Battery-powered knob display board pairs ESP32-S3 and ESP32 wireless SoCs, features audio DAC for audio visualization

The Waveshare ESP32-S3-Knob-Touch-LCD-1.8 is a batterry-powered knob display board designed for HMI applications that combines ESP32-S3 and ESP32 SoCs in a dual MCU architecture. The design differs from other ESP32-based knob / rotary encoder with a built-in display such as the MaTouch SmartKnob, M5Dial, and LILYGO T-Encoder Pro.

The Waveshare device also stands out with a larger 1.8-inch capacitive touch display, integrated audio DAC, and real-time audio visualization. It comes with a CNC-milled full-metal enclosure for a more premium and durable build. The devkit supports swipe gestures and volume control, and can be used as a Pomodoro timer, a text reader, a secondary PC screen, and a Bluetooth audio player through a 3.5mm audio jack. Other features include a digital microphone, a vibration motor, and a microSD card slot for storage.

ESP32-S3-Knob-Touch-LCD-1.8 Specifications:

MCUs
- Espressif ESP32-S3R8
  - CPU – Dual-core Tensilica LX7 microcontroller up to 240 MHz with vector instructions for AI acceleration
  - Memory – 8MB PSRAM
  - Wireless – WiFi 4 and Bluetooth 5.0 LE + Mesh connectivity
- Espressif ESP32-U4WDH
  - Dual-core Xtensa LX6 microcontroller up to 240 MHz
  - Memory – 4MB embedded Flash
  - Wireless – Wi-Fi 4 and Classic Bluetooth (no BLE support)
Storage – 16MB SPI flash, MicroSD card socket
Display
- 1.8-inch IPS LCD panel with touchscreen via CST816 chip
- Resolution – 360×360 pixels
- 262K colors, 600cd/m² brightness, 1200:1 contrast
- QSPI interface, driven by ST77916 controller
Connectivity
- 2.4GHz Wi-Fi 802.11 b/g/n
- Bluetooth 5 LE + Classic
- Onboard ceramic antenna for both ESPs
Audio
- PCM5100A I2S DAC for stereo audio output
- Digital MEMS microphone for real-time audio spectrum visualization
- 3.5mm audio jack (external speaker required)
USB – USB-C port for power and programming
Misc
- Dual encoder for ESP32-S3 and ESP32
- Vibration motor (DRV2605 driver over I²C)
- Power button
- ESP32-S3R8 boot button
- CH445P 4-SPDT analog switch IC
- PH1.27 10P SMD connector and headers
Power Supply
- 5V from USB-C port
- PH1.25 lithium battery connector (optional 3.7V 102035 800mAh battery)
- Onboard battery charger
Dimensions – 66 x 22 mm
Enclosure – CNC-machined metal case

In terms of software, the device board can be programmed using both the Arduino IDE and ESP-IDF, with example code and setup instructions available on Waveshare’s wiki page. The board uses LVGL for building a responsive touch-based GUI and integrates smoothly with USB CDC, UART, I2C, SPI, and BLE APIs thanks to the ESP-IDF SDK.

Besides its ESP32-S3 + ESP32 design, what is most interesting about this knob display board is the implementation of the CH445P 4-SPDT analog switch IC; with this, Waveshare is using a single USB to program both the onboard ESP32s. Speaking of dual onboard ESP32s, the company doesn’t mention which ESP is programmed to do what. If I had to assume. The ESP32-S3R8 is the primary MCU who handles main application logic, GUI rendering, touchscreen and rotary knob input, audio spectrum visualization, and communication. It also interfaces with peripherals like the SD card, display, I2C, and SPI devices. The ESP32 would then take care of other low-level I/Os. However, a quick look at the schematics reveals that the ESP32 is used for USB UART, and both the ESP32 and ESP32-S3 have signals connected to the audio DAC…

The ESP32-S3-Knob-Touch-LCD-1.8 ships with the device itself and its back cover. You can purchase it on AliExpress for $48.75, on Amazon for $52.99 (with or without battery), and on the Waveshare store for $46.99. The exact price will depend on taxes and shipping to your country.

Debashis Das

Debashis Das is a technical content writer and embedded engineer with over five years of experience in the industry. With expertise in Embedded C, PCB Design, and SEO optimization, he effectively blends difficult technical topics with clear communication