1.4 inch Square Display Screen ST7789 SPI

I. Product Overview

HOTHMI introduces the HTM-H014A3-SPI-V0, a high-quality 1.4-inch TFT Square Display Screen module. This model incorporates the ST7789 driver IC and delivers a standard resolution of 240×3RGB×240, with full Full O’Clock wide viewing angle support for excellent color reproduction and visual clarity from any direction. The mechanical design is extremely compact: the TFT panel outer dimension measures only 27.56mm × 30.70mm, while the active display area is a perfect 25.20mm × 25.20mm square.

In terms of electrical performance, the operating voltage ranges from 2.6V to 3.3V. The built-in drive circuit supports flexible 3-wire and 4-wire SPI interfaces via a standard 8-pin signal connector. Typical luminance of this Square Display Screen is 400 cd/m², and the operating temperature covers -20℃ to +70℃ (storage temperature from -30℃ to +80℃), making it suitable for diverse industrial, commercial, and custom applications that demand reliability under harsh conditions. With its sturdy square form factor, full-angle clarity, and industrial-grade thermal tolerance, this module has become a preferred choice for smart hardware, handheld devices, and embedded control systems.

II. Key Features & Highlights

Engineered for high-standard industrial and commercial use, the HTM-H014A3-SPI-V0 Square Display Screen offers the following notable technical advantages:

• Full O’Clock wide viewing angle technology: advanced panel processing delivers 80° viewing angles in all directions. No matter from which angle users view this Square Display Screen, images remain free from distortion, color shift, or inversion.
• Industrial-grade wide temperature design: specifically optimized for challenging environments, with an operating range of -20℃ to +70℃ and storage range of -30℃ to +80℃, ensuring stable performance in outdoor or factory-floor conditions.
• High-speed serial SPI interface: compatible with both 3-wire and 4-wire SPI modes. Compared with traditional parallel buses, the SPI interface significantly reduces wiring complexity, enables more compact PCB layouts, and works seamlessly with mainstream microcontrollers such as Arduino, ESP32, STM32, and Raspberry Pi.
• Constant-current high-brightness backlight: equipped with an efficient constant-current LED driver, delivering 400 cd/m² of uniform luminance. This not only ensures stable light output but also extends the operational lifespan of the Square Display Screen and minimizes heat generation.

III. Pin Description

This Square Display Screen provides 8 essential signal pins through its pin-header interface.

IV. Applications

Thanks to its unique 1:1 square aspect ratio, standard resolution, full viewing angles, and robust environmental adaptability, this 1.4-inch Square Display Screen is widely adopted in the following fields:

• Smart wearables and health monitoring: the symmetric 240×240 display characteristics make it ideal for smartwatches, fitness bands, portable oximeters, and heart rate monitors, delivering well-proportioned and detailed UI animations.
• Industrial control and instrumentation: in demanding factory environments, the wide-temperature range ensures stable operation under extreme cold or heat. It is commonly used in digital multimeters, handheld laser rangefinders, and industrial sensor HMI panels.
• Smart home and IoT nodes: can be embedded into smart thermostats, gateway status panels, round or square smart switch panels, serving as a compact data display terminal.
• Consumer electronics and creative DIY: within the maker community, mature open-source libraries for ST7789 (such as Adafruit_GFX and LVGL) make this Square Display Screen a popular choice for mini retro game consoles, desktop “spaceman” mini TVs, serial debug monitors, and other creative projects.

V. Technical FAQ 

Q1: Can the HTM-H014A3-SPI-V0 be directly connected to a 5V microcontroller (e.g., traditional Arduino Uno)?

A1: No, direct connection is not recommended. The VCI operating voltage and I/O logic levels of this Square Display Screen module are rated at 2.6V ~ 3.3V. Traditional 5V microcontrollers like Arduino Uno output 5V high-level logic, which can easily damage the input pins of the ST7789 driver IC. If you are using a 5V microcontroller, you must add level-shifting components (such as a 74HC4050) or resistor divider networks on signal lines including SCK, SDA, CS, D/C, and RESX to reduce the logic level to 3.3V for safe operation. For native 3.3V controllers like ESP32 or STM32, direct connection is supported.

Q2: How can I adjust the brightness of this Square Display Screen via the BLEN pin?

A2: The BLEN pin on this module supports not only on/off switching but also PWM (Pulse Width Modulation) signal input. You can connect a GPIO pin with PWM output capability from your microcontroller to the BLEN pin. By varying the PWM duty cycle in your code, you can smoothly regulate the backlight LED current, achieving 0% to 100% stepless brightness adjustment for the Square Display Screen. This feature is particularly useful for developing night modes or power-saving operation.

From minor concept tweaks to full custom redesign & development, our engineering team offers end-to-end technical support. Feel free to contact us for custom display demands or technical issues during product selection.