Small-Size Industrial LCD Screens: What are the Differences Between MIPI and SPI Interfaces?

In small-size industrial LCD screen applications, choosing the right interface has a crucial impact on system performance, cost, and reliability. MIPI and SPI are two common interface types, each with different characteristics and applicable scenarios. This article will discuss in detail the differences between MIPI and SPI interfaces in small-size industrial LCD screens to help engineers and developers make better interface selections.

Differences between MIPI and SPI Interfaces

Bandwidth and Performance

MIPI: The MIPI DSI interface boasts very high bandwidth, typically measured in Gbps. For example, a common 4-lane configuration with 1.5Gbps per lane can theoretically achieve a throughput of 6Gbps. This allows MIPI to easily support the demands of high-resolution, high-refresh-rate displays.

SPI: The SPI interface has relatively lower bandwidth, typically ranging from tens of MHz to tens of Mbps. For example, some SPI master controllers can achieve data rates of up to 33Mb/s, but in practical applications, it is often subject to more limitations. For high-resolution or high-refresh-rate applications, SPI may fall short.

Hardware Complexity and Cost

MIPI: The MIPI interface requires more complex hardware design, including high-speed differential signal routing and stringent PCB design specifications. This increases the difficulty and cost of hardware design.

SPI: The SPI interface has simple hardware connections, typically requiring only four wires (clock line, data line, chip select line, etc.), resulting in lower hardware costs and making it suitable for cost-sensitive applications.

Signal Integrity and Interference Resistance

MIPI: The MIPI interface uses differential signal transmission, providing strong interference resistance and making it suitable for industrial applications in complex electromagnetic environments.

SPI: The SPI interface has low requirements for wiring at low speeds, but is susceptible to electromagnetic interference at high speeds, leading to signal instability.

Display Effects and Application Scenarios

MIPI: Suitable for scenarios with high resolution, high refresh rates, and many dynamic graphics, such as high-definition displays in industrial monitoring systems.

SPI: More suitable for scenarios with low resolution, low refresh rates, and primarily static UIs, such as simple industrial instruments and sensor display terminals.

Frequently Asked Questions(FAQ)

Will SPI always cause lag on small-sized industrial LCD screens?

Not necessarily. The bottleneck of SPI is mainly bandwidth. If the application is low-resolution, low-refresh-rate, and primarily uses a static UI, the experience can be very smooth by using partial refresh, DMA, and reducing the full-screen refresh rate.

How to choose between Video Mode and Command Mode for MIPI DSI?

If a consistently high frame rate and stable video streaming are required, Video Mode is usually preferred. If it’s more about interface interaction and partial updates, and you want to reduce unnecessary full-screen streaming and power consumption, Command Mode is more common.

Why are MIPI screens more prone to screen flickering, white screens, and occasional glitches?

MIPI screens’ high-speed differential links are more sensitive to traces, impedance, length matching, and connector and cable quality. When the speed increases or the cable length increases, the signal margin is compressed, and occasional bit errors will manifest as screen flickering or glitches.

conclusion

In small-size industrial LCD screen applications, both MIPI and SPI interfaces have their advantages. If the application requires high resolution, high refresh rate, and dynamic graphics display, MIPI is a better choice; if the application is cost-sensitive and primarily uses static UI displays, SPI is more suitable. When choosing an interface, a comprehensive consideration should be given to specific application requirements, system costs, and hardware design capabilities.