Reading notes (eight)

Make the Development Board sound: Buzzer driver

The buzzer is a hardware device on the s3c6410 Development Board. You can control the buzzer by writing a specific value to the register. The introduction of the buzzer to realize the original plow, and the realization of a complete buzzer drive, can open and close the buzzer when the drive is implemented differently than the LED PWM drive will be composed of multiple files. This is also the standard implementation of most Linux drivers, which means that a complex driver is unlikely to put all the code in a file. It is a good idea to put the closed code in the appropriate file. These files are co-compiled when the Linux driver is compiled. This section describes how to divide a Linux drive into multiple files. The data structure, function code in these files can also be used by several different drivers, which is also an important method of code reuse.

LED Driver code reuse, compilation is composed of multiple files Linux driver, Linux driver module dependency (export symbols).

Forcibly uninstalling the Linux driver, if you write the Ljnux driver is logically correct, then can load and unload normally, but in some cases, some programs can be abnormal situation. This Linux driver may not uninstall properly. initialization function crashes; unload function is blocked

Buzzer PWM driver, buzzer is also called PWM pulse width modulation, the basic principle is to control the buzzer by pulse to open and stop. For convenience, the book will be a bee, collectively referred to as PWM.

The PWM driver is similar to the implementation process of the ED driver and may be simpler. In this chapter, we just described how to separate the Linux driver implementation files, using a simpler PWM driver. Through the study of this chapter, we can master the common code reuse mode of Linux driver.

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Reading notes (eight)