Chapter 8. USB Interfacing
| IN THIS CHAPTER
Silverjack guests enjoy music and photographs. Whether it's Mozart in the village or Nine Inch Nails in the half pipe, people enjoy outdoor music and continually make positive comments. Project Trailblazer will enhance the mountain's audio capabilities. Pictures also play an important role at Silverjack. Images are used around the mountain to provide current status information. "How long is the Lift 4 line?" and "Is it snowing at the top of Lift 9?" are common questions that could be immediately answered with pictures. With current mountain images, guests can make decisions about where to go on the mountain in order to avoid long lift lines. Images also enhance safety by allowing guests to view the mountaintop conditions. If it's snowing up high, some people might decide to stay low. Project Trailblazer image collection will enhance both guest enjoyment of Silverjack and their safety. This chapter follows the Project Trailblazer engineers as they use embedded Linux to play music and collect images. Linux audio is easy: You install a sound card, recompile the kernel, and reboot. Similarly, for video, you install a video capture card, recompile, and reboot. But these simple processes are possible only if the kernel supports the sound card and video capture card. Many devices don't have Linux support, or the support is via reverse-engineering that provides an unofficial solution. Cost is a big consideration for Project Trailblazer. Sound cards, which are a commodity item, are inexpensive. Video capture and the associated cameras, on the other hand, are relatively expensive. Project Trailblazer requires image capture at the bottom and top of each lift, as well as in other Silverjack locations. Equipment costs will therefore add up quickly. The engineers need a low-cost solution for audio playback and image capture. Unfortunately, the Project Trailblazer target platforms don't have peripheral component interconnect (PCI) card bus connectors. Therefore, the engineers opted to use universal serial bus (USB) speakers and cameras. The consumer market has driven the price of speakers and cameras very low in the $30 range. The engineers knew that the majority of USB devices available today ship with Microsoft Windows drivers. They didn't know whether devices and their drivers support Linux. The engineers figured that if the drivers did not exist, they might have to write their own. |
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