The simplest and most frequently encountered home automation interface is the simple light switch. It is very intuitive, user friendly and unambiguous. Normally it only assumes one of two positions. The lights are either on or off, unless it is a dimmer switch, in which case it will assume any position between on and off. The problem is encountered when a multitude of switches are put together on a single panel and have to be labeled for the various light fixtures or control functions. The problem is further exacerbated when the switches not only control the lights but also fans, heating, air-conditioning, curtains, drapes, audio/video controls, etc. for home automation and entertainment.

Figure 1

The traditional user interfaces for entertainment and automation fall under three categories. The first is fixed command type keypads with push-button switches on a single or multiple gang boxes in the wall. They are typically pre-programmed to control specific automation functions such as the lights or Audio/Video sources. The functions are typically silk-screened or printed on the panels and cannot be programmed for devices other than the ones provided by the manufacturer. They usually have an IR detector that forwards IR commands from the rooms to the main control box for source control and automation. Figure 1 shows one such keypad for the control of background music only. As can be seen, it allows control of the volume, bass and treble, and source selection from one of six pre-printed labels on the panel. These types of keypads have a very limited functionality and are usually very much restricted to the operation of the system that accompanied them. They do not provide any control of the source components, lights or heating/cooling systems. Their pre- printed labels on the panels tend to be difficult to read, especially in poorly lit areas of the room and keypad layouts are confusing and aesthetically very bland. Despite the fact that these keypads have limited functionality, they are relatively expensive compared to simple learning universal remote controls.

The second is an IR learning type keypad that can be taught various commands for audio/video and home automation control. Typically these commands are learned from IR remote controls but sometimes they are retrieved from a library of IR or control codes. Figure 2 shows one such example of an IR learning keypad. These types of learning keypads tend to be expensive and are limited to single function per key. Again due to limited space on the panels the labels are hard to read or become fixed for specific tasks and are not flexible for other controls. There are too many buttons with fixed functionality. Aesthetically these IR learning keypad controllers are a little more attractive than the fixed control keypads shown earlier but they are still very expensive. Some IR learning keypads are even more expensive than an average PDA or a low end computer and have less computational power.

Figure 2

The third type of interface controllers are LCD touch screen devices that normally ranges from 4 inch to 10 inches in size and are available in monochrome or color. Figure 3 shows one such device. Usually these devices communicate to a central control system to execute the functions they are programmed for. It is possible to create macro buttons on the touch screens to execute multiple commands from a single button press. Normally the processing power resides in the system controller and the touch panels are simple input/output devices without any real “brains”. They simply accept the touch commands from the user and forward to the central control system, which then executes various functions related to lighting control, heating and cooling, audio/video controls, security, etc. Unfortunately these touch panels tend to be very expensive and without the main control system are useless on their own. Yet another drawback of the touch panel is the grease and dirt it accumulates on the touch surface. Also because of the nature of the touch panels, it usually obscures the very thing that the user is trying to press. This is specially a problem with elderly users who have difficulty operating these touch panels. Yet another shortcoming is the lack of tactile feedback. Most elderly users have a strong preference for positive tactile feedback when the keys are touched. It is impossible to provide a positive tactile feedback from an LCD touch screen. The full LCD screen does provide glamour and pizzazz to the user interface at a very high cost. Most of these touch panel controllers are more expensive and less powerful than standard laptop computers.

Figure 3

The new Pragmatic LCD keypad controller shown in Figure 4 addresses most of the functional, ergonomic and aesthetic problems associated with the earlier described products. At the core of this controller is a large TFT dot matrix blue LCD featuring high contrast and variable intensity backlighting to keep the display readable from a broad viewing angle in all lighting conditions. Below the sharp display, it has five fully programmable buttons with positive tactile feedback. The large powerful processor at the heart of this display makes its menu driven controller very intuitive and easy to use. It also sports a built-in temperature sensor, ambient light sensor, real time clock and calendar with alarm function, a serial data port (RS232 or RS485) for communications and an IR detector. The controller easily interfaces with X-10, CE-Bus and other networks as well. A wide variety of icons can be programmed on a computer and loaded into the controller via the serial port. Multi-level macros can be configured from a learned IR library and executed at the touch of a single button. Combination of macros with IR commands and RS485 commands can be mixed and executed on a single click of the button as well. The controller is well suited for entertainment as well as home automation including lighting control, HVAC control, security and surveillance. The keypad controller is designed primarily to interface with the CATS™ and DMS™ products from Pragmatic, but can easily interface with other systems as well.

Figure 4

Figure 5

Figure 5 shows a typical configuration screen to set the treble, bass and balance control for the audio system. Pressing the left most button on the keypad changes the screen to show up/down arrows for treble and bass controls. The right most button on the keypad is programmed as an “Enter” or “Escape” button. Pressing the second button will display the balance control for the speakers in the room. The third button is for adjusting the contrast on the LCD for better viewing in the room to individual preference. The fourth button displays another set of LCD menus the user can select from and execute via the four buttons on the bottom. Since all the graphic screens and icons can be programmed on a PC, it opens up limitless possibilities for the icons and its associated control functions.

Even though the keypad controller is primarily designed for Pragmatics’ CATS™ and DMS™ products, because of the interface and programming capabilities, it can easily control an X-10, CE-Bus or other systems.

Figure 6

Figure 6 shows a typical operational screen for controlling the volume, sources, lights and additional functions. The first two buttons control the volume in the room. The second button, if held down for an extra moment provides the instant mute function and a tap on either of the buttons releases from mute. The third button has a networking icon and is used for controlling the CATS™ router for source selection of audio/video programs. The fourth key is for lighting control. Pressing the fourth key changes the display and icons for various pre-programmed scenes and lighting conditions. The fifth button invokes more control icons on the screen. The simple and intuitive navigation of the menu using only five buttons keeps the display uncluttered.


The keypad controller from Pragmatic represents a major advancement in the ergonomics and aesthetics of a home automation controller that is attractive, intuitive and affordable. At a cost closer to the least expensive fixed keypad controller for audio distribution only but more features and functionality than the expensive touch-panel controllers, it represents a greater value to the user.

About the Company

Pragmatic Communications Systems, Inc., is a Silicon valley company established in 1994 to design, develop, and produce a variety of innovative products for wireless audio, video, and data communications. The majority of company’s products until 1997 were primarily designed for industrial and commercial applications. The success of these products has led to a strong and dynamic technology base, which has been applied to new generation of products such as CATSTM and others like the DMSTM, TrueMusicTM wireless hi-fi system and TrueViewTM wireless video system. The company’s philosophy is to use its technologies to solve problems that have gone unresolved for decades.

CATSTM, TrueViewTM, TrueMusicTM and DMSTM are trademarks of Pragmatic Communications Systems, Inc. Products and technologies described in this article have patents pending are also available for licensing to qualified manufacturers of consumer electronics products.

For more information:

Pragmatic Communications Systems, Inc.
544 E. Weddell Drive, Unit 8
Sunnyvale, CA 94089 USA
Tel. (408) 542 0330
Fax (408) 542 0339

Author’s biography

Prasanna M. Shah is the Chief Pragmatist and Thinker at Pragmatic Communications Systems, Inc. He earned his M.S. degree in Electrical Engineering from Stanford University and B.S. degree in Electrical Engineering from Santa Clara University, Santa Clara, CA. He is a member of Tau Beta Pi and Eta Kappa Nu Electrical Engineering Honor Societies. He has more than two decades of experience working on semiconductors for analog and digital audio, video, cellular telephones, wireless communications, fiber optic communications, data communications, data acquisition and industrial controls in the Silicon Valley. He holds one patent on power line communications and several patents pending on audio, video and wireless multimedia systems. An avid audiophile and music lover, in his free time, he likes to apply his pragmatic thinking to solve complex problems.