motherboard buzzer

Whether it is a buzzer or LED digital tube display, in fact, the two for code writing is not much different, are gpio a typical application. Red Bull Development Board has a buzzer, and EM-STM3210E has a four-bit led digital tube, the code is relatively simple, not worth the two write a separate blog, so the two in one article to explain, but two sample code is independent. First, the

driver module is useless by any other Linux The drive module is used, but the display has been referenced once. The key to this situation is that the value of the reference counter is inconsistent with the reference. In fact, the reference does not exist, so you only need to clear the current Linux Driver module reference counter 0. The following two functions can be used to modify a reference counter.static inline int try_module_get (struct module *module)//enable module to point to the Linux

The Samsung Development Board comes with a buzzer, so we can control the buzzer by writing a specific value to the register. When developing a driver, an error may occur in functions such as Init, exit, and so on, which is the possibility that the driver will fail to install, and, worse, the inability to use the Rmmod driver, which can cause an inability to install again. There are many ways to reuse Linux-

The sound of the active buzzer is fixed, the operating voltage is constant, changing the time of the power off to obtain a different length of sound, such as continuous, fast short, slow long sound (similar to Morse Telegraph) to distinguish different alarm information.Simply put, the active buzzer can only emit one sound because its frequency is fixed. can only be differentiated according to the different

normally.The key to this situation is that the value of the reference counter is inconsistent with the reference.Adds 1 to the reference counter of the Linux driver that the module points to, returns 1 successfully, and 0 failsstatic inline int try_module_get (struct module *module)Subtract 1 from the reference counter of the Linux driver that the module points toExternvoid module_put (struct module *module)(2) The Unload function is blocked: When uninstalling the Linux driver using the Rmmod c

Code reuse is divided into static and dynamic. Static reuse is when you use certain features, include the corresponding header file. Dynamic reuse is a Linux driver that can use resources from another Linux driver. When compiling multiple source code files in the C or C + + language, if A.C uses the functions in the B.C file, you need to use extern to pre-define the B.C in the a.c file, and extern is to tell the compiler the function name, the number of arguments, the parameter type, and the ret

We have explained in detail the Raspberry Pi control ultrasonic module ranging (http://www.cnblogs.com/yuemo/p/8888342.html) and ultrasonic control buzzer module audible (http://www.cnblogs.com/ yuemo/p/8906111.html).Today we'll see how to apply all two modules and make an anti-theft device.First look at the connection of each pin (requires seven mother-to-female DuPont line):Ultrasonic module:1.VCC: Connect 5V power supply (pin 1th)2.Trig: Output por

Microcontroller Remote Control stepper motor, LED lights and buzzer The stepping motor module, LED lamp and buzzer module of the single-chip microcomputer are controlled by the C # language to enable the stepping motor to perform forward, reverse, and stop and control the speed; the LED lamp module performs selective breathing expression; the start and end of the buzzer