Viviana Staicu

What I wanted to learn, and why it interested me:

I've been curious about these use cases for a while:

- detect if a device rightside up or upsidown

- detect how / if someone is flipping a device.

- detect if someone is tapping a table or a hard surface nearby the device.

“Registered tap” of sorts.

This is because last semester, I worked on a conceptual device that detected your presence and made it aware to people in other rooms via a little totem that you'd flip upsidown to 'clock out' per say. It was never fully realized with electronics.

LEFT: Final Video with caption annotations. 

RIGHT: Screencap of me using the potentiometer to ater the step registration threshold (pink line).

Process and reflection: 

First, I started out by just trying to observe the behavior and sensitivity of my accelerometer.

It turned out that I had to whack it super hard in one axes until it registered as a 'step'.

I discovered that this was for two reasons:

1. I had a delay of 500ms. When you do such a long delay in your loop, arduino is only checking if a hit surpasessed the threshold every 500ms! Thats very slow frequency of checking if someone whacked the accelerometer. I removed the delay, and the issue was almost resolved.

2. I had to lower the threshold a bit to register a hit. 500 was too high, 430 was just right, and 420 meant no movement.

Then I hooked up the potentiometer to control the threshold level that registered a hit, and made a little counter for it. 

I'm satisfied with where I ended up. I think it would've been cool to visualize the serial plotter on an oled though- its really satisfying to watch the visualization!

/*

    60-223 Intro to Physical Computing, fall 2025

    Domain-specific Skill Building exercise: [Viviana's pedometer.]

    Potentiometer controls a threshold. 

The user should hit (hard tap on the top) the accelerometer holding it vertically on the Y axis.

            If the Y value of the accelerometer surpasses the value set by the potentiometer, a 'step' is registered.

The the number of steps is counted and printed to the serial monitor. See the serial plotter for a more logical visualization.

    Pin mapping:

    Arduino pin | role  | details

    ------------------------------

    A0             input   potentiometer

    A1             input   X axis > accelerometer

A2   input   Y axis > accelerometer

A4   input   Z axis > accelerometer

    Released to the public domain by the author, January 2024

    Robert Zacharias, rzachari@andrew.cmu.edu

*/

/*

* This program reads an accelerometer connected to ACCEL_X_PIN,

* ACCEL_Y_PIN, and ACCEL_Z_PIN and sends the data back to the

* computer via serial.

*

* Branched off of the example for the accelerometer on ioref site by Perry Naseck

*/

const int ACCEL_X_PIN = A1; // Analog input pin for X movement

const int ACCEL_Y_PIN = A2; // Analog input pin for Y movement

const int ACCEL_Z_PIN = A4; // Analog input pin for Z movement

const int POT_PIN = A0; // Analog input pin for the potentiometer

// Variables to keep track of the current positions

int accelXPos = 0;

int accelYPos = 0;

int accelZPos = 0;

int potThresh = 0;

int stepCount = 0;

bool wasStepping = false;

// Potentiometer setting threshold for step detection

// int readHighRes(int A2) {

//   long sum = 0;

//   for (int i = 0; i < 16; i++) {

//     sum += analogRead(A2);

//   }

//   return sum / 16;

// }

void setup() {

 // Setup serial port to send the accelerometer data back to the computer

 Serial.begin(9600);

 // Setup the accelerometer inputs

 pinMode(ACCEL_X_PIN, INPUT);

 pinMode(ACCEL_Y_PIN, INPUT);

 pinMode(ACCEL_Z_PIN, INPUT);

}

void loop() {

 // Get the current states

 accelXPos = analogRead(ACCEL_X_PIN);

 accelYPos = analogRead(ACCEL_Y_PIN);

 // accelYPos = readHighRes(ACCEL_Y_PIN);

 accelZPos = analogRead(ACCEL_Z_PIN);

  potThresh = analogRead(POT_PIN);

 // Send the data in Serial Plotter format (Label:Value separated by tabs)

 Serial.print("X:");

 Serial.print(accelXPos);

 Serial.print("\t");

 Serial.print("Y:");

 Serial.print(accelYPos);

 Serial.print("\t");

 Serial.print("Z:");

 Serial.print(accelZPos);

 Serial.print("\t");

 Serial.print("P:");

 Serial.print(potThresh);

 Serial.print("\t");

 // Step detection: count on rising edge (transition from not stepping to stepping)

 if (potThresh <= accelYPos) {

   if (!wasStepping) {

     stepCount++;

     wasStepping = true;

   }

   Serial.print("STEPPED");

 } else {

   wasStepping = false;

   Serial.print("No step");

 }

 Serial.print("\tSteps:");

 Serial.println(stepCount);

 // delay(1);

}