ESP32-C3 0.42″ OLED Development Board – Mini WiFi + BLE Module

SKU: FA1053-1-1-4
Microcontroller

ESP32-C3 (32-bit RISC-V single-core)
Clock Speed

Up to 160 MHz
Flash / SRAM / ROM

4 MB Flash / 400 KB SRAM / 384 KB ROM
Wireless

WiFi 802.11 b/g/n (2.4 GHz), Bluetooth 5.0 (LE)
Display

0.42-inch OLED, 72×40 pixels, SSD1306, I2C
GPIO / ADC

13 GPIOs (PWM), 4 ADC inputs
Operating Voltage

3.3V logic; 5V via USB-C
Dimensions

Approx. 25 × 15 mm

The ESP32-C3 0.42″ OLED Development Board is an ultra-compact IoT platform that integrates the ESP32-C3 RISC-V microcontroller with a built-in 0.42-inch OLED display, eliminating the need for external screens and wiring. Designed for wearables, portable sensors, and space-constrained projects, this board packs WiFi, Bluetooth 5.0, and a capable 32-bit processor into a thumbnail-sized form factor measuring just 25 × 15 mm .

At its core is the ESP32-C3 single-core 32-bit RISC-V processor running at up to 160 MHz, featuring 400 KB SRAM, 384 KB ROM, and 4 MB of onboard Flash for program and data storage . This architecture provides a modern, power-efficient alternative to traditional microcontrollers, with excellent performance for connected applications.

The 0.42-inch OLED display is driven by an SSD1306-compatible controller and connects via I2C (SDA on GPIO5, SCL on GPIO6, default address 0x3C) . With a 72×40 pixel resolution, it is ideal for displaying sensor readings, status indicators, and simple user interfaces . Developers should note that while the physical resolution is 72×40, some libraries may require configuring a 128×64 buffer with offset adjustments to render correctly .

Wireless connectivity includes WiFi 802.11 b/g/n on the 2.4 GHz band and Bluetooth 5.0 (LE) with Bluetooth Mesh support, enabling versatile IoT applications . The board uses an onboard ceramic chip antenna for reliable wireless performance in a compact footprint .

The board is supported by the Arduino IDE, ESP-IDF, and MicroPython, with extensive community libraries including U8g2 for OLED control . The USB-C connector handles power and programming, and the board includes reset and BOOT buttons for easy operation . An onboard blue LED on GPIO8 provides visual feedback for testing and debugging .

Whether you are building a wearable health monitor, a smart home sensor with local display, a portable data logger, or a compact IoT device with user interface, the ESP32-C3 0.42″ OLED Development Board offers a powerful, integrated foundation in an exceptionally small package. It is suitable for individual makers, students, and businesses purchasing in bulk for product development or educational programs.

Features

  • ESP32-C3 RISC-V single-core processor — 32-bit architecture at up to 160 MHz with 400 KB SRAM and 384 KB ROM

  • Integrated 0.42-inch OLED display — SSD1306-compatible, 72×40 resolution, I2C interface (SDA=GPIO5, SCL=GPIO6, address 0x3C)

  • WiFi & Bluetooth 5.0 — 802.11 b/g/n and BLE with Bluetooth Mesh support

  • 4MB onboard Flash — Sufficient storage for programs and data

  • Ultra-compact form factor — Thumbnail-sized at approximately 25 × 15 mm

  • Onboard ceramic antenna — Reliable wireless performance in a compact footprint

  • USB-C connector — Modern, reversible connector for power and programming

  • Onboard LED & buttons — Blue LED on GPIO8, plus reset and BOOT buttons

  • Qwiic I2C connector — Plug-and-play connection for Qwiic ecosystem sensors

  • Wide development support — Arduino IDE, ESP-IDF, and MicroPython compatible

Technical Specifications 

# Parameter Specification
1 Microcontroller ESP32-C3 (32-bit RISC-V single-core)
2 Clock Speed Up to 160 MHz
3 Flash / SRAM / ROM 4 MB Flash / 400 KB SRAM / 384 KB ROM
4 Wireless WiFi 802.11 b/g/n (2.4 GHz), Bluetooth 5.0 (LE)
5 Display 0.42-inch OLED, 72×40 pixels, SSD1306, I2C
6 GPIO / ADC 13 GPIOs (PWM), 4 ADC inputs
7 Operating Voltage 3.3V logic; 5V via USB-C
8 Dimensions Approx. 25 × 15 mm

Usage

Getting Started

  1. Connect via USB-C — Use a USB-C cable to connect the board to your computer. The board is powered and ready for programming.

  2. Install board support — In Arduino IDE, add the ESP32 board manager URL (https://espressif.github.io/arduino-esp32/package_esp32_index.json) and install the ESP32 package via Boards Manager .

  3. Select the board — Choose an appropriate ESP32-C3 board definition (e.g., “ESP32C3 Dev Module”).

  4. Install OLED library — Install the U8g2 library for controlling the SSD1306 display .

  5. Upload your sketch — If uploading fails, hold the BOOT button, press and release RESET, then release BOOT to enter download mode.

  6. Test the OLED — Use a simple U8g2 example to verify the display works. Note that the 72×40 resolution may require offset adjustments in the library .

OLED Configuration Notes

  • I2C Pins: SDA = GPIO5, SCL = GPIO6 (default)

  • I2C Address: 0x3C (default)

  • Resolution Handling: The U8g2 library does not have a native 72×40 constructor. Common workaround uses the 128×64 constructor with xOffset=30 and yOffset=12 to center content .

Typical Applications

  • Wearable devices — Compact size with integrated display for fitness trackers and smart watches

  • Portable sensors — Local display of temperature, humidity, or other sensor readings

  • Smart home devices — Connected switches and controllers with visual status

  • IoT data loggers — Display of logged data without external screen

  • Educational projects — Learning RISC-V and ESP32 development with integrated display

  • Space-constrained prototypes — When a separate display would add too much bulk

Notes for Business Buyers

  • Integrated display eliminates external components — Reduces BOM cost and assembly complexity.

  • Ultra-compact form factor — Ideal for wearables and portable products.

  • RISC-V architecture — Modern, efficient processing with strong toolchain support.

  • Suitable for bulk purchasing — Compact size and integrated features make it practical for product development and volume deployment.

Q: What is the ESP32-C3 0.42" OLED Development Board used for?

It is a compact IoT development board with an integrated OLED display, designed for wearables, portable sensors, smart home devices, and space-constrained applications requiring WiFi and Bluetooth connectivity with local visual output .

Q: What resolution is the OLED display?

The display has a 72×40 pixel resolution and uses an SSD1306-compatible controller .

Q: How do I connect the OLED display in my code?

The OLED uses I2C with SDA on GPIO5 and SCL on GPIO6, with a default I2C address of 0x3C

Q: Why doesn't the U8g2 library have a 72×40 constructor?

The U8g2 library does not natively support the 72×40 resolution. The common workaround is to use the 128×64 constructor and apply xOffset=30 and yOffset=12 to center the content on the display .

Q: What is the deep sleep current of this board?

The ESP32-C3 supports low-power modes suitable for battery-powered applications. For specific deep sleep current figures, refer to the ESP32-C3 datasheet .

Q: How do I enter download mode?

Hold down the BOOT button, press and release the RESET button, then release the BOOT button. The board will enter download mode for firmware flashing .

Q: What development environments are supported?

The board supports Arduino IDE, ESP-IDF, and MicroPython, with community libraries including U8g2 for OLED control .

Q: What is the operating voltage?

The board operates at 3.3V logic. It can be powered via USB-C (5V) .

Q: Does this board support Bluetooth 5.0?

Yes. The ESP32-C3 supports Bluetooth 5.0 (LE) with features including Bluetooth Mesh .

Q: Can I purchase in bulk for a product development project?

Yes. This board is suitable for both individual users and business purchasing, including product development, IoT integration, and volume production. The integrated display and compact form factor make it practical for commercial products.

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