The project is now getting some interesting firmware upgrades. I recently upgraded the firmware to allow users to play games like Tetris and Snake on the badge using their smartphones. The older feature of displaying any text messgae) is still there. Cool isn't it?
Watch this video:
If you have ever fallen in love then you know how it feels. Your days become nights and the nights become your days. You feel high on air with increased energy and sleeplessness. With this much energy you wouldn’t be able to control yourself from expressing your love to your partner. Everyone has a different way of expressing love. Some buy things for their loved ones while others decide to make something special for them. Being a maker myself I decided to make something special for my valentine to make her feel special this Valentine’s day.
This was my first Valentine’s day ever so I decided to make it special by giving her a surprise, but later I couldn’t resist and told her that I am making an LED display necklace cum badge for her with a secret text message scrolling on it. She liked the overall idea but she also asked for an extra feature to change the text messages on desire. So I modified the design and added a bluetooth low energy to upload any text message to it using an android phone.
And that's her wearing the necklace :)
SCHEMATICS and PCB:
The github repo for the project can be found here. The design is pretty simple. I exported a heart shape DXF into KiCAD for the edge cuts and sticked to all smd parts to minimize the size of the circuit board. There are 128 (0603) smd LEDs in total arranged in 8 rows and 16 columns. Two 74HC595 shift resisters(daisy chained) were used to control 8 columns each. An 8 channel ULN2803 is used as a current sink for all the 8 rows. A XC6210B332MR LDO is used in the design to power the HM-11 BLE at 3.3V. I used HM-11 because of its small footprint size. The entire circuit is controlled by ATMEGA328p microcontroller and is powered by a small 320 mAh LiPo battery.