Espressif’s ESP32 SoC has become a hardware staple in IoT projects, and for a good reason — it’s an inexpensive, low-power Wi-Fi/Bluetooth-equipped module with a ton of features packed into a small footprint.
That said, engineers, makers, and hobbyists have modified the tiny board to suit their specific needs, including Jarrett (of Jarrett Builds), who took the module and revamped the way it uses power by incorporating a lithium battery charge/protection circuit, allowing it to accept LiPo batteries, thus making it great for long-term field-deployed IoT projects.
“Part of the problem I’ve been seeing with inexpensive IoT dev boards, is that the design around the power system hasn’t been very good. Here’s my attempt to fix that. This is a battery-ready module with a proper lithium battery charge circuit, lithium battery protection circuit, power supply, and antenna, all in a 1 inch by 1-inch package.”
Jarrett designed the uMesh (the module can interact with other ESP32 modules, thus creating a Mesh Network) using a ESP32-PICO-D4, buck-boost power supply, and stamped metal antenna housed on a PCB with castellated headers that provide access to input/output/battery voltage, TX/RX pins, boot-mode selection, and GPIO.
Jarrett explains that as a result of the header positions, the board can be directly soldered to a larger host board, as well as provide 3.3V regulated output power if it’s supplied with battery power. His design implements a cutoff if that voltage hits 3V to prevent over-discharge, and will switch over to using another power source when accessed through USB or the headers. A complete walkthrough of his uMesh build, complete with all files and folders can be found on Jarrett’s project page.