The 8th chapter makes the Development Board sound, buzzer driver

Section 8 Chapters make the Development Board sound, buzzer drive

Experience

Create a makefile file under the directory

Run the make clean command to make sure that you compile some of the generated project files, execute the Make command, and recompile the driver. Copy the compiled generated Buzzer.ko kernel image file, adb push buzzer.ko/fpga/moudles

Then insert the kernel image file into the system, Insmod Buzzer.ko, and load the device driver, Mknod/dev/buzzer C 248 0

Now it is possible to write C + + files directly in the library layer to invoke this driver, this can install the NDK compilation environment in Ubuntu, create a new buzzer file, compile and build a library file, so you can directly at the application layer to use the library provided by the JNI method, the invocation will be more simple, Of course this call way Google does not advocate, I just want to show this kind of calling method here

Construct a JNI project and create a new BUZZER.C source file

The NDK compiles, generates libbuzzer.so, and the library can be called directly at the application layer

2. #include <reg52.h>
4. Sbit BUZZ = P1^6; //Buzzer control pin
6. unsigned char t0rh = 0; //t0 High-byte of overloaded values
8. unsigned char t0rl = 0; //t0 Low byte of overloaded value
10. void Openbuzz(unsigned int frequ);
12. void Stopbuzz();
16. void main(){
18. unsigned int i;
20. Tmod = 0x01; //config T0 works in mode 1, but does not start first
22. EA = 1;
24. While (1){ //enable global interrupt
26. Openbuzz(4000); //Start buzzer at a frequency of 4KHz
28. For (i=0; I<40000; I+ +);
30. Stopbuzz(); //Stop buzzer
32. For (i=0; I<40000; I+ +);
34. Openbuzz(+); //Start buzzer at a frequency of 1KHz
36. For (i=0; I<40000; I+ +);
38. Stopbuzz(); //Stop buzzer
40. For (i=0; I<40000; I+ +);
42. }
44. }
46. /* Buzzer start function, frequ-operating frequency */
48. void Openbuzz(unsigned int frequ){
50. unsigned int reload; Calculate the required timer reload value
52. Reload = 65536 - (11059200/N)/(frequ*2); //Calculate timer reload value by given frequency
54. T0RH = (unsigned char) (Reload >> 8); //16-bit overloaded value decomposed to two bytes high and low
56. T0RL = (unsigned char) reload;
58. TH0 = 0xFF; //Set an initial value close to the overflow so that the timer is put into operation immediately
60. TL0 = 0xFE;
62. ET0 = 1; //Enable T0 interrupt
64. TR0 = 1; //Start T0
66. }
68. /* Buzzer Stop function */
70. void Stopbuzz(){
72. ET0 = 0; //Disable T0 interrupts
74. TR0 = 0; //Stop T0
76. }
78. /* T0 Interrupt Service function for controlling buzzer sound */
80. void InterruptTimer0() interrupt 1{
82. TH0 = T0rh; //Reload load value
84. TL0 = T0rl;
86. BUZZ = ~buzz; //Invert buzzer control level
88. }

The 8th chapter makes the Development Board sound, buzzer driver