For some unknown reason PC's are dumber than smartphones. This device does help to make PC's smart by adding sensor.

Introduction: Hack Computer to Make It Smart!

Have you ever wondered why smartphones are called smart-phones? Because they are smart, right? They do some works automatically, smartly. That's the short answer. I was thinking something, even if computers are a lot more powerful than phones, why aren't they smart! For instance, mobile phones have automatic brightness control system, which is handy and I use it always. But for some unknown reasons, computers don't have automatic brightness control system. In order to change brightness, every time I have to press some buttons (function keys). And in some computers, some key combination does the work (usually fn+function-key). I find that pretty annoying. So I designed a simple device that can be connected on any pc and the pc's brightness will be automatically controlled, just like our phones. Let's see how I made my PC smart.

Step 1: Parts

Electronics -

  • Arduino (I used Pro Micro) -1x
  • LDR - 2x
  • 10kr - 1x
  • Brightness Controller PCB [link] - 1x
  • Female headers

Others -

  • USB cable (compatible with Arduino board)
  • Soldering tools
  • And some cutting tools

That's it.

Step 2: Principle - How Does It Work?

It's always good to discuss about what we are making before jumping. A little theory is good enough to jump start.

I needed some kind of sensor to detect light intensity. LDR or light dependent resistor is best suited for that. LDR will face the person (just like phones sensor face front/person) and get light intensity data. The data will be read by Arduino. That's analog data ranging from 0 to 1024.

If we map the values (0 - 1024) we can control brightness. I tried using Arduino 'keyboard' library to press function buttons using Arduino. That doesn't work and it also freezes hardware keyboard (as the pc knows keyboard is already working).

So I am sending the sensor data to a python program that runs on the PC. And python does the rest, I mean controlling brightness.

Now, let's start making.

Step 3: Making and Testing Circuit/concept

To prove my concept I first made the circuit in bread board. And wrote a simple program to output the sensor data (light intensity data) over serial monitor of Arduino.

Here's the program that I wrote (download from github)-

Step 4: Design and Make PCB

I used the same circuit on easyEDA and designed a PCB (Printed Circuit Board). You can see that I used two sensors, actually that's just for design purpose. With two LDR it kind of looks like a snail. LDR_L is the LDR that is not being used.

Then I fabricated the PCB from PCBWay is one of the best and my favorite PCB manufacturer. With just 5$ I can get 10 PCB's! Anyway, I used their quick order page followed by quick order pcb section, uploaded my PCB and chose color. That's it! I think quick-order section is a blessing for all of us who don't know much, and just want to get it done. Get the PCB from here.

I used just black earlier, it was so shiny I tried matte black this time. After waiting for around 3-4 days, I got the beautiful PCB's. The quality is as always amazing. The pads, solder mask, silkscreen is just as perfect as they could be. I think I fell in love with matte black.

Step 5: Solder PCB and Complete Hardware

Now it's time to solder thing in place. It's simple as not much components are there. Soldered everything and made sure I did not inhale the smoke of soldering iron.

I used female headers as I am a plug and play guy. You can just solder the Arduino board itself on the board.


Step 6: Program the Board (Arduino Code)

Now it's time to upload the program of Arduino. Arduino uses Serial communication to send data to PC.

First of all I defined the sensor pin, the pin of Arduino where the sensor inputs data.

In setup function I started serial communication with a buad rate of 9600. Setup function runs only once every time we power the Arduino board.

Then in mainloop it gets data and sends over serial. A little delay of 200ms is kept to make it work smoothly.

Here is the complete code, download from here.

Opened Arduino.ide and uploaded the program to my Arduino board.

Step 7: Python Programming (for PC)

As we discussed earlier, Arduino sends data to Arduino and python does the rest. So I wrote a simple python script.

Anyway, If you don't have python installed install latest version from here. While installing make sure you have checked the box that says 'add python to environment variable path'.

Okay then I opened terminal and installed two libraries, Pyserial and screen-brightness-control using these commands ($ signs are to denote them as terminal command, copy without them)-

After installing that I wrote the whole code. But let's break it to you guys a bit.

Here I import libraries to use them. '' is needed to detect Arduino board automatically.

This section gets usb ports automatically and tries to connect with Arduino

This is the function that converts Arduino data (from 0 to 1024) into %data - from 0 to 100. It's called mapping. Python map function does something else, so I had to write it (took some help from internet though).

Anyway, it's always best to close something you opened after use, whether it's conversation or port.

Now, I opened my favorite python editor and ran the program. Download the full program from github.

Step 8: Plug and Play!

Finally I connected the board to my PC with a USB cable. Then ran the python program. You can see the rest in the video. It works like a charm! I have never been so satisfied of my work before.

Now my PC is a bit smart.

Happy Making!!!

Tips: to save power you might want to cut traces of arduino LED lights.

Ashraf Minhaj
A Computer Science and Engineering student and a Hobbyist. Love to make robots, DIY gadgets. Interested in robotics and AI.