Make Your Own Smartwatch From An Old Cell Phone

Step 1

Scavenging Parts

What I’d like to do for this crazy/ambitions project is turn an old cell phone into a smartwatch. So obviously an old cell phone is required. The primary reason for this project is simply that I had an old cell phone laying around and wanted to find a creative way to repurpose it. The one I had is a Nokia 1100, but most other old cell phones would work, so long as you can find the schematics for the LCD online. Taking apart the 1100, there weren’t too many scavenge-able parts to choose from. First and foremost, there was the LCD screen, then I was also able to extract a vibrating motor, a small speaker, as well as a protective cover for the LCD. What you’re able to scavenge really depends on what type of phone you have, and how old it is. The older the phone, the more scavenge-able parts you will find.

Step 2

Figuring Out The LCD

Without a working LCD, we have no project, so I need to figure out how to get it working outside of the phone. The first step is to see if I can find a schematic for it online. Doing a search for “Nokia 1100 LCD”, I was able to find out a ton of information about it. I found that the LCD model number is PCF8814. I was also able to find a schematic that listed the pinouts.

This is a view from the back side of the LCD, so Pin 8 is on the far left when looking at the back. There are 9 pins, but one is unused, leaving 8.

  1. LED (Positive – 3.3v)
  2. VDD
  3. VDDI
  4. SCLK
  5. SDA
  6. GND
  7. CS
  8. RES

The pins on the LCD are very small, so in an effort to make them easier to connect to, I soldered wire from a ribbon cable to each pin, and then hot glued it all into place. So now I can connect each of the wires to a breadboard to make it easier to work with the LCD.

Step 3

Driving The LCD

Now that I have the LCD ready for connection, I need something to connect it to…something that can send text to it for display. The display driver that I chose was the Arduino, primarily because I can use an Arduino Uno for prototyping, and when I’m ready to cram it all into a watch, I can use the much smaller Arduino Mini. First I connected all the LCD wires to a breadboard, and then I began connecting wires to the Arduino. I added some resistors to the pins that connect directly to Arduino pins to keep the Arduino from burning out the LCD. Total, it was 4 x 1.8 kOhm resistors ad 4 x 3.3 kOhm resistors. Use the diagram below for resistor connections, but as far as LCD to Arduino connections, this is how I connected it:
LCD > Arduino
  1. LED > 3.3v (Moved to Pin 8 for custom on/off control)
  2. VDD > 3.3v
  3. VDDI > 3.3v
  4. SCLK > Pin 13
  5. SDA > Pin 11
  6. GND > GND
  7. CS > Pin 10
  8. RES > Pin 12

Here is the connection diagram:

Read more: Make Your Own Smartwatch From An Old Cell Phone

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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