I modded my Flux Capacitor USB Charger and turned it into an instant notification widget.

It can now be controlled through WiFi, which comes in handy when I get pinged on IRC or get important email.

Hack

I replaced the resistor used to power the flux circuit with a 3v3 SMD regulator that fit the resistor’s footprint. The regulator now powers both the flux circuit IC and the ESP8266 module.

GPIO2 and GPIO0 in the ESP8266 module are used to toggle the flux circuit and keep state respectively. Using custom firmware, GPIO2 is pulled low for half a second when we need to toggle the flux circuit. This is accomplished by connecting to the ESP module via TCP and sending one of the following commands:

TIME CIRCUIT ON TIME CIRCUIT OFF

When the flux circuit fluxes, the cathode-side of the LEDs is pulled low; I hoked up GPIO0 to the cathode of one of the LEDs and made it interrupt on falling edge. When the interrupt is triggered I set the internal state to fluxing, an internal timer is restarted every time the LED is turned on. When the time circuit is turned off, the timer expires and sets the state back to off.

Just in case it wasn’t obvious, we need to know if the time circuit is ON or OFF so that we don’t toggle it OFF when we want it to be ON by mistake.

Components

• ESP8266
• ThinkGeek Flux Capacitor USB Car Charger