The Weather Station That Fits in Your Pocket
Shrink your weather station with this tiny build that packs full climate sensing into a footprint smaller than a wristwatch.
A weather station build is a classic project for an electronics hobbyist. These devices are typically designed to sit on a desk or table, much like a traditional barometer or an analog clock, blending functionality with a piece of decorative tech. But the Curious Scientist has just created a new type of weather station that may appeal to those who don’t want to take up a bunch of desk real estate with their build.
The Curious Scientist’s device is smaller than a wristwatch, giving you the information you need without any unnecessary bulk. It was created from several tiny, off-the-shelf development boards, so building your own is as easy as making a few connections and flashing the firmware.
At the core of the build is the CH32V003J4M6 microcontroller, a tiny RISC-V–based chip mounted on a custom miniature development board. The board is designed to be only two rows wide, allowing it to sit neatly in the center of a breadboard during development. Despite its small size, the microcontroller is powerful enough to handle the sensor calculations and drive a display. The board even includes a USB-C connector for power, although programming the chip requires a dedicated WCH-LinkE programmer.
To gather environmental data, the project uses a BME280 sensor, a compact MEMS device capable of measuring temperature, humidity, and atmospheric pressure. While the raw sensor operates at 3.6 volts, the module used here includes built-in voltage regulation and level shifting, allowing it to work comfortably with a 5-volt setup. For displaying the results, a tiny 0.42-inch OLED screen shows the current readings in real time.
Both the sensor and the display communicate with the microcontroller through the same I2C bus, keeping the wiring minimal. Even so, the build wasn’t entirely plug-and-play. The pin layouts of the two modules differed slightly — while the data lines matched, the power and ground pins were reversed. That meant a bit of creative wiring was required to cross the power rails correctly and ensure everything worked together.
Once the firmware was tested on a breadboard, the project moved toward a more permanent form. The creator selected modules that were all the same width — four pins across — allowing them to be stacked into a tidy, compact column alongside the microcontroller board. The resulting electronics stack is very small and uniform.
The final device is housed inside a simple two-piece 3D-printed enclosure. A side opening exposes the OLED display, while a small hole at the end allows airflow to reach the sensor. Because the fit inside the enclosure is so tight and the device isn’t expected to experience much mechanical stress, the lid is simply glued in place with superglue rather than secured with screws.
The BME280 outputs raw ADC values rather than finished measurements, meaning the microcontroller must first retrieve calibration data stored inside the sensor. Using formulas from the sensor’s datasheet, the firmware combines the raw readings with these trimming parameters to calculate accurate environmental data before displaying the results.
The end result is a fully functional weather station that fits in an incredibly small package. You won’t need to clear any space off your desk if you build this device.