linux 驅動之PWM蜂鳴器驅動

table of contents

1、常用pwm函式

2、驅動程式設計例項

3、應用程式設計

4、pwm裝置樹節點配置

5、核心配置

6、測試

//申請乙個pwm裝置

pwm_device *pwm_get(struct device *dev, const char *con_id);
//配置pwm週期和占空比
int pwm_config(struct pwm_device *pwm, int duty_ns,
int period_ns);
//使能pwm
int pwm_enable(struct pwm_device *pwm);
關閉pwm
int pwm_enable(struct pwm_device *pwm);

#include #include #include #include #include #include #include #include #include #define hz_to_nanoseconds(x) (1000000000ul/(x))

struct pwm_beeper ;
struct pwm_beeper *beeper;
static int beep_open(struct inode *inode, struct file *fp)
static ssize_t beep_read (struct file *fp, char __user *user_buf, 
size_t count, loff_t *position)
static ssize_t beep_write(struct file *fp, const char __user *user_buf,
size_t count, loff_t *position)
ret = copy_from_user(&beepev, user_buf, sizeof(struct input_event));
if(ret<0)
if (beepev.type != ev_snd || beepev.value < 0)
return -einval;
if (beepev.value == 0)
else
ret = pwm_enable(beeper->pwm);
if(ret)
} 
return 0;
}static int beep_close (struct inode *inode, struct file *fp)
return 0;
}const struct file_operations beepfops =;
struct miscdevice beepmisc=;
static int pwm_beeper_probe(struct platform_device *pdev)
misc_register(&beepmisc);
//platform_set_drvdata(pdev, beeper);
return 0;
}static int pwm_beeper_remove(struct platform_device *pdev)
kfree(beeper);
return 0;
}static int __maybe_unused pwm_beeper_suspend(struct device *dev)
static int __maybe_unused pwm_beeper_resume(struct device *dev)
return 0;
}static ******_dev_pm_ops(pwm_beeper_pm_ops,
pwm_beeper_suspend, pwm_beeper_resume);
#ifdef config_of
static const struct of_device_id pwm_beeper_match = ,
,};module_device_table(of, pwm_beeper_match);
#endif
static struct platform_driver pwm_beeper_driver = ,
};module_platform_driver(pwm_beeper_driver);
module_author("lars-peter clausen ");
module_description("pwm beeper driver");
module_license("gpl");
module_alias("platform:pwm-beeper");

#include#include#include#include#include#include#includeint main(int argc, char **ar**)

beep_evn.type = ev_snd;
beep_evn.code = snd_tone;
beep_evn.value = 2000;
while(1)
close(fd);
return 0;
}

beep ;

圖中inverter off代表正常極性，正常極性表示定時器計數值大於比較值同道輸出高電平，否則輸出低電平，反向極性則相反。

&pwm ;

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