Hao Wen's Crescent City Dev Board Aims to Offer a One-Stop Shop for Compact Espressif ESP32 Projects

Engineer Hao Wen is preparing a crowdfunding campaign for the Crescent City Dev Board, an Espressif ESP32-S3-based gadget with integrated 0.96" OLED display and lithium-polymer battery support — designed as a compact all-in-one for a range of use cases.

"Many ESP32 projects that need a screen start as a dev board, a display module, a charger board, and jumper wires between them," Wen explains of his thinking behind the board's design. "Crescent City puts those parts on one small board. The same hardware can be a desk clock, a status display for a server or a 3D printer, or a battery-powered sensor that shows its readings on its own screen. Plug a Qwiic temperature and humidity sensor (SHT4x) into the side connector, and an example sketch shows live readings and a chart with no soldering."

The board is based around an ESP32-S3-WROOM-1-N8 module, which dates from before Espressif's transition to the RISC-V architecture and features two Tensilica Xtensa LX7 cores running at up to 240MHz, 512kB of static RAM plus an additional 16kB available from the real-time clock, plus 384kB of on-chip flash storage alongside 8MB of off-chip flash. There's single-band Wi-Fi 4 and Bluetooth 5 Low Energy (BLE) connectivity, though the lack of reference to the latter in Wen's specifications for the Crescent City board suggests that only Wi-Fi will be available in the stock firmware.

The module is installed in a breadboard-friendly carrier that includes a 0.96" single-color 128×64 OLED display based on an SSD1306 controller, connected to the microcontroller over SPI, 12 general-purpose input/output (GPIO) pins of which seven double as analog inputs — though three of these share connectivity with the Wi-Fi radio, meaning that readings may not be available when Wi-Fi is active. There's single Qwiic/STEMMA QT header for solderless expansion, a user-addressable RGB LED, physical boot and reset pins, and a connector for an optional lithium-polymer battery with charging from the board's USB Type-C data and power port.

"[It] ships with an open-source Wi-Fi weather clock: local time, current weather, and the day's high and low, plus indoor temperature and humidity with a Qwiic sensor and a four-bar battery gauge estimated from the battery voltage," Wen says of the board's stock firmware. "Weather clock [is] setup from your phone, with no app or account needed. Programmable with the Arduino IDE (ESP32 board package, board "ESP32S3 Dev Module"). Ready-made ESPHome configuration for Home Assistant, with a browser installer and updates over Wi-Fi. Example sketches for a Qwiic temperature and humidity sensor and a battery-powered data logger."

Wen is planning to launch a campaign for the board on Crowd Supply in the near future, and has published a schematic (PDF) and a 3D model (STEP) ahead of launch — though these, it most be noted, are published as source-available with all rights reserved, meaning it's not possible to use them to build your own version of the board for private or commercial use. The firmware and program examples, meanwhile, will be made available under the permissive MIT license.