LCD Interfaces Explained: SPI, MCU, RGB, LVDS and MIPI

The interface is the first decision, not the last: it decides whether your processor can drive the panel at all, how many pins the display costs you and whether you need a bridge IC. Rough rule: SPI up to about 320x240, 8-bit MCU up to about 480x272, RGB and LVDS for anything larger with a display controller in the host, MIPI for high resolution on a modern SoC, and a UART smart module when the host has no display capability at all.

Written by the Junxian applications engineering team. Figures quoted for “our models” are calculated from the 103 models on this site that carry a full parameter set, so they change when the catalogue changes.

How do I know which interface my processor supports?

Look for an LCD or display controller block in the processor datasheet. If it has one, it will name what it drives - RGB (sometimes called DPI or parallel), LVDS or MIPI DSI - and you should use that. If it has none, you are choosing between a serial-driven small panel (SPI or 8-bit MCU, where the panel's own driver IC holds the frame buffer) and a smart module that takes commands over UART. Adding an external bridge IC to give a controller-less MCU an RGB panel works, but it adds cost, board area and one more part to keep in supply.

SPI: fewest pins, lowest bandwidth

Four to five wires, the panel's driver IC stores the image, the host only sends changes. That makes SPI ideal for battery devices and pin-starved MCUs, and it is why almost every small round and square panel offers it. The limit is bandwidth: a full redraw of a 320x240 16-bit screen is about 150 kB, so at 40 MHz you get roughly 20 full frames per second - fine for a UI that updates fields, not for video or full-screen animation.

MCU parallel (8080 / 6800): the middle ground

Eight or sixteen data lines plus control, still with the frame buffer in the panel's driver IC. Several times the bandwidth of SPI for a dozen more pins. This is the classic choice for 2.4" to 4.3" colour panels driven by a mid-range MCU, and the same 6800/8080 signalling is what character and COG monochrome modules use.

RGB parallel: the host draws every pixel

The host outputs pixel data continuously with pixel clock, HSYNC, VSYNC and DE - typically 18 to 28 signals. There is no frame buffer in the panel, so the processor needs its own display controller and enough memory bandwidth to sustain the refresh. In exchange it is the cheapest way to drive a mid-size colour panel, which is why most of our 4.3" to 10.1" modules are RGB.

LVDS and MIPI: for higher resolution and longer cables

LVDS serialises the same RGB data onto differential pairs. Fewer wires, far better noise behaviour and it survives a longer cable, which matters when the panel sits in a door and the board sits in the cabinet. MIPI DSI is the modern equivalent on application processors: one or more high-speed lanes, low power, and the usual choice above about 1024x600 on an SoC that already has a DSI port.

UART smart modules: no graphics code at all

A smart serial module carries its own controller and screen layout. The host sends a command - set this field to this value - and the module renders it. It costs more per unit than a bare panel and removes the display firmware project entirely, which is usually the right trade below a few thousand units or when the host MCU is busy doing something more important. Our BMS protocol screens are this type.

What our catalogue actually offers per interface

This is the part you cannot get from a generic tutorial: the interface mix of the models we have published, so you can see where the choice is real and where it is theoretical.

Counted across the 103 models on this site that carry a full parameter set; generic “customisable” listings are excluded so they cannot inflate a count. A model that offers several interfaces is counted in each family.

Interface changes late in a project

Changing interface after the carrier board is laid out is the single most expensive display change there is - it is a board respin, not a panel swap. Decide it before the mechanical design freezes, and if you are unsure between two, tell us: several glass sizes exist in more than one interface version, and picking that model early keeps the option open at no cost.