2.4-inch LCD Screen Application with 6-bit Serial RGB Interface in Electronic Products

     2.4-inch LCD screens with 240*320 resolution are very common in the market, and their interfaces are usually standard.  Today, engineers at Shenzhen Hongjia Technology will share a less common interface: the 2.4-inch TFT screen with a 6-bit serial RGB interface. This combination offers an excellent balance between cost, performance, and design complexity, and is widely used in low-to-medium-end devices that require a certain level of display quality.

1. What is a 6-bit serial RGB interface?

A. RGB: Refers to driving each pixel of the screen using red, green, and blue primary color data lines.

B. 6-bit: Indicates that the depth of each color component (R, G, B) is 6 bits, i.e., 64 levels of grayscale. The combined color depth of a single pixel is 262K colors (64 * 64 * 64 = 262,144). This is slightly lower in color fidelity than the common 16-bit (65K colors) or 24-bit (16.7M colors) RGB, but it is generally sufficient for many non-professional image applications for the human eye.

C. Serial: This is the key. Unlike traditional parallel RGB interfaces (which require a large number of data and control lines such as VSYNC, HSYNC, DE, D0-D15/23, usually >20 lines), serial RGB transmits the RGB data of each pixel through a pair of differential clock lines (CLK+/CLK-) and 3 pairs of differential data lines (R+,R-; G+,G-; B+,B-) at high speed.

D. Number of physical lines: 6 pairs of differential lines + possible ground and power lines, significantly reducing the number of lines (usually only 8-12 physical cables).

E. Protocol: Usually follows a simplified form of the MIPI D-PHY's DSI (Display Serial Interface) protocol, or a higher-level variant of the SPI interface. In consumer-grade 2.4-inch screens, it is often simply referred to as "serial RGB" or "SPI RGB interface," essentially using a serializer to convert parallel RGB signals into a serial data stream.

 2. Combined Advantages (Why this design?)

This combination of "small screen size + medium-to-low color depth + serial interface" demonstrates the following core advantages in applications:

A. Significantly reduced wiring: This is the most prominent advantage. Reducing the number of wires from 20+ in a parallel interface to around 10 results in:

Less space required for routing between the main controller and the screen, potentially reducing the number of PCB layers and simplifying the layout.

The use of smaller, cheaper FPC connectors, saving space and BOM costs.

Fewer wires lead to a lower failure rate at connection points and easier anti-interference design.

B. Reduced cost:

PCB costs, connector costs, and assembly costs are all reduced due to fewer wires.

The number of GPIOs required by the main control chip is reduced, allowing for the selection of a more economical MCU or MPU with fewer pins.

C. Reduced power consumption:

Serial differential signals have a lower voltage swing and less electromagnetic interference, resulting in lower power consumption compared to parallel TTL level signals.

Fewer wires mean less parasitic capacitance, and the power required for driving is correspondingly reduced.

D. Meeting performance requirements:

For a 2.4-inch QVGA screen, the total number of pixels is 76,800. At a 60Hz refresh rate, the required data bandwidth is approximately: 76800 * 18 bits/pixel * 60Hz ≈ 83 Mbps. Even with 6-bit color (18 bits/pixel), the typical speed of a serial interface (hundreds of Mbps to over 1 Gbps) is more than sufficient, leaving ample headroom.

     Shenzhen Hongjia Technology is mass-producing 2.4-inch LCD displays with a 6-bit serial RGB interface, model HJ2408-18-A1.  We welcome inquiries from customers via email. The 2.4-inch LCD screen with a 6-bit serial RGB interface is a highly optimized embedded display solution. Through the key technology of interface serialization, it achieves simplified design, improved reliability, and reduced overall cost without significantly sacrificing visual experience (for small-sized, non-professional image applications), making it one of the classic choices for displays in modern compact smart devices.