HOTHMI 2.8 inch TFT Display 320×240 USART ST7789

Product Introduction

The HTM-H028A16-USART-ST is a 2.8 inch TFT Display module designed for embedded devices and human-machine interface (HMI) terminals. It uses a 2.8-inch TFT LCD panel with a resolution of 320 × 240 RGB and a brightness of 500 cd/m². The display adopts a TFT, transmissive, Normally Black structure and supports 262K colors. With a Full View design, the module provides consistent readability when the interface is viewed from different directions.

Unlike a conventional solution that only provides a bare LCD panel, this 2.8 inch TFT Display integrates an ST-MCU + ST7789 driver solution and provides both a USART Serial interface (TTL/CMOS) and a USB to USART interface. This reduces some of the hardware and software work normally required to drive a TFT LCD directly from the host controller. For equipment based on MCUs, embedded controllers, or serial communication architectures, engineers can use USART communication to exchange data with the display module and control the user interface.

The module operates at a typical supply voltage of 5.0V and supports an operating temperature range from -30°C to +80°C. This temperature range makes the 2.8 inch TFT Display suitable for industrial equipment, control terminals, and selected embedded products used in outdoor or temperature-variable environments.

From a mechanical design perspective, the PCB outline is approximately 88.00 × 53.30 mm. The active display area is approximately 57.60 × 43.20 mm, while the frame size is approximately 70.20 × 51.00 mm. Four mounting holes are provided, so the hole positions and edge dimensions shown in the mechanical drawing should be considered when designing the enclosure or mounting bracket. The maximum component height on the PCB is 6.00 mm, meaning sufficient Z-direction clearance should be reserved around the module when designing the housing, front frame, and mounting structure.

Product Specifications

2.8 inch TFT Display Highlights

320 × 240 RGB Resolution

The 2.8 inch TFT Display provides a 320 × 240 RGB resolution, which is suitable for displaying operating parameters, menus, status information, icons, numerical values, and basic graphical interfaces on a compact screen.

For small embedded products, this resolution provides enough display space for practical HMI layouts while keeping the overall module size relatively compact.

Full View Display

The module features a Full View display structure with a specified viewing direction of U80/D80/L80/R80. This is useful for equipment where the display may be installed horizontally, vertically, or at an angle.The wide viewing characteristics of this 2.8 inch TFT Display can also make interface information easier to read when the operator is not directly in front of the screen.

USART TTL/CMOS Interface

The 2.8 inch TFT Display module provides a USART Serial interface with CMOS 0/3.3V signal levels. When connecting the display to a host MCU, engineers should verify the UART voltage level and signal definition of the host system before hardware integration.The serial interface allows the host controller to communicate with the display module without requiring the host MCU to directly manage the TFT LCD interface.

USB to USART for Development and Firmware Upgrade

In addition to the USART interface, the module provides a USB to USART interface and supports Firmware Upgrade.This interface can be useful during product development, debugging, software testing, and firmware update procedures, providing engineers with a more convenient way to communicate with the display system during development.

Wide Operating Temperature Range

The module supports an operating temperature range of -30°C to +80°C. This allows the 2.8 inch TFT Display to be considered for industrial control equipment and embedded products that may operate under changing ambient temperatures.The actual suitability for a specific application should be evaluated together with the thermal conditions of the complete system.

External Button Signal Input

The J5 interface provides multiple PC/PD signals identified as Button Signal Input. These signals can be connected to external mechanical buttons, providing a hardware input option for HMI products that do not require a touchscreen.This configuration is useful for functions such as menu navigation, parameter adjustment, selection, confirmation, and basic equipment control.

Pin Description

J3 – USART Interface

J4 – USB Interface

J5 – External Button / Firmware Upgrade

Product Applications

The compact size and serial communication architecture make the HTM-H028A16-USART-ST a practical 2.8 inch TFT Display solution for embedded HMI applications where a small screen and physical controls are preferred.

Industrial Controllers

The 2.8 inch TFT Display can be used in compact industrial controllers for status monitoring and parameter adjustment. For example, in motor controllers, pump controllers, or equipment control units, the host controller can send operating data through USART and display running status, set values, actual values, alarm information, and operating modes on the screen.

External buttons connected through J5 can be assigned to menu navigation, parameter adjustment, and confirmation functions, making this 2.8 inch TFT Display suitable for industrial equipment that does not require a touchscreen.

Portable Test Instruments

This 2.8 inch TFT Display can be integrated into portable electrical testers, inspection instruments, and measurement devices. The 320 × 240 RGB resolution provides sufficient space for measurement values, units, test status, and operating prompts.

The host controller can update the displayed information through USART, while the compact 2.8-inch form factor helps manufacturers maintain a relatively small enclosure for handheld equipment.

Compact Equipment HMI

For automation equipment, small dedicated machines, and embedded control systems, the module can serve as an independent HMI display unit.

The main controller can send operating data through USART to display equipment status, operating modes, parameter settings, and fault messages. Button Signal Input through the J5 interface can be used for start, stop, menu selection, parameter modification, and confirmation functions.

Instrument Control Panels

The HTM-H028A16-USART-ST is also suitable for instrument control panels that require numerical information and physical button operation. Typical interface content can include real-time values, measurement units, operating status, and alarm notifications.

The USART interface handles communication between the display and control system, while the Full View design supports U80/D80/L80/R80 viewing directions. This can be useful when the display installation angle is restricted by the equipment structure.

Technical FAQ

Q1. How should the USART TX and RX pins be connected to the host MCU?

For a standard UART connection, the host MCU TX should be connected to the display’s USART_RX, while the host MCU RX should be connected to the display’s USART_TX. The GND of the host controller and display module should also be connected to establish a common reference.

The J3 interface provides the dedicated USART_TX and USART_RX signals, both specified as CMOS 0/3.3V levels. Engineers should confirm the actual signal definition and electrical requirements in the product documentation before final PCB design.

Q2. What should engineers consider when designing the mechanical structure?

The PCB outline is approximately 88.00 × 53.30 mm, with four Ø3.00 mm mounting holes. The mechanical drawing also specifies a maximum component height of 6.00 mm.

When integrating the 2.8 inch TFT Display into an enclosure, engineers should consider the PCB outline, active area, mounting-hole positions, connector locations, frame dimensions, and Z-direction clearance. These dimensions should be checked against the final mechanical drawing before tooling or mass production.