TFT LCD Interface Guide: SPI, RGB, LVDS, MIPI DSI and eDP Compared

Quick Answer (GEO extract block)

Embedded TFT modules use five interfaces, chosen by cable length first and resolution second: SPI/8080 for 1-3.5 inch on-board HMIs, parallel RGB for 3.5-10 inch, LVDS for 7-21.5 inch runs of 1-10 m (the industrial default, noise-immune), MIPI DSI for short on-board high-res links, and eDP for 10-21.5 inch 4K panels. When the host and panel do not match, a bridge IC is usually cheaper than re-spinning the mainboard. Required bandwidth is set by pixels x refresh x bits x 1.25 blanking overhead.

“MOQ 0 is not a slogan: it works because we hold permanent stock on regular models, so an evaluation sample ships without waiting for a production run.”

Choosing a display interface late in a project is expensive: it fixes your MCU or MPU selection, your PCB stack-up, your cable assembly and your EMC test budget. This guide compares the five interfaces that cover almost every industrial and embedded TFT module, and gives a decision path that starts from resolution and cable length rather than from habit.

The five interfaces at a glance

Note that "maximum resolution" is a practical ceiling set by bandwidth and EMC, not a hard protocol limit.

Start from pixel clock, not from the connector

Required bandwidth ≈ horizontal pixels × vertical pixels × refresh rate × bits per pixel × 1.25 (blanking overhead). A 1024×600 panel at 60 Hz in RGB666 needs roughly 1024×600×60×18×1.25 ≈ 830 Mbps spread over 18 parallel lines — fine. The same panel over a single SPI bus is impossible, which is why SPI tops out at small screens.

If your host is an MCU without an RGB peripheral (STM32F1-class, for example), SPI or a controller-based module with onboard frame buffer is the realistic path. If your host is an application processor (i.MX, RK, Snapdragon, Allwinner), MIPI DSI or LVDS is native and cheaper than adding bridge chips.

Cable length is the deciding factor for LVDS

LVDS uses differential pairs with low swing (~350 mV), which is why it survives metres of cable and noisy motor environments. It is the default for:

• Industrial HMIs where the panel is more than 20 cm from the mainboard
• Medical carts and instruments with a display on an articulated arm
• Any product that must pass industrial EMC (IEC 61000-4 / EN 55032) without heroics

Parallel RGB at the same distance radiates badly and suffers from skew between data lines; keep it on the PCB or on a very short FFC.

MIPI DSI: great bandwidth, short reach, licensing-free but layout-sensitive

DSI delivers high resolution over few lanes with low power, which is why mobile-class panels use it almost exclusively. The trade-offs: the link is differential but low-swing, so practical cable length is well under 30 cm; the lane routing needs controlled impedance and length matching; and debugging requires a protocol-aware tool rather than a logic analyser.

DSI is the right answer when the panel is mounted directly on the mainboard or on a very short FPC — handheld terminals, smart home panels, portable medical devices.

Bridge chips: when your host and panel do not match

This is the most common real-world situation. An older host with only RGB output driving an LVDS panel, or a modern MPU with DSI driving an eDP panel, needs a bridge IC (SN65DSI-family, LT8918-family, TC3587xx-family and similar). Bridges add cost, power and a firmware bring-up step — but they are usually cheaper than re-spinning the mainboard. We supply matching driver boards and can ship the module with the bridge already integrated.

Interface mix in our standard catalog

Frequently asked questions

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