Introduction: Activity Tracker

Need a fitbit?

Hipster enough to want to go it your own way (and become a stud at your local coffee shop)? Or just a "hobbyist"? ;)

Leading an idle life that could do with a project?

Boy, can I fill your time! Just follow the easily laid out steps below, allow yourself to be swept away by my verbiage, and be ready to commemorate your victory with a jar of Jack.

And in the process, just think about all your friends in the coffee shop... even Ron.

Step 1: Great Expectations...


To produce an easily worn activity monitor capable of tracking a person's movement for at least a 24 hour period after which the data is processed and level of activity assessed. An accelerometer will be used as a pedometer.


- the air of mobility (battery powered and light)

- data recording for at least 24 hours onto an SD card

- carried on the arm via comfortable velcro straps


- Arduino UNO

- ADXL345 Accelerometer

- Adafruit Ultimate GPS Logger Shield (with an SD card writer)

- 4 GB SD card and adapter

- 9V battery and adapter for UNO

- GPS Antenna - External Active Antenna - 3-5V 28dB 5 Meter SMA

- SMA to uFL/u.FL/IPX/IPEX RF Adapter Cable

- Headers

- Soldering kit

- Rolls of velcro

Step 2: The First Assembly

Use the headers to attach the GPS module to the UNO, then solder the both together. Once done, solder the accelerometer to the module along the I2C configuration.

Step 3: Coding... and a Grim Realization

The materials were assembled and production of a viable code commenced. However, the limitations of the Uno quickly became apparent: all three functionalities of the device (writing to an SD, gathering GPS data, and gathering accelerometer data) cannot all work simultaneously. Two of the three work just fine, but the addition of the third completely knackers the device into inoperability (the accelerometer and GPS feed digital data to the device, which is then incapable of processing everything and accounting for all the necessary variables). Therefore, the pairing we chose was that of the GPS and SD card writing. However, adding complexity to the code of this pairing (such as writing to the SD only when the person begins moving and stopping when the person stops) was proven to be an impossibility as the same problems as before were met. These functionalities in the code were left (as well as the pedometer part) for future generations... and a better Uno.

Processing of the data occurs with the Matlab Code. The person extracts their data from the SD onto their computer, initiates the Matlab function, selects the .CSV file, and observes his or her activity plotted onto Google Maps.

Attached is the Arduino code, Matlab code, and three .CSV files that serve as examples for the Matlab function.

Step 4: The Second Assembly

For full mobility, and to test for yourself, make sure to first insert the SD card into the writer. Then attach the antenna adapter to the antenna, the adapter to the module, an optional magnet to the case that will hold the magnetized bottom of the antenna to the case, and revel at your handiwork. Lastly, attach the grating half of the velcro Yin/Yang to the case. This will allow for, as you will see later, comfortable operation.

Step 5: Nearly Out the Door...

Then take two strips of the comfortable half of the velcro Yin/Yang and attach on both ends, wrapping around so as to keep the antenna and its ungainly wires fastened. Use the remaining length to wrap around your arm. Use of a third strip of velcro is necessary to secure the battery to yourself and the device.

Step 6: It's Uphill From Here

You are finished! Enjoy that Jack and bask in the glory of Ron's jealousy.