Arduino and SPI Interface Display: A Perfect Match for Embedded Innovation

When it comes to developing embedded systems and DIY electronics, Arduino stands as one of the most popular and versatile platforms in the world. From hobbyists building small gadgets to engineers prototyping advanced IoT systems, Arduino offers an easy yet powerful way to connect sensors, actuators, and display modules. Among the various display communication methods, the SPI (Serial Peripheral Interface) has become a preferred choice for connecting TFT LCD displays and other visual interfaces to Arduino boards.

This article explores how SPI works with Arduino, why it’s so commonly used for display modules, and how this combination enables fast, efficient, and visually rich embedded designs.

Understanding the SPI Interface

SPI (Serial Peripheral Interface) is a synchronous serial communication protocol developed by Motorola in the 1980s. It’s widely used to connect microcontrollers to peripherals such as displays, memory chips, and sensors. Unlike asynchronous communication (like UART), SPI transfers data using a clock signal, ensuring fast and reliable data exchange between devices.

SPI uses four main signal lines:

MOSI (Master Out Slave In) – Sends data from the master (Arduino) to the slave (display).

MISO (Master In Slave Out) – Sends data from the slave to the master (not always used in displays).

SCLK (Serial Clock) – The clock signal generated by the master.

CS (Chip Select) – Used by the master to enable or disable specific slave devices.

Because SPI allows full-duplex data transfer and operates at relatively high speeds (up to several MHz), it is ideal for driving high-refresh-rate TFT LCDs and other displays that require smooth and responsive performance.

Why SPI Displays Are Popular with Arduino

1. Speed and Performance

Compared to I²C (Inter-Integrated Circuit), SPI offers significantly higher data transfer rates. This makes it well-suited for graphical displays, where large amounts of pixel data must be transferred rapidly. Arduino boards such as the Arduino Uno, Mega, or ESP32-based variants can easily drive SPI TFT displays with minimal lag, even for complex visual content.

2. Simplicity of Wiring

SPI connections are straightforward and require only a few wires between the Arduino and the display. For example, a typical 2.4-inch or 2.8-inch SPI TFT LCD might connect using just 5 to 7 pins. This simplicity helps reduce hardware complexity and makes wiring more manageable in compact designs.

3. Broad Library Support

One of Arduino’s biggest strengths is its rich ecosystem of libraries. SPI-based displays are supported by several well-maintained libraries, such as:

Adafruit GFX Library

TFT_eSPI Library (for ESP32/ESP8266)

UTFT and MCUFRIEND_kbv Libraries

These libraries simplify programming by providing pre-written functions for drawing shapes, displaying images, rendering fonts, and more—without requiring deep knowledge of low-level display commands.

4. Low Power Consumption

SPI displays often consume less power than their parallel-interface counterparts, making them suitable for battery-operated devices, portable instruments, and IoT nodes. The efficient data transfer mechanism of SPI ensures that only the necessary data is clocked through, saving both energy and processing time.

5. Compact Design Flexibility

Many small to medium-sized TFT LCDs (from 0.96-inch to 3.5-inch) are available with SPI interfaces, making them a perfect fit for compact embedded designs. Developers can integrate visual displays into even the smallest Arduino projects, such as handheld testers, wearable gadgets, or custom controllers.

Common SPI Display Types for Arduino

Arduino supports a wide range of SPI-based display modules, including:

TFT LCD Displays – Offering full-color graphical output, commonly using controllers like ST7735, ST7789, or ILI9341.

OLED Displays – Known for high contrast and deep blacks, often driven by SSD1306 or SH1106 controllers.

E-paper Displays – Low-power, sunlight-readable screens ideal for static content or battery-powered applications.

Touch Displays – SPI displays with capacitive or resistive touch layers, allowing user interaction through touch input.

Each type offers different benefits, but all share the same efficient SPI communication foundation.

Typical Applications of Arduino + SPI Display

The combination of Arduino and SPI displays has enabled countless practical applications across industries and projects:

Portable Monitoring Devices – Such as multimeters, environmental sensors, or medical monitors that require quick visual data feedback.

Smart Home Controllers – Wall-mounted or handheld panels showing temperature, humidity, and system status.

IoT Dashboards – Displaying live data from connected sensors or cloud platforms.

Wearable Electronics– Small SPI OLEDs or TFTs used in wristbands or health trackers.

3D Printers and CNC Machines – Control screens showing progress, parameters, and real-time status.

Educational and Hobby Projects – Ideal for teaching graphics programming and human-machine interface (HMI) design.

Example: Connecting a 1.8" SPI TFT to Arduino

A 1.8-inch SPI TFT display (ST7735 controller) typically connects to the Arduino as follows:

VCC → 5V or 3.3V

GND → GND

CS → D10

RESET → D9

DC/RS → D8

SDI(MOSI) → D11

SCK → D13

Using the Adafruit GFX and Adafruit ST7735 libraries, you can initialize the display in just a few lines of code and start drawing text, shapes, or images.

This simplicity, combined with high performance, is a major reason why SPI remains a top choice for Arduino-based display projects.

Challenges and Considerations

While SPI offers many advantages, there are a few trade-offs to consider:

Pin usage: Although fewer than parallel interfaces, SPI still occupies several dedicated pins, which may limit expansion options.

Shared bus management: When multiple SPI devices are connected, careful handling of the Chip Select (CS) lines is needed to prevent conflicts.

Speed limitations: The achievable SPI clock speed may vary depending on the Arduino board and wiring length.

However, with proper design and wiring, these issues are minimal and can be easily managed.

The Future of SPI Displays in Embedded Design

As displays become more essential in IoT and embedded systems, SPI remains a reliable and scalable communication method. With new microcontrollers offering faster SPI clock speeds and DMA (Direct Memory Access) capabilities, developers can achieve smoother animations and more complex graphical interfaces even on low-cost hardware.

Moreover, as libraries evolve to support frame buffering and hardware-accelerated rendering, SPI-based Arduino displays are closing the gap with higher-end graphical systems. The ongoing support from both open-source communities and display manufacturers ensures that SPI displays will continue to be a central component in embedded visualization.