Batman Key chain with ESP8266

01 Jan 2017

Have recently bought a small batman key chain from amazon. It has a small button when pressed lights the batman eye with white light and sounds a pathetic sound (:(). So I thought of opening it.


It has enough space to put some custom electronics. So I thought of customising it a bit. This is what it looks before customising.

opened keychain

This is what it looks when adding a little bit of electronics into it. It has an esp8266 with 3 SMD LED (Red, Green, Blue) that can be independently controlled. It has a small speaker (from a headset) which plays a pac man tone. It is powered with a 3.7 V Lipo battery with an option to charge with an USB cable.

inside keychain

Batman keychain is playing pacman tone… :) I know it’s a bit wierd, but couldnt find a good tone (which can be expressed as a piano tone like C4, B#2, …) for batman. Will replace it once found a better one.

Things to add further

  • Pressing for a long time will enable a hotspot
  • Option to change the tone by writing it to EEPROM on the go (ESP8266 has 512 bytes of EEPROM).
  • Option to play PCM encoded 8 bit WAV file.