures compatibility with mechanical vibration sensors.

I2C interface is able to obtain earthquake-related information from the sensor with communications from external devices.

Spectral intensity

The SI value (or spectral intensity) is equivalent to the magnitude of the destructive energy imposed by seismic motion on structures.

Low power consumption

The power consumption during standby is 90 μA or less. On average, during processing, the sensor uses around 300 μA.

JMA seismic intensity scale

JMA or Japan Meteorological Agency intensity scale is used in Japan and Taiwan to measure the intensity of earthquakes. The scale goes from 0 to 7. The level 5 on this scale indicates when objects inside a house start falling down, like books from the shelf, dishes in a cupboard, cracks are formed on walls, etc.

Specifications

Pinout diagram

This table shows how the pinout on Earthquake click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	INT2	Processing notification output
	NC	2	RST	INT	15	INT1	Shutoff output
Initial setting input	SETTING	3	CS	TX	14	NC
	NC	4	SCK	RX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C clock
	NC	6	MOSI	SDA	11	SDA	I2C data
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

Maximum ratings

Jumpers and settings

Programming

Code examples for Earthquake click, written for MikroElektronika hardware and compilers are available on Libstock.

Code snippet

The following code calls initialization functions, and then checks the status and SI value registers every 5 seconds.

01 void main(){
02
03   system_init ();
04   eq_init(0x55);
05
06   while (1)
07   {
08       UART_Write_Text( "rn Status: " );
09       si_value = eq_read_status ();
10       IntToStr( si_value, uart_text );
11       UART_Write_Text(uart_text);
12       UART_Write( 32 );
13
14       /*reads strongest SI value detected during current quake */
15       UART_Write_Text( " Current SI value: " );
16       si_value = eq_si_rs ();
17       IntToStr( si_value, uart_text );
18       UART_Write_Text(uart_text);
19       UART_Write( 32 );
20
21       Delay_ms (5000);
22 }
23 }