DIY Activity Tracker

The DIY Activity Tracker is they are connected with mobile devices by Bluetooth and track the daily routine of users. The Activity Tracker records the number of steps and calories lost using an Arduino Pro Mini.


Akash H.

Area of Interest

Electrical Engineering


Cupertino High School


Incoming Junior

Demo Night

Watches are getting more and more advanced everyday. I was able to experience a small part of this process by building a watch that records the amount of steps taken and the calories burned. After six weeks of toiling on my project I finally finished and had a working model. I am really proud of all the obstacles I have overcome and having a project that I made all by myself instead of buying it from a store. In the future I hope to make my project more compact as it is barely fits on my hand and would be really difficult to walk with it.

Third Milestone

DIY Activity Tracker

The build process and the programming went pretty smoothly while working on this milestone. While assembling the project I didn’t have any problems as all I had to do was solder on some header pins to the Arduino Pro Mini and connect all my components via jumper cables. After I connected all my components together and already flashed my program onto the Arduino my problem started. I tested the project with the app but it wouldn’t display any of the accelerometer data. I ran through all of my code and there was no problem in it. I then checked up the problem and thought that a pull-up resistor should solve the issue with the Arduino. I tried implementing that solution and realized that the problem was I had connected the SDA and SCL pins to the wrong one. While working on this milestone I learned many different programming aspects and how they work specific to my code along with what pull-up and pull-down resistors are. A pull-up resistor or pull-down resistor is a resistor used to ensure a known state for a signal and usually used in components such as transistors and switches. 

I reached my third milestone for my main project, which was making sure the accelerometer and Bluetooth module work smoothly with the Arduino Pro Mini and app. My project now can transmit and receive data to and from an app using the accelerometer and Bluetooth module. The allows the user to receive data from their phone about the number of the steps they took and while wearing the band and calories burnt.

Second Milestone

DIY Activity Tracker

The building process was pretty simple as I only had to connect a few wires to an Arduino Uno. While establishing the connections I didn’t have any roadblocks. After I had finished with the wired connections from the module to the board I ran into many problems. The instructions had mentioned that once the module is paired with a device the light should stop blinking and the module wouldn’t do that. After troubleshooting this problem I figured that the module needs to be paired with an app to stop blinking and carry out a function. Something I learned while working on this milestone is how the Bluetooth module works. The Bluetooth module is a slave module and is designed for wireless serial communication. A slave module meaning that it can receive serial data when serial data is sent out from a device able to send serial data through the air such as smartphones. This allows for the Arduino to be controlled via a master device. 

I reached my second milestone for my main project, which was making sure my Bluetooth module works with an Arduino Uno. The Bluetooth module allows for the Arduino to connect to any Android device that supports it. This allows for the user to execute functions without wires.

DIY Activity Tracker

First Milestone – DIY Activity Tracker

DIY Activity Tracker

There wasn’t much to the build process as I only had to connect a few jumper cables from the accelerometer-gyroscope to the Arduino Uno. Even though the build process was really simple there were many aspects of the accelerometer and gyroscope that I learned about. Some of the things I learned while working on this milestone was a more detailed explanation of how they work and what the accelerometer and gyroscope do. I also learned how to interpret the data that the accelerometer and gyroscope output. The components of this milestone work by using either the gravity or small movements or vibrations using the piezoelectric effect or by sensing the difference in capacitance. The gyroscope sensor, it helps the gadget to detect its position and alignment in space. It creates a 3-axis dimensional virtual space which helps this gadget to check its alignment in it. An accelerometer is a compact device designed to measure non-gravitational acceleration. When the object it’s integrated into goes from a standstill to any velocity, the accelerometer is designed to respond to the vibrations associated with such movement. This then gives off the data in an X, Y, and Z form. The Arduino Uno is a microcontroller board that takes care of the processing and allows for you to code it.

I reached my first milestone on my main project, which was making sure my accelerometer-gyroscope works with an Arduino Uno. The accelerometer-gyroscope outputs the data as to where the project is in space and the acceleration of the project in three linear axes.

DIY Activity Tracker



The process of building was pretty rough in the beginning for me but smoothened out towards the end of the building process. Some of the roadblocks I had during my building process was that I soldered on the wrong resistors in the beginning and had to desolder it using the suction pen which required a lot of time and patience. The desoldering process, in the beginning, cost me a lot of time and delayed my completion date by a day. Another roadblock I bumped into was my wires weren’t securely attached to the circuit board. This made me think of a better solution so that the wires would be securely connected, I eventually came up with the solution of attaching the metallic area of the wire flatly onto the circuit board and that worked and soldered it on like that. I learned about the functions of many of the components that were included in the MiniPOV3 such as the microcontroller, zener diodes, and resistors and how they are classified along with parallel and series types. The purpose of the microcontroller is to do the processing in the MiniPOV3 and is the part that allows for the customization of the LEDs. The zener diodes essentially blocked the current from going a specific way in a circuit and the resistors reduce the current flow and adjust signal levels. Parallel and series are two ways that components can be set up. The advantage in a series type is that it will provide double the voltage written on the battery and a parallel type is that there is more capacity than a series type.

I finished my Mini Persistence Of Vision (POV) 3 device. The MiniPOV3 is a device that can show customizable images by shaking the POV around through its eight Light Emitting Diodes (LEDs). The MiniPOV3 works when the switch on the battery is turned on and the current goes to the microcontroller which determines which and when a LED turns on. The microcontroller is the part that can be programmed to display a customized message when the MiniPOV3 is shaken side to side.


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