Buzzer (buzzer)

Buzzer control interface, supports frequency control and async beep patterns.

Device Type

DEVICE_TYPE_BUZZER

Structure

struct buzzer_t {
    char * name;
    void (*set)(struct buzzer_t * buzzer, int frequency);
    int (*get)(struct buzzer_t * buzzer);
    void * priv;
};

Core API

Function	Description
search_buzzer(name)	Find a buzzer by name
search_first_buzzer()	Find the first buzzer
register_buzzer(buzzer, drv)	Register a buzzer
unregister_buzzer(buzzer)	Unregister a buzzer
buzzer_set_frequency(buzzer, frequency)	Set buzzer frequency (0 to disable)
buzzer_get_frequency(buzzer)	Get current frequency

Async API

Async buzzer control based on thworker_t thread work queue.

struct buzzer_async_ctx_t {
    struct buzzer_t * buzzer;
    struct thworker_t * worker;
};

Function	Description
buzzer_async_ctx_alloc(name)	Allocate an async context, uses first buzzer if name is NULL
buzzer_async_ctx_free(ctx)	Free an async context
buzzer_async_ctx_clear(ctx)	Clear pending tasks and stop buzzer
buzzer_async_beep(ctx, frequency, millisecond)	Async beep at specified frequency for specified milliseconds
buzzer_async_play(ctx, rtttl)	Play RTTTL melody asynchronously

RTTTL Format

RTTTL (RingTone Text Transfer Language) is the Nokia ringtone format. Example:

Simpsons:d=4,o=5,b=160:32p,c.6,e6,f#6,8a6,g.6,e6,c6,8a,8f#,8f#,8f#,2g

Format: <name>:<control>:<tones>. Control fields: d=default duration, o=default octave, b=BPM.

Drivers

buzzer-gpio

GPIO-based buzzer driver.

Required properties:

• gpio: buzzer attached pin

Optional properties:

• gpio-config: gpio pin configuration
• active-low: low level for active buzzer

Example:

"buzzer-gpio": {
    "gpio": 0,
    "gpio-config": -1,
    "active-low": true
}

buzzer-pwm

PWM-based buzzer driver.

Required properties:

• pwm-name: buzzer attached pwm

Optional properties:

• pwm-polarity: pwm polarity

Example:

"buzzer-pwm": {
    "pwm-name": "pwm.0",
    "pwm-polarity": false
}