Serial monitor doesn't show anything

Using Arduino Programming Questions
1

Hi there, this is regarding a fall detection. I have attached the code. It doesn't seem to print anything in the serial monitor. This is my first time doing this, and I can't find the error.

#include <Wire.h>         // I2C communication
#include <BMA250.h>       // Accelerometer library

// Accelerometer variables
BMA250 accel_sensor;
int x, y, z;
double temp;
float accelMagnitude;

// Fall detection thresholds
float impactThreshold = 2.5;
float freeFallThreshold = 0.5;
float recoveryThreshold = 1.0;
unsigned long recoveryDelay = 1000;

// Fall detection states
enum FallState { IDLE, IMPACT_DETECTED, FREE_FALL_DETECTED };
FallState fallState = IDLE;

unsigned long impactTime = 0;
unsigned long freeFallTime = 0;

// Setup Serial for different boards
#if defined(ARDUINO_ARCH_SAMD)
 #define SerialMonitorInterface SerialUSB
#else
 #define SerialMonitorInterface Serial
#endif

void setup() {
    SerialMonitorInterface.begin(115200);
    Wire.begin();

    SerialMonitorInterface.println("Initializing BMA250...");
    if (!accel_sensor.begin(BMA250_range_2g, BMA250_update_time_64ms)) {
        SerialMonitorInterface.println("ERROR: BMA250 not detected!");
        while (1);
    }
    SerialMonitorInterface.println("BMA250 initialized successfully.");
}

void loop() {
    accel_sensor.read();  // Read accelerometer data
    x = accel_sensor.X;
    y = accel_sensor.Y;
    z = accel_sensor.Z;

    temp = ((accel_sensor.rawTemp * 0.5) + 24.0);

    if (x == -1 && y == -1 && z == -1) {
        SerialMonitorInterface.println("ERROR: Invalid data.");
        return;
    }

    accelMagnitude = sqrt(sq(x) + sq(y) + sq(z));  // Calculate magnitude

    switch (fallState) {
        case IDLE:
            if (accelMagnitude > impactThreshold) {
                SerialMonitorInterface.println("Impact detected!");
                impactTime = millis();
                fallState = IMPACT_DETECTED;
            }
            break;

        case IMPACT_DETECTED:
            if (accelMagnitude < freeFallThreshold) {
                SerialMonitorInterface.println("Free fall detected!");
                freeFallTime = millis();
                fallState = FREE_FALL_DETECTED;
            } else if (millis() - impactTime > recoveryDelay) {
                SerialMonitorInterface.println("False alarm, resetting to IDLE.");
                fallState = IDLE;
            }
            break;

        case FREE_FALL_DETECTED:
            if (accelMagnitude < recoveryThreshold && (millis() - freeFallTime) > 500) {
                SerialMonitorInterface.println("Fall confirmed!");
                fallState = IDLE;
            } else if (millis() - freeFallTime > recoveryDelay) {
                SerialMonitorInterface.println("False alarm, resetting to IDLE.");
                fallState = IDLE;
            }
            break;
    }

    showSerial();  // Debugging output
    delay(250);    // Adjust delay as necessary
}

void showSerial() {
    SerialMonitorInterface.print("X = ");
    SerialMonitorInterface.print(x);
    SerialMonitorInterface.print("  Y = ");
    SerialMonitorInterface.print(y);
    SerialMonitorInterface.print("  Z = ");
    SerialMonitorInterface.print(z);
    SerialMonitorInterface.print("  Temp (C) = ");
    SerialMonitorInterface.print(temp);
    SerialMonitorInterface.print("  Accel Magnitude = ");
    SerialMonitorInterface.println(accelMagnitude);
}
2

Serial monitor needs to be set to 115200, same value as is used in the begin() statement

3

serial monitor is set to 115200 also. doesn't print anything.

4

Instead of using "SerialMonitorInterface", try "Serial" (e.g. Serial.begin(115200), Serial.println).

5

Hi @Bruce123,

welcome to the arduino-forum.
Well done posting your code as a code-section in your very first posting.

You should add more information.
You did not include what exact BMA250-library you are using.
The library-manager doesn't find one
and on GitHub there are more than one BMA250-libraries.

What exact type of microcontroller-board are you using?

For almost all microcontroller-boards using "Serial" as the name for the serial interface will work

Additionally you should add a line of code that prints to the serial monitor
right below Serial.begin(115200);

unconditional so the printing is done always independant of any conditions
So the modificated code looks like this

#include <Wire.h>         // I2C communication
#include <BMA250.h>       // Accelerometer library

// Accelerometer variables
BMA250 accel_sensor;
int x, y, z;
double temp;
float accelMagnitude;

// Fall detection thresholds
float impactThreshold = 2.5;
float freeFallThreshold = 0.5;
float recoveryThreshold = 1.0;
unsigned long recoveryDelay = 1000;

// Fall detection states
enum FallState { IDLE, IMPACT_DETECTED, FREE_FALL_DETECTED };
FallState fallState = IDLE;

unsigned long impactTime = 0;
unsigned long freeFallTime = 0;


void setup() {
    Serial.begin(115200);
    delay(2000); // wait to seconds in case intialising Serial takes some time
    Serial.println("Setup-Start");
    Wire.begin();

    Serial.println("Initializing BMA250...");
    if (!accel_sensor.begin(BMA250_range_2g, BMA250_update_time_64ms)) {
        Serial.println("ERROR: BMA250 not detected!");
        while (1);
    }
    Serial.println("BMA250 initialized successfully.");
}

void loop() {
    accel_sensor.read();  // Read accelerometer data
    x = accel_sensor.X;
    y = accel_sensor.Y;
    z = accel_sensor.Z;

    temp = ((accel_sensor.rawTemp * 0.5) + 24.0);

    if (x == -1 && y == -1 && z == -1) {
        Serial.println("ERROR: Invalid data.");
        return;
    }

    accelMagnitude = sqrt(sq(x) + sq(y) + sq(z));  // Calculate magnitude

    switch (fallState) {
        case IDLE:
            if (accelMagnitude > impactThreshold) {
                Serial.println("Impact detected!");
                impactTime = millis();
                fallState = IMPACT_DETECTED;
            }
            break;

        case IMPACT_DETECTED:
            if (accelMagnitude < freeFallThreshold) {
                Serial.println("Free fall detected!");
                freeFallTime = millis();
                fallState = FREE_FALL_DETECTED;
            } else if (millis() - impactTime > recoveryDelay) {
                Serial.println("False alarm, resetting to IDLE.");
                fallState = IDLE;
            }
            break;

        case FREE_FALL_DETECTED:
            if (accelMagnitude < recoveryThreshold && (millis() - freeFallTime) > 500) {
                Serial.println("Fall confirmed!");
                fallState = IDLE;
            } else if (millis() - freeFallTime > recoveryDelay) {
                Serial.println("False alarm, resetting to IDLE.");
                fallState = IDLE;
            }
            break;
    }

    showSerial();  // Debugging output
    delay(250);    // Adjust delay as necessary
}

void showSerial() {
    Serial.print("X = ");
    Serial.print(x);
    Serial.print("  Y = ");
    Serial.print(y);
    Serial.print("  Z = ");
    Serial.print(z);
    Serial.print("  Temp (C) = ");
    Serial.print(temp);
    Serial.print("  Accel Magnitude = ");
    Serial.println(accelMagnitude);
}

I could not compile this code because it is unclear which BMA250-library you are using

6 
if (!accel_sensor.begin(BMA250_range_2g, BMA250_update_time_64ms)) {
        SerialMonitorInterface.println("ERROR: BMA250 not detected!");
        while (1);

i got it working. this loop is the one with problem. not sure what is problem. but I took away the loop. now can print.

accel_sensor.begin(BMA250_range_2g, BMA250_update_time_64ms

Background information:
BMA250: TinyCircuits-BMA250-library
I'm using TinyZero Processor Board

Thanks for the help guys