Embedded Linux®: Hardware, Software, and Interfacing

Summary

This chapter covers a tremendous amount of information. The Project Trailblazer engineers started off by establishing their input and output requirements for lift monitoring and snow-making control through discussions with the Operations Department. They investigated I/O boards and decided on PC parallel port use. They then designed an interface circuit to connect a PC parallel port to an input module board and an output module board. When they began writing control software, three approaches evolved: port I/O using inb and outb functions, parallel port control using the Linux ppdev device driver, and development of a custom device driver. The port I/O approach was simple. However, its use had drawbacks that make it too risky. The second ...