Having a tool in your lounge that exhibits climate info is handy, and constructing a kind of is a good mission when you take pleasure in tinkering with microcontrollers and environmental sensors. It’s additionally an effective way to find out about low-power design, as [x-labz] demonstrated with their e-ink climate station which works for at least 60 days on a single battery cost. It has a transparent show that exhibits the native temperature and humidity, in addition to the climate forecast for the day.

The show is a 4.2″ e-paper module with a decision of 400 x 300 pixels. It makes use of simply 26 mW of energy for just a few seconds whereas it updates its picture, and principally zero watts when exhibiting a static image. It’s pushed by a tiny ESP32C3 processor board, which downloads the climate forecast from weatherapi.com each two hours. The indoor local weather is measured by an SHT-21 temperature and humidity sensor mounted behind the show, whereas the outside information is gathered by a WiFi-connected sensor put in on [x-labz]’s balcony.

The important thing to reaching low energy utilization right here is to maintain the ESP32 in sleep mode as a lot as doable. The CPU briefly wakes up as soon as each 5 minutes to learn out the indoor sensor and as soon as each fifteen minutes to assemble information from outdoors, utilizing the comparatively power-hungry WiFi module.

To additional scale back energy consumption, the CPU core is pushed on the lowest doable clock pace always: 10 MHz when studying the indoor sensor, and 80 MHz when utilizing the WiFi connection. All of this helps be sure that only one 600 mAh lithium battery can maintain all the pieces operating for these 60 days.

E-ink shows are excellent for textual content and easy graphics that don’t change too typically, which is why they’re very talked-about in climate stations. With a little bit of tweaking although, LCDs will also be optimized for low energy.