arnav-hackpad

The arnav-hackpad is a mini-keyboard (or macropad) designed to act as an external number pad with navigation and mouse capabilities, too! It has 10 keyswitches and two rotary encoders. There is a PCF8574AT module (Input/Output pin expander), a top-mounted case, and two layers of keycodes.

Challenges

Making the macropad was super challenging, since each step of the way required deep research and analysis. It was my first time making something hardware related, so I had no idea how any of the software tools worked or how all the hardware would integrate together. I find it funny now that I spent hours trying to figure out which pin on the microchip I should put my keyswitch matrix wires on (the answer is any one of them!). And that was just the beginning. When making CAD models in Autodesk Fusion, I had to learn how sketches and extrusion work from square one. I looked at so many sources just to confirm my dimensions were correct. After I started making my hackpad in real life, I realized I had done so much wrong. The cable wouldn’t fit, and none of the keys worked! After 3 days of nonstop research, I decided to ask AI for help. First, I checked if my files were in the right spot. Then, I used a multimeter to check if electricity was flowing through the board. I ended up deciding to order pull-up resistors, which did the job by pulling the SDA and SCL lines to 3.3V when idle, making the communication system between the chips work. Additionally, to make a PCF8574AT Scanner work, I had to write TONS of code. Navigating through the challenges was difficult, but each one taught me something that brought me closer towards success.

Success

When I was holding the pull-up resistors in place and the terminal printed “0x38”, I knew I was onto something. I uploaded the code and watched my screen in shock as I clicked the keys and saw the correct outputs. I was shocked that I was not far from a triumph, one that I had longed for over almost three months, and after soldering the pull-up resistors in place, everything worked flawlessly! I am proud of myself for having the grit and determination to, in the first place, accept the challenge of making a macropad. I stayed up long nights debugging software and hardware issues, but it was all worth it. Along the way, I learned many foundational skills in mechanical engineering and firmware coding.

Creativity and Technicality

I have added a lot of tools to make this project easy to demo and make, while also including some touches of creativity to make the project more personal. On my slideshow, you can see and interact with all of the individual parts. There is a video to show all of the features of the macropad. On the plate next to the keyswitches, I have added a logo I created with my name on it. Instead of choosing the common sandwich keyboard case, I chose a top-mounted keyboard case to make the keys loud and firm. I took on the challenge to include an I/O expander, even though not many people in the hackpad slack page knew about it. If you want to make the macropad, I have a guide. You must know how to solder to create it. Make sure you double check everything you do, as one small mistake can have a tremendous impact. In the end, you’ll have a beautiful macropad.

To learn more about the hackpad and to see an in-depth description, visit my github README.