Description Waveshare ESP32-S3-RLCD-4.2 is a fully reflective screen AIoT development board based on the ESP32-S3. The Waveshare-33298 version is the package with an included 18650 lithium battery, designed for low-power embedded interfaces, AI voice projects, sunlight-readable IoT displays, and desktop smart devices. This ESP32-S3 4.2inch RLCD development board combines an ESP32-S3-WROOM-1-N16R8 module, a 4.2inch RLCD fully reflective display, 300 x 400 resolution, 2.4GHz Wi-Fi, and Bluetooth 5 LE. The reflective LCD does not require a backlight, giving the board an e-paper-like viewing effect while offering faster refresh response than traditional e-Paper displays. For AIoT product prototyping, the Waveshare ESP32-S3-RLCD-4.2 also integrates audio, sensing, storage, RTC, and battery-management hardware. Onboard resources include an ES7210 ADC for audio processing, an ES8311 low-power audio codec, dual microphones, an external speaker interface, an SHTC3 temperature and humidity sensor, a PCF85063 RTC, a TF card slot, USB Type-C, UART, I2C, GPIO expansion, and a 18650 battery holder. Choose Waveshare-33298 when the battery-included Waveshare ESP32-S3-RLCD-4.2 kit is required for immediate portable testing. Features ESP32-S3-RLCD-4.2 AIoT development board with ESP32-S3 dual-core processor up to 240MHz. 4.2inch RLCD fully reflective screen with 300 x 400 resolution. Reflective LCD design requires no backlight and provides strong readability for ambient-light applications. Faster refresh response than traditional e-Paper, suitable for dynamic IoT status screens and smart clocks. Supports 2.4GHz Wi-Fi and Bluetooth 5 LE through the onboard ESP32-S3 module. Integrated 16MB Flash and 8MB PSRAM for more capable UI, audio, and AIoT applications. Dual-microphone array with ES7210 for audio algorithms such as noise reduction and echo cancellation. ES8311 low-power audio codec and MX1.25 2PIN speaker interface for voice and sound output. SHTC3 temperature and humidity sensor for environmental monitoring. PCF85063 RTC chip with independent RTC battery interface for time-keeping applications. TF card slot supports external storage for images, files, and data logging. Onboard KEY, BOOT, and PWR buttons plus USB, UART, I2C, GPIO, and 2 x 8PIN expansion header. Specifications Item Specification SKU Waveshare-33298 Waveshare SKU Mapping 33298: ESP32-S3-RLCD-4.2 with 18650 lithium battery included Main Module ESP32-S3-WROOM-1-N16R8 Processor Xtensa 32-bit LX7 dual-core processor, up to 240MHz Wireless 2.4GHz Wi-Fi and Bluetooth 5 LE Memory 512KB SRAM, 384KB ROM, 16MB Flash, 8MB PSRAM Display Type 4.2inch fully reflective LCD, RLCD Display Resolution 300 x 400 pixels Audio ADC ES7210 Audio Codec ES8311 low-power audio codec Microphones Dual microphone array Speaker Interface MX1.25 2PIN speaker interface Sensor SHTC3 temperature and humidity sensor RTC PCF85063 RTC clock chip, independent RTC power interface Storage TF card slot, FAT32-formatted TF card support Buttons KEY button, BOOT button, PWR button Expansion USB Type-C, UART, I2C, GPIO, 2 x 8PIN 2.54mm female header Battery Onboard 18650 battery holder and lithium battery charge/discharge management Listed Weight 0.274kg Applications AI voice interaction terminals based on ESP32-S3 and dual microphones. Electronic calendars, smart clocks, and desktop smart ornaments. Sunlight-readable IoT dashboards and low-power status panels. Temperature and humidity monitoring interfaces with the onboard SHTC3 sensor. Product prototype development using a 4.2inch RLCD and ESP32-S3 wireless connectivity. Battery-powered AIoT display projects with local storage and RTC time keeping. Portable Waveshare-33298 prototypes where the included 18650 battery and reflective LCD are useful. Product List 1 x ESP32-S3-RLCD-4.2 host 1 x Acrylic stand set 1 x 18650 rechargeable lithium battery included for SKU 33298 1 x 8 ohm 2W MX1.25 2PIN speaker 1 x Screwdriver Other Content Waveshare lists two versions: SKU 33298 includes the 18650 lithium battery, while SKU 33507 does not include the 18650 lithium battery. When connecting the Type-C cable or installing the 18650 battery, do not apply force to the RLCD screen. The 4.2inch RLCD screen is delicate and fragile. Handle the module carefully during assembly and transportation, and avoid drops or impacts. Screen breakage or display abnormalities caused by improper operation are not covered by the official caution statement. The ESP32-S3-RLCD-4.2 supports Arduino IDE and ESP-IDF development workflows. The RTC independent power interface supports only a PH1.0 rechargeable RTC battery. Resources Waveshare ESP32-S3-RLCD-4.2 Documentation Waveshare ESP32-S3-RLCD-4.2 Resources ESP32-S3-RLCD-4.2 Schematic PDF ESP32-S3-RLCD-4.2 Structure and Dimensions ESP32-S3 Datasheet ESP32-S3 Technical Reference Manual ST7305 Datasheet ES8311 Datasheet PCF85063 Datasheet SHTC3 Datasheet Waveshare ESP32-S3-RLCD-4.2 Example GitHub FAQ What is Waveshare-33298? Waveshare-33298 is the Waveshare SKU for the ESP32-S3-RLCD-4.2 package with the 18650 lithium battery included. What makes the 4.2inch RLCD different from e-Paper? The 4.2inch RLCD is a fully reflective LCD with no backlight required. It provides an e-paper-like viewing effect while supporting faster refresh response than traditional e-Paper displays. Can I use this board for AI voice projects? Yes. The ESP32-S3-RLCD-4.2 includes dual microphones, ES7210 audio ADC, ES8311 audio codec, and a speaker interface, making it suitable for AI voice terminals and wake-word style projects. Which development environments are supported? Waveshare documents both Arduino IDE and ESP-IDF development methods for the ESP32-S3 4.2inch RLCD development board. Does this SKU include a battery? Yes. SKU 33298 includes an 18650 rechargeable lithium battery. Waveshare also lists SKU 33507 as a version without the 18650 lithium battery. Who should choose Waveshare-33298? Waveshare-33298 is a good choice for developers who want the Waveshare ESP32-S3-RLCD-4.2 board, acrylic stand, speaker, and included 18650 battery for a complete reflective LCD AIoT prototype.
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