Why ESP32 Usually Chooses SPI Interface TFT LCD Displays

The ESP32 has emerged as one of the most widely used microcontrollers in the Internet of Things (IoT) and embedded systems landscape. Its powerful dual-core processor, integrated Wi-Fi and Bluetooth connectivity, and support for various interfaces make it highly versatile. Among the many peripherals developers pair with the ESP32, TFT LCD displays stand out as one of the most common. Interestingly, most ESP32-based projects and products rely on SPI (Serial Peripheral Interface) TFT LCDs instead of other display interfaces like MIPI DSI or parallel connections. This preference is not coincidental; it is rooted in technical efficiency, cost-effectiveness, and compatibility.

Understanding SPI TFT LCD Displays

An SPI TFT LCD display uses the Serial Peripheral Interface protocol to communicate with the host microcontroller. Unlike parallel displays that use multiple data lines to transmit information simultaneously, SPI sends data serially over fewer pins. Typical SPI TFT modules require only four or five connections (MISO, MOSI, SCLK, CS, plus optional DC/Reset), which simplifies wiring and integration.

This streamlined communication method makes SPI TFTs particularly suitable for microcontrollers like the ESP32, which often operate in compact, resource-constrained environments.

Reasons ESP32 Commonly Uses SPI TFT LCD Displays

1. Pin Efficiency and Hardware Compatibility

The ESP32 has multiple GPIO pins, but many are reserved for Wi-Fi, Bluetooth, or specific functions. When developers design IoT devices, they need to balance sensor inputs, actuators, and communication lines. SPI requires significantly fewer pins compared to an 8-bit or 16-bit parallel TFT interface. This allows designers to connect more peripherals without running into pin conflicts.

Additionally, the ESP32 has hardware SPI controllers built-in, which ensures smooth, efficient communication with SPI TFT modules.

2. Speed Adequacy for Most Applications

While parallel interfaces can achieve higher data transfer speeds, the SPI bus is fast enough for most applications powered by the ESP32. SPI speeds of up to 40 MHz are common, which provides adequate frame rates for GUIs, dashboards, and real-time data displays. For IoT devices, where static or semi-dynamic information is shown (such as graphs, menus, or sensor data), SPI offers more than sufficient performance without adding complexity.

3. Lower Cost and Wide Availability

Another important factor is cost-effectiveness. SPI TFT LCD displays are widely produced, readily available in sizes ranging from 1.3 inches to 3.5 inches, and typically much cheaper than MIPI or LVDS displays. Since many ESP32 projects are aimed at consumer-grade products, DIY kits, or cost-sensitive IoT devices, choosing SPI TFTs makes financial sense.

Moreover, an enormous ecosystem of open-source libraries, such as TFT_eSPI for Arduino and PlatformIO, already exist to support these displays. This drastically reduces development time and cost.

4. Simplified PCB and Wiring Design

When designing compact devices, PCB layout becomes critical. Parallel TFT LCDs require multiple data lines (sometimes more than a dozen), which complicates routing and increases board size. In contrast, SPI requires only a few traces, leading to smaller, cheaper, and more reliable PCB designs.

For developers using breadboards or prototyping boards, SPI displays are also easier to wire and debug, which accelerates prototyping cycles. Trusted LCD manufacturers in China often optimize these SPI TFT modules for better compatibility and stability in embedded systems.

5. Power Efficiency

IoT devices powered by ESP32 are often battery-operated, making power efficiency a top priority. SPI TFT modules, being simpler and optimized for microcontrollers, consume less power compared to large high-speed parallel or MIPI-driven LCDs. Lower energy requirements extend battery life, which is essential for portable devices like handheld testers, wearables, or remote monitoring units.

6. Rich Ecosystem and Community Support

The popularity of ESP32 and SPI TFTs has created a vast ecosystem of tutorials, libraries, and community projects. Developers can find countless examples of integrating SPI displays with ESP32 for applications like weather stations, smart dashboards, gaming consoles, and industrial controls. This collective knowledge base reduces the learning curve and improves development efficiency.

Applications Benefiting from ESP32 + SPI TFTs

Smart home panels: IoT dashboards displaying sensor data, device controls, and automation status.

Portable test instruments: Handheld oscilloscopes, multimeters, and diagnostic tools.

Wearables: Fitness trackers and medical monitoring devices with small color screens.

Industrial controls: Compact HMIs (Human-Machine Interfaces) in machinery or factory equipment.

DIY and educational projects: Affordable and easy-to-use displays for learning embedded development.