For the first of an irregular series of ‘Widget of the Week’ in which members will share the fruits of their frighteningly serious AliExpress and Banggood habits, I bring you the module that started it all, the ESP-01. Intended for use in wireless serial applications, hackers soon found that it was field programmable and immensely versatile, not to say powerful – having not just far more memory and a faster CPU than the mainstream Arduinos but integrated WiFi with a pretty comprehensive IPv4 stack.
On the one hand it’s somewhat hamstrung by having just three i/o pins but on the other, it costs less than a pound and so small it can easily be integrated into existing things. Use of the deep sleep function allows it to run for over two years on a pair of AA batteries, making it ideal for remote sensor applications. There’s a lot you can do even with just three pins to control, such as read a one-wire temperature/humidity sensor, drive an LCD display or control individually addressable RGB LED strips. I’m seriously considering matching some up with DHT-22 temperature/humidity sensors so I could monitor my home to an unprecedented level of accuracy – perhaps even two per room, one on an inside wall and the other on an outside – to see how efficiently the heating energy is being distributed.
I’m working on some simple projects using these to bring to meets and for educational demonstrations. At those prices children could build something to take away for next to nothing. Head over to the wiki for more information.