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The Anatomy of a Display Module: Hardware

Welcome to the inaugural Serious Integrated blog! Our hope is that these blogs will help reframe the way you think about developing embedded systems and lead you to develop more polished, efficient and modern embedded systems from user friendly human machine interfaces (HMI) through communication and control. Let’s kick-off this first blog with a look at the hardware that makes up the anatomy of a display module.

A display module is not just a Liquid Crystal Display (LCD) that will present a picture to a user and a touch screen for human interaction. A display module is a highly integrated real-time embedded system that is tuned to efficiently interact and communicate with its environment. The LCD and touch screen are certainly important, outward facing factors but behind the scenes, there is much more to a display module than meets the eye. Let’s examine the major hardware components that are included in a display module using the Serious Integrated Module 543 (SIM543) as an example.

Summary of Major Components

The display module is made up of several components which include:

  • The LCD
  • A touch screen
  • Touch controller
  • Backlight
  • Video controller
  • Hardware accelerators
  • Memory controllers
  • ADC/DAC’s
  • Embedded peripherals (SPI, I2C, UART, I2S, GPIO, etc.)
  • USB
  • An ambient light sensor
  • Security and encryption engines

It turns out that this isn’t even an exhaustive list but just a quick summary of the major components. The complete list can be gleaned from the SIM543 block diagram shown below:

SIM543 Block Diagram
blog_SIM543_serious-module

A Deeper Dive

As you have probably already surmised, a display module is a complicated embedded system and not something that a development team should lightly decide to develop on their own. Let’s take a few moments to discuss a few of these major components.

First, let’s look at the SIM543’s heart, the Renesas Synergy™ S7G2 microcontroller. This real-time microcontroller provides the SIM543 module with an efficient, 32-bit microcontroller that provides all the peripherals and capabilities that one would expect from a modern real-time processor. These capabilities are made accessible to the HMI developer to communicate and interact with external devices through various peripheral interfaces. This makes it possible for the display module to interact in complex ways with its environment and even the cloud if the designer so desires. These capabilities are available through the 60-pin expansion connector or through other connectors available on the SIM.

As would be expected, the S7G2 has a very powerful graphics subsystem that can generate beautiful graphics and interface to a wide variety of LCD’s. To ensure that the graphics and application run smoothly, the SIM543 has several different memory sources that are available for application and storage purposes. These include an internal 3-megabyte flash storage for application code and graphics, an external 2 gigabyte e.MMC flash memory chip which expands this capability and then 640 kilobytes of internal RAM with an additional 32 megabytes of external SDRAM.

Each SIM will also vary slightly in the additional capabilities that are built into the display module. For example, the SIM543 also includes a piezo electric buzzer, an RGB LED and an ambient light sensor. These can be used in an HMI to notify a user audibly or visually that their device requires their attention or even to adjust the backlight duty cycle based on lighting conditions.

Simple & Elegant Interaction: 5 Connections

While the capabilities that are available in a SIM may at first seem a bit overwhelming, the SIM provides a simple and elegant manner for interacting with it. For example, examine the diagram below. You’ll quickly notice that there are just five connections that a developer needs to be familiar with. First, there is a device USB port that can be used to load a GUI, update the module’s firmware, and communicate with the module during development, production programming, and even in the final system. The SHIP programming port (SPP) also exposes the same USB device port but with a fast attach/detach magnetic connector generally used in the production line equipping of the module as it is installed in the final system. Next, depending on the application, a developer can use the JST 16-pin expansion connector and/or the FCI-60 pin expansion connector to interface to external devices such as control boards, communication devices and so on. The expansion capabilities are left only to the imagination and the requirements of the end application. Finally, there is also a USB host connector available on some models where an application may require an external USB thumb drive for in-system GUI and firmware updates.

As we’ve started to explore, there is far more to a display module than simply an LCD and touch screen. Properly utilizing these capabilities in an application successfully and quickly will dramatically depend upon the software that is used to develop the HMI and that runs the display module. In our next post, we’ll start exploring the software that is required to drive the SIM543 module along with the SHIP Tide software that allows a developer to quickly create an HMI.

A Serious Tip for the Thoughtful Engineer

As we have seen in today’s post, a display module is not a simple device. Developing one from scratch will take considerable time and be filled with unknown issues; For example, the ability to easily scale the solution and / or support multiple LCD’s. The quickest way to market is to leverage existing technologies and not try to create the entire solution yourself. Ask yourself where your value add is in the design and for everything else, leverage what already exists.

Jacob Beningo, Editor in Chief

Written by Jacob Beningo, Editor in Chief on 3/28/18 8:00 AM

Jacob Beningo is an embedded software consultant with over 15 years of experience in microcontroller based real-time embedded systems. Jacob is an avid writer, trainer, consultant and entrepreneur who transforms the complex into simple and understandable concepts that accelerate technological innovation. He has published more than 200 articles on embedded software development techniques, is a sought-after speaker and technical trainer who holds three degrees which include a Masters of Engineering from the University of Michigan.

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