Introduction: DIY Digital Protractor Under <--13$

What if Your Ruler Scale converted in to Protractor .....

This Project is all about convert an ordinary ruler in to Smart Ruler having a extra feature of measurement of Angle.


Now, Make a list of Which Electronic Componet or other helpful Tools is required ....

Approx Cost : 13 $

  • Laptop with Arudino IDE Install
  • Other Important Part and Tools
    • Ruler Scale (On which whole Circitry is Fixed)
    • Plastic Box (In Which whole Circuitry is Fixed)
    • Hookup Wire
    • Soldering IRON
    • Soldering Wire
    • Male to Female wire
    • Doublesided tap
    • Gluegun
    • Wire cutter
    • Wire stripper

Thats all for Component..... Now we are ready to build Digital Protector

Step 2: How It Works..

  • Heart of this module here is ARDUINO PRO MINI , It is use here to handle all external Peripherals like ButtonPanel, OLED display and Gyroscope(MPU6050).
  • To Power up this module here we use 3.7v Lippo Battery which is capable to deliver upto 180mAH,to charge battery here TP4056 module used via 3pin Toggle Switch.
  • Here Gyroscope send raw data to Pro mini, by mathamatical calculation Arduino Pro mini find YAW ANGLE from it based on movement of scale(ruler) on which this module is sticked.
  • OLED display here use to display current angle with respected to taken refrence using button_2.
  • OLED and Gyrscope(MPU6050) use I2C Protocol to interface with Arduino Pro MINI.

Lets understand Button function:

Button_1 : Press to enter into Angle mode to measure angle.

Button_2 : for taking Reference form which you have to measure angle.

Button_3: for calibration of Module (In case of Temperature and humidty variation).

for better understanding see video of Working of Digital_Protector .

Toggle Switch :

Toggle Switch has two mode ON and OFF mode.

ON mode: To turn on module and measure angle.

OFF mode : 1) To turn off module

2) To charge module

[ NOTE: Don`t use ON mode for Charging It may Damage Your Hardware. ]

Step 3: Circuit Building

  • Make all connection as per shown in circuit daigram with compactness because we are fitting all circuit in plastic Box in order to make module very compact.
  • One thing is you need to take care about Yourself how to fit all electroincs stuff in plastic box because here I didn`t mention anyware how to fit all stuff in box.
  • [ Note : So, make connection as small as possible in to order to fit in the Plastic Box.]

Step 4: Firmware Uploding ...

For Uploading code you required ......

1)Host Computer with ArduinoIDE installed

2) Arduino Uno as a Programmer

3)u8lib library for OLED display handling

(After downloding u8lib library , unzip it and put it into your arduino library folder)

4)hardware module of Digital Protector on which Code will be uplode...

Now we are ready to upload our firmware to arduino Pro mini...

  • Code Uploading Step:

> take arduino UNO remove is controller from the board

> make a connection between UNO and PROMINI as describe in Photo

> Connect arduino UNO to host computer

> open Sketchbook of firmware in Arduino IDE

>Select COM port.

> Upload Code and Play with Digital Protector.

[Note : Keep all files in one folder as a scketchbook in order to sucessfully code uploading.]

Step 5: Limitation and Future Plan

  • Limitation : First and Main Limitation is it can Measure angle in Two Dimension only.Second limitation is SURFACE , Surface on which You will draw an angle is must be an static until whole drawing is not completed.Third limitation is environmental condition , due to change in environmental condition it may affect reading.Fourth is Body , For body we use ordinary plastic Box which can be cracked so it can be handle very carefully.
  • Futureplan : Future Plan is to make 3d desing of this module so it can resists environmental change and cracking of body and also it can measure angle in 3D.

I Thanks @Ravi Butani for guide this awesome Project and make is sucessful.

Thank for Reading my First Instrctables hope You enjoy it .....

This is our First Instructable Blog so your Comment , Critics ,Suggestion are welcome...

Nirav & Krushal