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A BT 4.0 fitness-tracking smart watch for Android+iOS with a 1.5" color OLED display, SD card, NFC, wireless charging, and precision IMU

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This project was created on 06/04/2014 and last updated 2 days ago.

The time has come for me to combine all the knowledge I’ve gained through my watch prototypes and create the ultimate watch. The Walltech Smart watch. I’ve finished planning the design, the PCB is complete, and it’s set to be finished by the end of the summer of my sophomore year in high school. Sporting a beautiful 1.5" full color OLED display with sd card slot, bluetooth 4.0 low energy capability for receiving phone notifications, email, calls, texts, and maybe even music, we shall see how far I can take it. Ever wanted a smartwatch that you could customize to the core? Build yourself? And trust is fully open source? Look no further, from the experience I've gained building my previous generation OLED watch, I am fully ready to embark and have already ventured out on the journey that is creating my own smart watch.

MAKE MAGAZINE - The Open-Source Smartwatch Built by a Teenager:

The full writeup for the original OLED watch I built and an in-depth description and pictures of the various parts going into this build can be found using the links to the lower left.


The majority of the project's info and progress will be detailed in the project logs below, check them out!

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                                                        Open Source Licenses

Creative Commons License
This work by Walltech Industries is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Largely based on a work at
Creative Commons License
Walltech Images and logos by Walltech Industries are licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

                                                              System Design

                                                              Judging Criteria

  • 1 × IMUduinoBTLE The latest from Femtoduino, the IMUduinoBTLE uses an atmega32u4 from Atmel bootloaded as an Arduino Leonardo and a Nordic nRF8001 bluetooth 4.0 low energy chip and support components to connect to compliant devices and receive notifications for the watch. It’s tiny size and low power consumption make it perfect for use in this low power application. Now with an on board IMU, the IMUduinoBTLE has 10 DOF IMU incorporating a 10cm accurate barometer/altimeter, 6-axis digital compass, and 3-axis gyroscope/accelerometer, enabling complex motion and the precise altitude to be implemented by the user!
  • 1 × 1.5″ full color OLED display with onboard microSD card slot from Mike Rankin A step up from the monochrome .96″ OLED display of v4.2, this screen also consumes very little power thanks to the OLED technology behind it and can show beautiful images that will be the GUI for the smart watch. Now that there’s an sd card on board, I can use fancy graphics and make it look professional and keep the code to the microcontroller, enabling more to be coded instead of storing images too.
  • 1 × 3D Pedometer Module from Nicerf This tiny, tiny module will connect to the watch’s I2C lines as the DS1307 does, and counts steps using a tiny accelerometer and buffer memory. It’ll be used to add fitness tracking capability to the watch and in conjunction with the phone app, keep track of calories burned and activity levels! Oh, and did I say this thing was tiny?
  • 1 × Samsung NFC Tec Tile An advanced NFC tag that when placed under the OLED screen's glass, will allow users to scan the watch with their phones and automatically connect themselves to it via bluetooth, and open up a web page with documentation and source code!
  • 1 × QI Inductive Power Receiver Made for the Galaxy S5, this small card with an embedded coil receives up to 750ma at 5V from a QI compatible base station to charge the watch's lithium ion battery wirelessly.
  • 1 × DS1307 RTC A trusty real time clock, forms the backbone of the timekeeping functionality a watch is useful for.
  • 1 × MCP73831 Charge Controller Charges the battery and provides charge status information.
  • 1 × 500mAh Lithium Polymer Battery The battery that powers the watch. With how things are looking, an 18-24 hour battery life is to be expected.
  • 1 × Flickable Side-Mounted Selector Switch
  • 1 × Vibration Motor for notifications

Project logs
  • Quick Update

    2 days ago • 0 comments

    After testing showed the OLED io pin choices would work, and I was fully confident in assembling the prototype, the second I sat down to assemble it, the microSD card fell out of its slot, and I discovered the mechanism no longer worked. Two weeks ago, Mike was kind enough to send some replacement card slots for me to repair it with, but they've been lost in the mail, and so two more are coming via air and I hope they arrive shortly. That aside, during these weeks, I've made great progress on the firmware and android companion app, but have reached a point where I need help as detailed here: With less than two weeks left, if my sd card slots come in time, I'm confident I'll have a functional prototype, and with the code I've written and tested so far, it should be enough to meet the deadline requirements. I'll do some CAD and mock up another "artists render" of what it will look like, and will polish up the documentation here to best support the guidelines.

  • Prototype *Almost* Complete

    13 days ago • 0 comments

    Labor day weekend I had some time to populate the pcb for the smart watch and do some preliminary testing, but left off the expensive IMUduinoBTLE and OLED display until I was fully confident in the design. After all the ICs and passives were soldered on by hand with my Hakko 888D, I probed the regulator and tested the power circuit, and it all worked perfectly. Next I soldered pin headers to the IMUduinoBTLE, as it'll need headers wether this prototype works or not, and press-fit it into its place on the board. I also fit the OLED display into it's row of pins, and with my tongue at the right angle, held everything to the pins made contact. Upon powering it up, my test image showed on the OLED, and the screen could refresh, and then I lost concentration and lost connection. The OLED is very very picky about having a solid connection to work at all, so I was half expecting this not do anything. I now know that the IMUduinoBTLE can run the screen with the pins I chose, and the power is routed correctly. \o/ All I need now is to find a suitable place to mount the vibration motor, and a free day to work on it, and I'll have a functional prototype to test the software I've already written for it! Can't wait!

  • GUI Toolbar Concept Test

    22 days ago • 0 comments

    I mocked up some toolbar icons in photoshop for the smart watch GUI today and tested them out on the display when I got home from school. I played around with colors until I found the perfect grey for the toolbar, and after setting some alignment and measurement standards form myself, created a concept GUI that I really like and will stick with in the final software. The icons from right to left are the charging icon, bluetooth connected icon, and bluetooth disconnected icon. Obviously both bluetooth icons won't be on at the same time, but rather with boolean connection values coming from the Nordic nRF8001 will reflect the current bluetooth state of the watch. The time from the DS1307 and temperature from the IMUduinoBTLE's barometer will appear on all non-watch face screens, and will disappear when switched to a time face. When showing a time face after waking with a tap, pressing the side button will show the toolbar and show the number of notifications and the information mentioned above.

View all 24 project logs


Mark Jeronimus wrote a month ago null point

Oh another promising watch. I LOVE THIS TOO. I was searching for smart watches that I can program on and came back empty every time. The Pebble doesn't multitask, the TI doesn't have matrix display, the WIMM, Sony, i'm Watch and others don't have enough buttons, are Android (overkill) or don't last long (not to mention that I can't verify my specific requirements without hands-on experience)

I want a wrist-device with RTC (doh), matrix display that's always on (even when stationary), easily programmable, lasts 20 hours on a charge, and at least four buttons (for up, down, enter and back). Will yours be able to do this once finished?

Are you sure? [yes] / [no]

Walltech wrote a month ago null point

Most certainly! The 500mah battery should give it plenty of run time according to rough calculations and rounding up, but I'll test it for sure when it's complete, and it's a fully featured Arduino Leonardo so the convenience and community surrounding the Arduino microcontroller is at your disposal. The flick switch on the side has an up down and push in state, and with the on board accelerometer, a tap on the screen will be the fourth 'select' state. The reasoning you cited is half of why I've created this watch, the other half being the fun of planning designing and building it, I'm glad you like it. This watch is also cross compatible with iOS and Android to, so unlike every other smart watch in existence, anyone with either device can develop and use the full feature set of the watch as well as the unique features you've pointed out.

Are you sure? [yes] / [no]

Mark Jeronimus wrote a month ago null point

That's great. Although I really want the rock switch to do enter and have a separate microswitch on the left or something (not the same height to prevent pushing both at the same time). I own the same rock switch btw, salvaged from an USB MP3 player.

We really need people your age! I bet you're getting a lot of eyes because what you're doing is not typical for people your age, but when I was about 14 I started hacking together lots of stuff and studied boolean logic, digital signal processing and 3D raytracing, which are normally advanced college courses. When I grew older I stayed the same geek but with increasingly many ideas and less time on my hands I could barely finish any project anymore, and after even more time the motivation for starting projects got lost altogether.

Are you sure? [yes] / [no]

Walltech wrote a month ago null point

I've definitely gained much attention with this project, Make: interviewed me and wrote an article, and my website and twitter have been exploding with curious and very supportive people. I'm warmly appreciative of all the support that I've received and am genuinely happy and excited so many in fact are interested. Watch this space for a prototype very soon!

Are you sure? [yes] / [no]

Jared Sanson wrote a month ago null point

Nice project, I too am building my own OLED smart watch :)
What kind of battery life do you get?

Are you sure? [yes] / [no]

Walltech wrote a month ago null point

I don't have an assembled prototype as of right now, that'll change very shortly, and one of the things to test is power consumption and battery life. It should definitely last over a day with 500mah, it's probably closer to 2 or 3.

Are you sure? [yes] / [no]

Shraavan Bandaru wrote 3 months ago null point

I am really impressed with your project! Are planning to add a touchscreen to your watch?

Are you sure? [yes] / [no]

Walltech wrote 3 months ago null point

Hello! Thanks for the interest! At the moment, no, I'm not planning to add a touch screen as I haven't worked with one before and so it wasn't a part of the design process. The 3 way switch is spring loaded, tactile, and feels good to casually flick up and down, and is in the perfect position on the watch to place your thumb on the left side, your middle finger in the middle of the switch's side, and actuate the switch with your index finger. Add a flowing UI and the switch should be more than enough and as simple as a touch screen to use. I have thought about it, but I'm not quite sure if they're made to my size or how to support them with arduino in hardware or software. Thanks for your question!

Are you sure? [yes] / [no]

Walltech wrote 2 months ago 1 point

As now that the watch has such an incredibly accurate 9 DOF IMU, I scan detect taps on the screen with the accelerometer and use the spring switch to swipe up and down. You could tap on the sides of the watch to navigate that way too. Tilting to scroll when the watch is awake, anything really. You could hold a magnet and use it as a stylus with the magnetometer, there are an incredible amount of features I can make use of, and you can too with the open source code!

Are you sure? [yes] / [no]

Jasmine wrote 3 months ago null point

You should still submit it asap as community voting starts soon. It doesn't have to be finished at this point. We want to see the evolution through the project logs. Hope you have a great time on your holiday.

Are you sure? [yes] / [no]

Walltech wrote 3 months ago null point

I'm looking for a way I can print and scan the form where I am. I would hate to miss out on entering before voting starts.

Are you sure? [yes] / [no]

Jasmine wrote 3 months ago null point

Hello Walltech, I'm really impressed with your project. Can't wait to see it develop over the summer.

btw - we've updated the submission process for The Hackaday Prize, so if you want to *officially* enter this project - login and use the 'submit to' under your project images on the left hand side.

Also, we're starting community judging shortly, so now is the time to make sure you've added info to the project so people can see why you should win The Hackaday Prize. You might also like to add a few more details to your profile page, so we can get to know you better.

Got any questions? Give me a shout. Good luck

Are you sure? [yes] / [no]


[this comment has been deleted]

Walltech wrote 3 months ago -1 point

Thanks for your interest! I won't have access to a printer/scanner for two more weeks as I'm on vacation, and as soon as I get back, I'll be officially entering the contest with the form. I'll be sure to apply your advice to the project page too! Thanks!

Are you sure? [yes] / [no]