Simple digital watch

In this project I will provide a step by step instruction to build a cool hackable watch like device.

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We have all seen the new smartwatches and the diy builds of them. But most of the time they are too expensive or too complicated to build. So I build this very simple and hackable watch.

Arduino pro mini

Arduino pro mini

This project is very simple because at the core it uses a Arduino pro mini this small Arduino uses the same atmega processor as the Arduino uno so most of the libraries you will find online just work. with the same pinout.

OLED display


The display used in this project uses I2C to communicate with the Arduino because I2C uses only 2 data connections it is really easy to wire up. It is also just 0.96" this makes it ideal for wearables that need to be small and outside it will be easy to read because the display has a very high contrast.

Recycled Nokia battery

Nokia battery. Sorry I left the buttons on it.

A really important part of a wearable project is a battery! In this project I got a battery out of a old Nokia phone this battery was square so it fitted well for a watch. I don't have a charger on the watch Itself but I added a connector to the connections of the battery so I can charge it with the old phone that I took apart.

Recycled Nokia battery charger

ChargerThis is the old phone that I used nicely fitted in a recycled box. I extended the charger port and the connections for the battery so I can close the box and charge it.

Charger box closed

  • 1 × 0.96" OLED I2C display This display is small and uses very little energy
  • 1 × Nokia batery I use a salvaged Nokia display but you could use every small rechargeable battery.
  • 1 × Arduino pro mini 3v The Arduino pro mini is very small and uses the same atmega as the Arduino uno
  • 3 × Tactical buttons

  • New Strap and vibration

    bram01/03/2015 at 17:24 0 comments

    I finally added a "real" strap to it. I got some leather and learned sewing(Yeah! new skill), It wasn't that easy but I did it and it looks good enough for the first time sewing. picture of the watch with the new strap below:

    I also added a vibration motor that I got out of a other old phone. I will make it so that every hour it vibrates for a few milliseconds. You can see the vibration motor stick out in the picture above.

  • Watch code

    bram01/01/2015 at 22:28 0 comments

    Today I developed a simple piece of code that if I boot up asks for the current time and after that it will just say the time. In the video I show how it works.

  • Added strap

    bram01/01/2015 at 15:36 0 comments

    I made a very simple strap out of Velcro tape. It is very simple to use so it is great for any sort of strap. On the picture you see a tie wrap but that was just to hold it tie for the glue to dry.

View all 3 project logs

  • 1
    Step 1

    Wiring the buttons

    First of all solder the up and down buttons with one side together and but them on the battery. And next you need to solder the select button to the just soldered together pins. This power rail needs to be soldered to the VCC labelled pin on the Arduino.

    After these steps the connection should look something like this:

    The input pins

    You need to add a resistor(10KΩ) between all the input pins and the ground pin. alert! you need a resistor for all the pins. If you have done this wire all the buttons to the inputs you have just tight to ground. Sorry I don't have a picture of this part but it should be pretty simple.

  • 2
    Step 2

    Wiring the charging port

    This step is very simple but you need to be carefully to not overheat your battery. I soldered wires directly to the pads of the battery and wired them to the connector I secured on the battery with some foam tape.

  • 3
    Step 3

    Wiring the display

    To Wire the display you just need two wires for communication because it uses a I2C protocol and two for power so 4 in total. The two wires for the communication need to go to pin A4 and A5 and power to power. The wiring:

    • A4 - SDA
    • A5 - SCL
    • vcc - vcc
    • gnd - gnd

View all 4 instructions

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