NUCLEO-L432KC accelerometer example

nucleo_l432kc_accelerometer_buzzer.cpp

#include "mbed.h"
#include "LIS3DH.h"
#include <math.h>

#define USE_LED
#define USE_SERIAL

#ifdef USE_SERIAL
Serial pc(SERIAL_TX, SERIAL_RX);
#endif

#ifdef USE_LED
DigitalOut myled(LED1);
#endif

DigitalOut buzzer(PB_4);
const uint8_t CHIP_ADDRESS = 0x30; // Pulled-down by Jumper C
// LIS3DH accelerometer(I2C_SDA, I2C_SCL, SA0);
LIS3DH accelerometer(PB_7, PB_6, CHIP_ADDRESS);
const char* AXIS_LABEL[] = { "X", "Y", "Z" };
const float GRAVITY_VECTOR[] = {0, 0, 1};
const float RAD_TO_DEG = 360.0/(2*3.1415926535);
const float OFF_ANGLE_THRESHOLD_DEG = 80;
const uint8_t WAIT_DURATION_SEC = 1;

float magnitude(const float* vec)
{
    return sqrt(vec[0]*vec[0] + vec[1]*vec[1] + vec[2]*vec[2]);
}

float inner_product(const float* vec_a, const float* vec_b)
{
    return vec_a[0]*vec_b[0] + vec_a[1]*vec_b[1] + vec_a[2]*vec_b[2];
}

float off_angle_deg(const float* vec_a, const float* vec_b)
{
    float cos_theta = inner_product(vec_a, vec_b) / (magnitude(vec_a) * magnitude(vec_b));
    float theta_rad = acos(cos_theta);
    return theta_rad * RAD_TO_DEG;
}

void pulse_buzzer()
{
    for(size_t i=0; i<10; i++) {
        buzzer = 1;
        wait(0.05);
        buzzer = 0;
        wait(0.05);
    }
}

void set_buzzer(float off_angle)
{
    if ( off_angle > OFF_ANGLE_THRESHOLD_DEG) {
        pulse_buzzer();
    } else {
        buzzer = 0;
    }
}

int main()
{
    pulse_buzzer();
    float acc[3];
    uint32_t id = 0;
    uint32_t ready = 0;
    float off_angle = 0;

    id = accelerometer.read_id();
#ifdef USE_SERIAL
    pc.printf("LIS3DH ID = 0x%02x\n", id);
#endif

    while(true) {
        wait(WAIT_DURATION_SEC);
        ready = accelerometer.data_ready();
        accelerometer.read_data(acc);
        off_angle = off_angle_deg(acc, GRAVITY_VECTOR);
        set_buzzer(off_angle);
#ifdef USE_SERIAL
        pc.printf("LIS3DH Ready = %d\n", ready);
        for(size_t i=0; i < 3; i++) {
            pc.printf("%s = %.4f\n", AXIS_LABEL[i], acc[i]);
        }
        pc.printf("Off angle %.1f deg\n", off_angle);
#endif

#ifdef USE_LED
        myled = !myled;
#endif
    }
}