Electronic Design

EiED Online>> Building A Multimedia Kiosk

Lebro Industrial's all-in-on aluminum Lebro V8171 multimedia LCD (see Fig. 1) looked to be the ideal platform for building a multimedia kiosk. Its solid, all-metal design provides a rugged platform that includes stereo speakers. It can easily be used as a desktop PC or a standalone device. For the former, the unit comes with a CDRW/DVD drive that pops out on the left side, and a flash card reader with sockets for a variety of media on the right.

Pop the aluminum cover off the rear (see Fig. 2) and you see a large area for mounting a mini-ITX or micro-ATX motherboard, room for one or two PCI adapters, and room for one 3.5-in. hard disk. The small circuit board near the top is the audio amplifier. It can plug into an external jack or the cable can be replaced by one that connects directly to the interior of the motherboard.

System Design
The design criteria for this task was to create a multimedia kiosk with a minimal footprint and a touch-screen interface. While the Lebro V8171 has a touch-screen option, I decided to use a second, smaller screen from Amulet. This allows the user interface to be placed close to a user, and then the main screen could be mounted anywhere. The final system consists only of the Lebro and Amulet screens.

VIA's SP13000 (see Fig. 3) was chosen as the computing platform. Its hardware-based multimedia acceleration (MPEG-2/MPEG-4) can handle the streaming video expected on the system. In addition, it contains an extensive number of peripheral interfaces, including four sets of USB hubs. The Lebro V8171 uses two, and one is found on the back panel (see Fig. 4). It has Ethernet connectivity, and wireless support could be included using a PCI adapter.

The board is very quiet. It's possible to replace the CPU fan with a heat pipe or oversized heat sink, but this seemed a bit like overkill given the system power supply has a much larger fan. The power-supply fan is louder than the CPU fan, but still quiet compared to many desktop PCs.

The SP13000 can handle up to 1 Gbyte of DDR 400 memory. There is a VIA VT1623 TV encoder with composite video and S-video output. This feature would not be used in this particular application. The RCA jack can also be jumpered to deliver SPDIF audio output from the VIA VT1617A 6-channel AC'97 codec. The SP13000 also has an LVDS that can interface directly with an LCD display. In our case, the standard VGA interface is used instead.

The SP13000 supports IDE and SATA (Serial ATA) drives. Multimedia information takes up a good deal of space, so Seagate supplied a top-of-the-line, 7200-rpm, 400-Gbyte (now available in 500-Gbyte versions), SATA-interface Barracuda drive (see Fig. 5). The SATA drives provide higher throughput (3 Gbits/s) than do PATA drives, but they also use different cables. The data cables have only four connections, many fewer than the PATA data cable has. The power connections are smaller, but they provide the same voltages. The Barracuda also has up to a 16-Mbyte cache. It is also very quiet. The SP13000 supports RAID configurations as well, but we only needed a single drive.

Seagate also provided the mechanism for updating the multimedia content of the system. This is handled using a high-speed, USB 2.0 interface and Seagate's 400-Gbyte external hard drive (see Fig. 6). The drive could also have been connected to the IEEE 1394 connection on the SP13000, but this is an internal connection. It also would have been possible to use one of the two PCI slots for a cable/connector combination.

SuSE Linux and Embedded Windows XP are ideal choices for driving the platform. I had both handy so a dual boot setup was used to test the system.

Building The System
Construction of the main system is very easy because the speakers, CDRW/DVD drive, and USB flash-memory-reader devices are already mounted inside the case. The USB flash memory reader supports Compact Flash, Memory Stick, Smart Media, and Secure Digital. The rear cover is held on by a dozen screws around its perimeter. Once removed, we have complete access to all the mounting points and cables.

The documentation recommends placing the unit face down while working on it, so a soft area or pad is in order. The hard disk drive has plenty of air space for cooling and the mounting holes are easily accessible. We had to use a SATA power drive adapter as the Lebro power supply comes with the standard 4-pin power connectors.

Next, the motherboard back plate was installed and then the motherboard. Standoffs and mounting screws are included with the Lebro LCD unit. The only two things added to the motherboard, other than cable connections, were memory and the PCI adapter. The latter comes with the LCD unit and allows a PCI adapter to be mounted parallel to the motherboard instead of perpendicular to it.

Cable connections include the power cable, the audio amplifier cable, the CDRW/DVD audio cable, the CDRW/DVD IDE cable, and the hard-disk SATA cable. There are also two USB cables that plug into headers on the motherboard along with a set of small power/reset switch and LED status cables.

The whole process takes less than half an hour including remounting of the case cover. The cover is added after the motherboard and drives are tested.

User Interface
The 5.7-in. Amulet-on-a-Board (see Fig. 7) is connected to the SP13000's serial port. This is easily done using the RS-232 adapter board, but a production system would more likely use a ribbon cable that plugs into the back of the unit (see Fig. 8) instead of the adapter board. Because the connector includes the power connections, it would be possible to bring a cable into the back of the Lebro and provide a serial connection and power over the same cable.

The Amulet board does not have its own case. This would be part of a production design. The only requirements on the system design would be space for the LCD screen and the appropriate mounting holes. The unit is already backlit.

I have not mentioned it yet, but the Amulet-on-a-Board contains Amulet's Graphical OS chip. This takes a compiled HTML package to generate an interactive user interface. It interacts with a user via a built-in touch panel and with a host via the serial port. Graphical presentation and layout is done using conventional HTML and Flash support, although an Amulet compiler creates a block of data that is processed by the Graphical OS chip. Flash memory on the board maintains the application.

The Amulet development kit comes with a range of examples, but you need to provide your own HTML editor and Flash editor. Compilation and download is a trivial task. A monitor and simulator provide a fast way to evaluate and debug an interface. I did not get into dynamically downloading images as only static images are required when the button interface does not change.

The Amulet interface over the serial port can operate in master or slave mode. In master mode, actions from the user working with the touchpad initiate data transfers to the host. In slave mode, the host issues serial commands to the board that responds with the requested data.

It turned out that a simple configuration was very easy using Linux. There are a number of scripting languages including the bash shell that can access the serial port directly. Creating an application such as one that would present a list of videos to play is very straightforward.

Windows also has a nice way of doing the same job-Visual Basic. This is an especially nice approach if the presentation is done on the Lebro screen and the Amulet is used as a soft keyboard. Visual Basic easily handles the serial interface so the tradeoff between Windows and Linux tends to be the platform you are more familiar with. Of course, it may also be dictated by the kinds of multimedia codecs required by the application.

The Lebro V8171 provides a smart looking, multimedia platform and the Amulet-on-a-Board provides a fast and simple way to deliver a flexible user interface.

Related Links
Amulet Technologies

Lebro Industrial Inc.



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