A compact, versatile, and ultra-low-power development board.

Engineered for maximum power efficiency and flexibility. It features a unique dual-mode power system, a 4-layer PCB for improved RF performance, and a compact form factor with castellated edges, making it ideal for both battery-powered IoT prototypes and integration into larger projects.

The design prioritizes hand-assembly by using 0805 and larger SMD components where possible.

Key Features

• Dual Power Modes: A slide switch selects between a regulated input (REG on the board) for standard LiPo batteries/USB power or a direct-to-MCU bypass for ultra-low-power LiFePO4 operation (DIR on the board).
• Ultra-Low Deep Sleep: Designed to achieve ~5µA deep sleep current in Direct Mode by bypassing the voltage regulator entirely.
• Compact & Integratable: A minimal footprint with castellated holes on the edges allows the board to be soldered directly as a module onto a parent PCB (or solder header pins).
• ESP32-C3 Antenna Support: The layout accommodates both the standard ESP32-C3-MINI-1 with a PCB antenna (overhanging the board) and the ESP32-C3-MINI-1U variant with a U.FL connector for an external antenna.
• Onboard Connectors: Includes a JST-PH connector for batteries and a dedicated 4-pin header for easy programming.
• Improved RF Performance: A 4-layer PCB with dedicated ground and power planes helps reduce noise and improve radio signal integrity.
• Hand-Solder Friendly: Uses larger 0805 components for capacitors and resistors, making it easier to assemble by hand.

Power System Explained

The board's most unique feature is its slide-switch-controlled dual power system.

1. Regulated Mode (for LiPo / 5V USB) [REG]

In this mode, power from the JST connector is routed through the onboard RT9080 Low-Dropout (LDO) regulator. This allows you to safely power the board with a standard 3.7V (4.2V max) LiPo battery or a 5V USB power source. This mode is ideal for development or applications where the LDO's quiescent current (typically a few microamps) is acceptable.

2. Direct Mode (for LiFePO4 - Ultra-Low Power) [DIR]

This mode bypasses the LDO regulator entirely, connecting the battery's positive terminal directly to the ESP32-C3's 3.3V rail. This eliminates the regulator's quiescent current, allowing the board to achieve its lowest possible deep sleep power consumption (~5µA). This mode is specifically designed for 3.2V (nominal) LiFePO4 batteries.

Programming

The board does not have a USB-to-UART converter to save power. You must program it using an external 3.3V FTDI programmer connected to the 4-pin PROG header.