Driving Large LCD Screens with Microcontrollers: A Cost-Effective Alternative to Linux Platforms

Engineering excellence is hardcoded into all we do here at Genesys and we’re constantly looking to drive innovation and push the boundaries of what is possible. We are launching our Engineering Innovation Series to share the technical breakthroughs we are making on different projects. We hope sharing our approaches and insights helps spark conversations and inspire collaboration and further innovation within our Australian Engineering Community.

12-inch high resolution LCD screen

Embedded systems often require local displays for user interaction, whether it’s for monitoring measurements, adjusting settings, or providing real-time feedback. While small screens (typically under 5 inches) are commonly driven by microcontrollers, larger screens (8 inches and above) have traditionally required more powerful processors, often running Linux.

Linux platforms, such as those built around i.MX processors, are designed to handle the intensive processing and memory demands of high-resolution displays. However, they come with significant drawbacks:

• Higher cost: Linux platforms can be expensive, while high-performance MCUs offer a more budget-friendly alternative without sacrificing functionality.

• Increased complexity: Linux platforms require more memory, longer boot times, and additional development effort.

• Performance concerns: For real-time applications, the overhead of a full operating system can introduce latency and reduce responsiveness.

• Regulatory compliance. For function-critical applications such as medical devices, achieving regulatory compliance for Linux platforms can be problematic.

But what if you could drive a large LCD without the cost and complexity of Linux?

At Genesys Electronics Design, we’ve developed an innovative approach that avoids these limitations by designing a solution for driving 12-inch high resolution LCD screen using advanced MCUs running RTOS. Our goal was to implement a large screen (greater than 10 inches) without resorting to an embedded Linux platform. By choosing the ST Microelectronics STM32H7, we achieved a robust solution that maintained performance while leveraging an RTOS-based microcontroller.

Why Choose a Microcontroller?

Microcontrollers are the backbone of embedded systems. They are cost-effective, energy-efficient, and ideal for real-time applications. Historically, they have been limited to driving smaller low-resolution screens, typically under 5 inches. Larger, high-resolution screens require more processing power and memory, along with multi-lane high speed digital interface, which is why many developers turn to more powerful platforms.

But modern MCUs have evolved. With advancements in processing power, integrated GPUs, and RTOS compatibility, MCUs like the STM32H7 from ST Microelectronics are now capable of handling larger displays without compromising performance or interface options. Here’s why this approach is worth considering:

• Cost Efficiency

The STM32H7 microcontroller starts at a fraction of the cost of higher-end platforms, making it an attractive option for budget-conscious projects.

• Faster Boot Times

Microcontrollers boot up almost instantly, thanks to the minimal overhead of a Real-Time Operating System (RTOS). In contrast, more complex platforms can take several seconds to initialise, which can be a deal-breaker for real-time applications.

• Real-Time Responsiveness

RTOS allows for task prioritisation, ensuring that screen-related tasks are handled efficiently. This results in a highly responsive and fluid user experience.

• Energy Efficiency

Microcontrollers are inherently more energy-efficient, making them ideal for battery-powered or energy-sensitive applications.

• Regulatory Compliance

Versions of RTOS are available which are compliant with standards such as IEC 62304 for Class B and C medical devices.

The STM32H7: Powering a 12-Inch LCD Screen

At the heart of our solution is the STM32H7 microcontroller from ST Microelectronics. This MCU is a powerhouse, designed specifically for screen-intensive applications. Here’s what makes it stand out:

Key Features of the STM32H7

• 600 MHz Processor: Delivers the processing power needed for high-resolution displays.

• Integrated GPU: Handles graphics blending and rendering, ensuring smooth visuals.

• RTOS Compatibility: Enables real-time task prioritisation for a responsive user interface.

• Cost-Effectiveness: Offers high performance at a fraction of the cost of more complex platforms, making it an ideal choice for budget-conscious projects.

The Technical Hurdles of Driving Large LCD Screens with Microcontrollers

Driving large LCD screens with a microcontroller might seem like a straightforward task, but it comes with its fair share of challenges. These hurdles, while significant, are not insurmountable, especially with the right tools and expertise. Let’s take a closer look at what these challenges are and how they can be addressed.

1. Interface Compatibility: Bridging the Gap

One of the first hurdles is the difference in display interfaces. Many microcontrollers, like the STM32H7, support RGB output, but high-resolution screens often use multi-lane LVDS, which is more common for larger displays. To solve this, we designed the hardware to support RGB to LVDS conversion. This ensures seamless communication between the microcontroller and the display while maintaining a smooth 60 fps refresh rate for crisp, responsive visuals.

2. UI Development: Keeping It Simple and Effective

Designing a user interface for a large screen can be complex, especially when working with limited resources. Tools like ST Microelectronics’ TouchGFX platform can simplify this process. While it requires some manual effort for intricate designs, TouchGFX offers a library of pre-built elements and templates, making it easier to create polished, responsive interfaces without starting from scratch.

3. Memory Management: Optimising Performance

Another challenge is managing memory efficiently. Microcontrollers like the STM32H7 rely on external memory to store application data and screen assets, such as images and icons. Implementing smart memory management techniques ensures the system runs smoothly without hitting storage limits. This not only boosts performance but also helps keep costs under control.

4. Real-Time Performance: Enhancing User Experience

Driving a large screen requires real-time performance to ensure smooth transitions and quick responses to user inputs. Using an RTOS (Real-Time Operating System) allows for task prioritisation, ensuring that screen-related tasks are handled efficiently. This results in a highly responsive and fluid user experience, even on resource-constrained hardware.

The Benefits and Applications of Our MCU-Driven Solution

Our MCU-based approach to driving large LCD screens offers a range of advantages, including optimised performance with smooth graphics and fast response times, simplified development using tools like TouchGFX, and a scalable design that adapts to various screen sizes and configurations. The reliable operation of an RTOS ensures consistent performance, even in real-time applications, while the STM32H7’s advanced features future-proof the solution as display technologies evolve. Additionally, the use of an IEC 62304-compliant RTOS alleviates regulatory concerns, making it an ideal choice for medical device applications. This cost-effective technology is incredibly versatile, making it ideal for industrial control panels, medical devices requiring high-resolution displays, and consumer electronics like interactive kiosks and smart home devices.

Why This Approach is a Game-Changer

Driving a 12-inch LCD screen with a microcontroller is a challenging but rewarding endeavour. By addressing interface compatibility, streamlining UI development, optimising memory, and ensuring real-time performance, we’ve shown that it’s possible to create high-performance, cost-effective solutions without relying on more complex platforms.

At Genesys Electronics Design, we’re all about pushing the boundaries of what’s possible in embedded systems. Whether you’re designing an industrial control panel, a medical device, or a consumer product, we’re here to help you innovate and succeed.

Got a project in mind? Let’s chat!

Contact us today to learn more about how we can help you drive your next big idea.