Having a system in your living room that displays weather information and facts is handy, and setting up one particular of people is a great venture if you appreciate tinkering with microcontrollers and environmental sensors. It is also a wonderful way to understand about reduced-electrical power structure, as [x-labz] demonstrated with their e-ink weather conditions station which will work for no less than 60 times on a one battery charge. It has a obvious screen that exhibits the community temperature and humidity, as well as the weather conditions forecast for the working day.
The screen is a 4.2″ e-paper module with a resolution of 400 x 300 pixels. It takes advantage of just 26 mW of electric power for a couple seconds when it updates its graphic, and fundamentally zero watts when demonstrating a static picture. It’s pushed by a tiny ESP32C3 processor board, which downloads the weather conditions forecast from weatherapi.com each two several hours. The indoor local climate is calculated by an SHT-21 temperature and humidity sensor mounted behind the display screen, while the out of doors info is gathered by a WiFi-connected sensor mounted on [x-labz]’s balcony.
The important to acquiring reduced electric power utilization below is to preserve the ESP32 in slumber manner as a lot as probable. The CPU briefly wakes up when every five minutes to go through out the indoor sensor and at the time each individual fifteen minutes to obtain facts from outdoors, using the somewhat ability-hungry WiFi module.
To further more cut down electric power intake, the CPU main is driven at the most affordable possible clock pace at all periods: 10 MHz when reading the indoor sensor, and 80 MHz when using the WiFi link. All of this will help assure that just 1 600 mAh lithium battery can preserve all the things jogging for all those 60 times.
E-ink shows are perfect for text and easy graphics that really don’t change too usually, which is why they are pretty preferred in temperature stations. With a bit of tweaking though, LCDs can also be optimized for lower electric power.