sorengilkeyjohnson/lowlora

This repository contains the hardware design for a tiny environmental sensor board that runs on solar power with no battery. The board measures 23 by 25 millimeters, roughly the size of a postage stamp, with the entire back surface covered by a solar cell. It collects temperature, humidity, and barometric pressure readings and transmits them wirelessly over a long-range radio protocol called LoRa. The central engineering choice is using a supercapacitor instead of a battery. A supercapacitor charges quickly from the solar cell through a dedicated energy harvesting chip, and the microcontroller cuts power to the radio and sensors between transmissions to keep idle power draw as low as possible. The result is a node you can deploy outdoors and leave without any maintenance. The radio chip operates at 915 MHz and connects to an external antenna through an MMCX connector. Sensors for temperature, humidity, and pressure communicate with the microcontroller over a two-wire interface. The board uses a four-layer PCB with a split power plane to keep the radio section electrically clean. This repository covers only the hardware, not any software. What is included: the KiCad schematic and PCB layout files, a complete bill of materials, Gerber files for sending to a PCB manufacturer, and a pick-and-place file for automated assembly. You would need to write your own firmware to actually operate the board. To order a physical board, you send the Gerbers to a PCB manufacturer and the BOM and pick-and-place file to an assembly service. An MMCX-compatible 915 MHz antenna is not included in the repository and must be sourced separately. The README points to a LICENSE file but does not name the license type.