Cookiemonsterwave lives in the San Francisco Bay Area, and BART (Bay Area Rapid Transit) helpfully provides an API that includes live train schedule updates. All you have to do is make a request through the API, and you can find out what time the next train is expected to arrive. That sort of thing can, of course, be done with an app. But Cookiemonsterwave thought it’d be more helpful to have an analog meter that gives them a general idea of how much time they have left to catch the train.
To do that, they used an ESP8266 to make the BART API requests and to control the readouts. The primary readout is an analog panel meter, and the needle swings from “10 minutes or more” to “10–5 minutes left” to “5 minutes or less.” There is also a secondary readout in the form of a small OLED display, which is used for additional and more specific data, as well as the status of the device. That’s all housed within a simple 3D-printed enclosure. If you often find yourself hurrying to catch the train, this is a good build to replicate — assuming your city’s transit system has an API for live data.