[Mike Diamond] was tired of climbing down (and back up) 40 stairs to check his mailbox. He decided to create a mailbox alert using the ESP8266 to connect to his WiFi. The idea was simple: have the ESP8266 monitor when the mailbox flap opened using a magnet and a reed switch. As always, though, the devil is in the details. [Mike] got things working with a little help and shares not only the finished design but how he got there.
To handle the sending of e-mail, [Mike] used the Blynk app. You often think of Blynk as a way to build user interfaces on an Android or iOS device that can control an Arduino. In this case, though, [Mike] used the library with the ESP8266 and had it send e-mail on his behalf.
The program was simple enough, but there was one problem: Keeping the device powered on and connected to WiFi all the time was a constant drain on the battery. That’s how [Mike] discovered there was a deep-sleep function available. Using this helped, but even waking the device up periodically was too much draw on batteries. It took a little change to the hardware, but eventually [Mike] and his friend [Amir] devised a way to only power up the device when necessary. As a bonus, the notification also reports the battery voltage, so you know when to charge the device.
We’ve covered Blynk before (not once, but twice). We’ve also seen mailbox projects. And if tweaking the internals of a normal mailbox isn’t your style, read up on how to build a super mailbox from the ground up.