Micro2440/Mini2440 Beep c program in linux

Keywords: Micro2440, Mini2440, Beep, Beep

The buzzer support has been added to the default kernel of Micro2440/Mini2440 linux (see <micro2440 user manual -2010-6-9.pdf> P346). Therefore, you can directly operate the buzzer through the file ioctl.

(Ls/dev/pwm indicates that your Micro2440/Mini2440 has a buzzer function .)

The following code references <micro2440 user manual -2010-6-9.pdf>

# Include <stdio. h>
# Include <termios. h>
# Include <unistd. h>
# Include <stdlib. h>
 
# Define PWM_IOCTL_SET_FREQ 1
# Define PWM_IOCTL_STOP 0 // Note: <micro2440 user manual -2010-6-9.pdf>,
// PWM_IOCTL_STOP is defined as 2, which is incorrect;
// It should be consistent with the buzzer kernel code, which is 0
 
Static int fd =-1;/** <save the buzzer file handle */
 
/** Close the buzzer */
Static void close_buzzer (void)
{
If (fd> = 0)
{
Ioctl (fd, PWM_IOCTL_STOP );
Close (fd );
Fd =-1;
}
}
 
/** Open the buzzer */
Static void open_buzzer (void)
{
Fd = open ("/dev/pwm", 0 );
If (fd <0)
{
Perror ("open pwm_buzzer device ");
Exit (1 );
}
 
// Any function exit call will stop the buzzer
Atexit (close_buzzer );
}
 
/** Beep with freq */
Static void set_buzzer_freq (int freq)
{
// This IOCTL command is the key to set frequency
Int ret = ioctl (fd, PWM_IOCTL_SET_FREQ, freq );
If (ret <0)
{
Perror ("set the frequency of the buzzer ");
Exit (1 );
}
}
 
/** Stop beep */
Static void stop_buzzer (void)
{
Int ret = ioctl (fd, PWM_IOCTL_STOP );
If (ret <0)
{
Perror ("stop the buzzer error. \ n ");
Exit (-1 );
}
}
 
/**
* The beep function.
* \ Param freq beep frequency
* \ Param t1 the duration of each beep. Unit: milliseconds
* \ Param t2 beep times
* \ Remark: after testing,./testBeep 3000 2000 3 as a normal condition, the beep effect is better (3 times at a frequency of 3 K, 2 seconds at each time)
*./TestBeep 3000 500 20 as the Failure Alarm beep effect is better (3 K frequency beep 20 times, every 0.5 seconds)
*/
Static void Beep (int freq, int t1, int t2)
{
Printf ("freq = % d, each_ms = % d, ntimes = % d \ n", freq, t1, t2 );
Open_buzzer ();
Int I = 0;
For (I = 0; I <t2; ++ I)
{
Set_buzzer_freq (freq );
Usleep (t1 * 100); // * 100 is an experience value. Why ~
Stop_buzzer ();
Usleep (t1 * 100); // * 100 is an experience value. Why ~
}
Close_buzzer ();
}
 
/** Test Program main */
Int main (int argc, char ** argv)
{
Int freq;
If (argc> = 2)
{
Freq = atoi (argv [1]);
If (freq <1000 | freq> 20000)
{
Freq = 10000;
}
}
 
Int each_ms = 500;
If (argc> = 3)
{
Each_ms = atoi (argv [2]);
If (each_ms <100 | each_ms> 5000)
{
Each_milliseconds = 500;
}
}
 
Int times = 0;
If (argc> = 4)
{
Times = atoi (argv [3]);
If (times <1 | times> 30)
{
Times = 5;
}
}
 
Beep (freq, each_ms, times );
 
Return 0;
}
 
// EasyVCR @ csdn, 2012.01.04

Compilation: arm-linux-gcc testBeep. c-o testBeep

From EasyVCR's column