Design custom LCD display controller
INDUSTRIAL LCD DISPLAYS / IGBT MODULES DISTRIBUTOR

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

Design custom LCD display controller

Posted Date: 2024-02-01

One of the initial decisions to make is to define what the controller is expected to accomplish and under what conditions it must perform—other constraints such as PCB footprint and cost will arise later in the project. Some of the main decisions that need to be made include what resolution to display and what input interface is required. Supported input resolutions are not necessarily limited to the display resolution of the LCD, as current display controllers often support upscaling of lower resolution data to match the LCD, and some can even support downscaling, where complex algorithms are used to reduce the resolution of the data. to adapt to the available display formats of the LCD.Supported interfaces may cover a wide selection, including support for industry-standard ARGB interfaces for PC input

With some idea of ​​the basic standards in mind, the next factor to consider is choosing the right "engine" to provide the intelligence to accomplish all of these tasks. A controller engine is typically a high-density, single-chip, single-purpose device built by one of a handful of developers. Major companies in this industry include companies such as Genesis, Pixelworks, and ST Micro. Each of these companies sells one or more specialized controller chips that are designed to emulate controller designs. Controller components vary widely in functionality, flexibility, complexity, and cost. Considerations when selecting include reviewing not only the performance and functionality of the chip, but also the development environment and available support. Many vendors offer reference designs to accelerate hardware development and basic software development kits. Development kits usually provide basic startup code and a utility package suitable for getting a basic display on the screen, but require extensive development to mature into a complete product with appropriate functionality and stability. One consideration here is development support. These components are developed by manufacturers who intend to sell to set-top box manufacturers, high-volume desktop monitor manufacturers, etc. "So they may be less willing to support someone who makes hundreds of products per year. In some cases, The manufacturer will make a purchase requirement before any support is provided. Development kits usually provide basic startup code and a utility package suitable for getting a basic display on the screen, but require extensive development to mature it into one with appropriate functionality and stability complete product. One consideration here is development support. These components are developed by manufacturers who intend to sell to set-top box manufacturers, high-volume desktop monitor manufacturers, etc., "so they may be less willing to produce hundreds of products per year." people provide support. In some cases, manufacturers will require purchase before providing any support. Development kits usually provide basic startup code and a utility package suitable for getting a basic display on the screen, but require extensive development to mature into a complete product with appropriate functionality and stability. One consideration here is development support. These components are developed by manufacturers who intend to sell to set-top box manufacturers, high-volume desktop monitor manufacturers, etc. "So they may be less willing to support someone who makes hundreds of products per year. In some cases, Manufacturers will make purchase requirements before providing any support. One consideration here is development support. These components are developed by manufacturers who intend to sell to set-top box manufacturers, high-volume desktop monitor manufacturers, etc., "so they may not be very Would love to support someone who makes hundreds of products every year. In some cases, manufacturers will require purchase before providing any support. One consideration here is development support. These components are developed by manufacturers who intend to sell to set-top box manufacturers, high-volume desktop monitor manufacturers, etc. "So they may be less willing to support someone who makes hundreds of products per year. In some cases, The manufacturer will request a purchase before providing any support.

There's a lot more work to be done depending on the chipset chosen, the definition of the input ports, and the desired display resolution. Depending on the supported inputs, the design will require an appropriate analog-to-digital converter with performance suitable for the application to manage inbound ARGB signals, DVI receivers, and other decoders. Decoders and receivers represent the input ports of the controller, and with that comes the responsibility for ESD and EMI, as well as the need to provide protection against incorrect connection of the ports (overvoltage, reverse polarity protection, etc.).

place it on the panel

After providing a port for inputting data into the controller, the next step is to output the data from the controller to the LCD panel. Due to the volatility in the LCD panel industry, major decisions must now be made regarding the products planned to be used "now and in the future." LCD panels have a short lifespan. Due to rapid advances in manufacturing technology, LCD companies continue to improve resolution, viewing features, and interfaces. So there's really no point in developing an LCD controller without planning to support multiple panels to prevent the primary choice from becoming obsolete.

Multi-panel support

Support for multiple panels now forces designs to adapt to provide switches or other mechanisms to provide a selection mechanism for the alternating timing required by different panels. Any kind of selection mechanism now adds some new requirements for extra intelligence. It was necessary to add a microcontroller and some code to run it to make these selections possible, and of course add some displayed menus to allow the user to configure the system.

The panel interface is the next issue to be dealt with. Whether the panel has a TTL or LVDS interface, 6-bit or 8-bit color, dual pixel or single pixel, and what type of connector is required. There are many options to analyze and resolve.

Solve multi-panel challenges

Once these problems are defined, one of the really hard jobs can begin, which is solving the "multi-panel" and "multi-input" puzzles. Each LCD panel model, even with similar electrical interfaces, may have different timing requirements to create a stable image. To further complicate matters, data received on different ports (i.e. DVI vs video) may require timing adjustments in each mode for successful display. Supporting multiple panels makes this very complicated, and it becomes extremely difficult to build a universal controller that can support a variety of panel resolutions and input ports.

Although all the major components are in place, there are still a number of issues that need to be addressed to ensure that the product is reliable and effective. Reliability is a critical feature that must be designed into the product and cannot be added later. Following good design practices and performing detailed load analysis at every stage of hardware design, followed by final detailed design proof, ensures operation with adequate and predictable margins. With a stable hardware design, MTBF (Mean Time Between Failures) analysis can be completed using software tools to provide an indication of predicted product reliability.

For a truly flexible LCD controller design, we can foresee the need for an extremely flexible, robust and power supply. LCDs require a stable power supply because any noise or ripple is immediately communicated through the display with catastrophic effects. A proper design will accommodate a wide range of input voltages and significant noise immunity, as there may be some noisy devices such as an inverter with variable duty cycle operating on the same rail.

View Figure 2 Full Size

Figure 2 shows the additional steps that must be taken to address the remaining 20% ​​of the design, which may impact the performance of the controller. This addresses issues such as ESD and EMI, power supply regulation, and termination circuitry between the LVDS transmitter and receiver.

There are many more factors that need to be considered in the design of an LCD controller before it can become a viable product. These include difficult areas such as EMI, RFI performance, ESD protection, operating temperature, and of course ensuring product compliance with new regulations such as RoHS.

Is there a more practical option?

Therefore, a more practical alternative to designing your own controller board might be to purchase a controller such as the Digital View SVH-1920 (see photo), which is standardized on a single platform and supports multiple panels. Often, individual project volumes do not justify a unique design and production run; leverage existing products that fit your application. And consider development support: If production volumes are low or your company doesn't have good relationships with component manufacturers, it can be difficult to get support.

And consider time to market. Buy from a company that specializes in flat panel controller boards, with a fault-tolerant architecture and a highly flexible universal design that supports multiple panels, meaning your solution is ready to go. The delivery time can meet your needs.

Of course, there’s also price to consider. For specialized, low-volume niche applications, you won't realize any economies of scale from designing your own controller anyway.

Furthermore, a suitable controller would provide extensive industry knowledge based on years of experience in designing these boards, as well as advanced technical knowledge, resulting in products such as EEPROM ICs that provide timing for different panels (multiple timing libraries embedded in the chip make it multi- a panel) or an LVDS transmitter (enabling LVDS receivers to be implemented in a variety of ways on the panel).


#Design #custom #LCD #display #controller