Hardware Overview

This section focuses on the appearance and structure of reTerminal Sticky, its core hardware modules, and the internal hardware architecture of the device.

Appearance & Structure

Sticky uses a card-style form factor with a glass touch front panel. Internally, the layout is built around the main board, battery, and display module in a slim design.

Structural Highlights

Multiple N52 magnets are built into the four corners for attachment to metal surfaces
The front side uses a glass touch cover panel
The bottom side includes a Reset hole, microphone opening, and lanyard hole
The charging indicator is located on the left side of the USB-C port
An adhesive magnetic ring is supported for installation on non-metal surfaces

Quick Specs

Item	Details	Notes
Dimensions	106mm x 65.5mm x 7.3mm	Compact card-style structure
Weight	70g	Easy to mount and use day to day
Protection	IP40	Not waterproof

Core Hardware Modules

Main Controller & Storage

Item	Details	Notes
Main controller	ESP32-S3R8, 8 MB PSRAM	Core system control unit
External Flash	256 Mbit QSPI Flash	External SPI storage for firmware and data
Expandable storage	MicroSD	Connected to the main controller through SPI/SD signals

The main control system of Sticky is built around the ESP32-S3R8, which handles display control, touch interaction, sensor scheduling, wireless communication, and local storage management.

Display Module

Item	Details	Notes
Display type	Black-and-white E-Ink display	Suitable for long-duration display
Display size	3.97 inches	Card-style viewing area
Resolution	800 x 480	Suitable for text and lightweight graphics
Pixel density	235 ppi	Clearer text and image rendering
Grayscale	4-level grayscale	Supports basic grayscale content
Touch	Capacitive touch panel	Supports basic on-device interaction

The display module is one of Sticky’s core hardware capabilities. It combines an E-Ink display with capacitive touch to support long-term information display and basic interaction in low-power scenarios.

Sensors & Input

Item	Details	Notes
Temperature and humidity sensor	Built-in	Ambient temperature and humidity detection
IMU	6-axis IMU	Motion and orientation detection
RTC	External real-time clock	System time keeping
Microphone	PDM digital microphone	Voice capture
Physical buttons	3	Local input
Buzzer	1	Interaction prompt
Reset	Reset button hole	Device reset

The sensors and input section provides environmental sensing, motion detection, voice input, and basic interaction feedback, giving the system the key inputs and status signals it needs.

Connectivity & Interface

Item	Details	Notes
Wi-Fi	2.4GHz	Device connectivity and OTA
Bluetooth	BLE 5.0	Provisioning and short-range connection
USB port	USB-C	Power, data communication, and firmware download

Sticky supports both wireless and wired connectivity for networking, short-range pairing, power input, and data transfer.

Power System

Item	Details	Notes
Battery	750mAh single-cell lithium battery	Device power supply
Charging port	USB-C	Standard charging
Charging indicator	Dual-color indicator (red/green)	Charging status indication

Sticky supports both USB-C power input and battery power, making it better suited for low-frequency updates and always-on display scenarios.

Hardware Diagram

Architecture Overview

The hardware system of reTerminal Sticky is centered on the ESP32-S3. With 8 MB of integrated PSRAM, this main controller coordinates the display, touch input, sensors, wireless connectivity, audio input, and local storage across the device.

Around the main controller, the Sticky hardware system can be understood as the following subsystems:

Display and touch
The 3.97-inch E-Ink display connects to the main controller through the SPI interface and is used to present text, icons, and other lightweight visual content. The touch panel connects through I2C and provides local touch input. With an 800 x 480 resolution and 4-level grayscale, the display system is well suited to low-power always-on use cases such as information boards, to-do lists, and status displays.
Storage system
The device includes 256 Mbit of QSPI Flash for firmware storage and local data caching. It also supports MicroSD expansion through the SPI interface, providing additional local storage capacity when needed.
Sensors and clock
The 6-axis IMU, temperature and humidity sensor, and RTC are connected to the main controller through I2C. Together, they support orientation detection, environmental sensing, and time keeping. These devices provide the hardware foundation for automatic screen rotation, information refresh logic, and scheduled tasks.
Audio and local interaction
Sticky includes a built-in PDM microphone for voice input and a buzzer for basic audio prompts. The AI button, Up button, Down button, and Reset button form the main local input path on the device.
Wireless communication system
Sticky integrates both 2.4GHz Wi-Fi and BLE 5.0. Wi-Fi is used mainly for device networking, content synchronization, and OTA updates, while BLE is used mainly for provisioning, pairing, and short-range connection. Both are managed by the wireless subsystem inside the ESP32-S3.
Power and debug path
The USB-C interface is used for external power input, data transfer, and device debugging. The power management circuitry coordinates USB power and battery power, while the built-in 750mAh battery supports long-duration operation in low-power E-Ink usage scenarios.

Overall, Sticky’s hardware architecture is built around low power consumption, long-duration operation, lightweight interaction, and wireless connectivity. With the ESP32-S3 as the central controller, the device brings together display, touch, sensing, audio input, storage, and connectivity through standard interfaces such as SPI, I2C, and GPIO, enabling stable operation across typical information display and light interaction use cases.