The ESP32-S3-RLCD-4.2 is a powerful AIoT development board built around the ESP32-S3, combining a low-power 4.2-inch reflective LCD with wireless connectivity, audio, sensors, and expandable interfaces.
Its 300 × 400 reflective display does not require a backlight and uses ambient light for visibility, providing an e-paper-like reading experience while offering faster refresh rates.
Key Features
- ESP32-S3 dual-core processor up to 240 MHz
- 16 MB Flash + 8 MB PSRAM
- 2.4 GHz Wi-Fi and Bluetooth 5 LE
- 4.2-inch reflective LCD
- 300 × 400 resolution
- Black-and-white display with no backlight
- Built-in SHTC3 temperature and humidity sensor
- Real-time clock (RTC) with PCF85063
- Dual microphone array with echo-cancellation support
- Built-in ES8311 audio codec
- Speaker connector
- TF/microSD card slot for external storage
- 18650 battery holder with charging and power management
- Programmable KEY and BOOT buttons
- USB Type-C for programming and serial logging
- UART, I²C and GPIO interfaces for expansion
- 2 × 8-pin expansion header with 2.54 mm pitch
Ideal for R1BBIT
The board is particularly suitable for projects requiring a large low-power display, sensors, wireless connectivity, and audio in a single device. It can be used for smart dashboards, electronic calendars, environmental monitors, AI assistants, IoT controllers, and interactive desktop devices.
With R1BBIT, the ESP32-S3-RLCD-4.2 can become an accessible platform for creating these projects without requiring complex low-level programming.
CONFIG
// ── Display: reflective 4.2" ST7305, 400x300 ──
DISPLAY_DRIVER ST7305
SPI_MOSI 12
SPI_CLK 11
SPI_FREQ 20000000
DISPLAY_CS 40
DISPLAY_DC 5
DISPLAY_RST 41
DISPLAY_W 400
DISPLAY_H 300
// ── I2C0: ES8311 0x18, ES7210 0x40, PCF85063 0x51, SHTC3 0x70 ──
I2C_SDA 13
I2C_SCL 14
I2C_FREQ 400000
// ── SD card: SDMMC, 1-bit data mode ──
SD_BUS MMC
SDMMC_WIDTH 1
SDMMC_CLK 38
SDMMC_CMD 21
SDMMC_D0 39
// ── Audio: ES8311 codec, speaker through built-in amplifier ──
CODEC ES8311
CODEC_ADDR 0x18
CODEC_PA_PIN 46
AUDIO_OUT CODEC
AUDIO_IN CODEC
I2S_MCLK 16
I2S_BCLK 9
I2S_WS 45
I2S_DOUT 8
I2S_DIN 10
I2S_FREQ 16000
CODEC_PA_ACTIVE_LOW 0
// ── Buttons and battery ──
IN1 18 KEY
IN1_PULL UP
IN2 0 BOOT
IN2_PULL UP
ADC_IN1 4 VBAT
ADC_IN1_ATTEN 11
TIMEZONE 0
UNITS IMPERIAL
END_CONFIG
// Variables for the SHTC3 sensor
VAR temp
VAR hum
// Initialize the sensor (updates temp and hum every 2 seconds)
SHTC3_INIT(temp, hum, 200)
DISPLAY_INIT
WHILE 1
PAUSE 1000
WEND
