Buzzer/en: различия между версиями

Материал из Wiren Board
(Новая страница: «==Management from web interface==»)
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{{DISPLAYTITLE:Зуммер (звуковой излучатель)}}
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{{DISPLAYTITLE:Buzzer}}
==Description==
==Description==
The Wiren Board controller has a Buzzer (sound emitter) on board. The buzzer is powered by 5V and controlled by the CPU's gpio pin in PWM mode. The buzzer can be controlled through the sysfs interface of the kernel and various software on top of it. Also, it can be controlled via the web interface, the wb-rules rule engine and python.
The Wiren Board controller has a Buzzer (sound emitter) on board. The buzzer is powered by 5V and controlled by the CPU's gpio pin in PWM mode. The buzzer can be controlled through the sysfs interface of the kernel and various software on top of it. Management from the web interface, the wb-rules rule engine and python is now implemented.


==Controlling via web-interface==
==Management from web interface==


[[File:buzzer.png |300px|thumb|right| Buzzer control]]
[[File:buzzer.png |300px|thumb|right| Buzzer control]]
In the web-interface of the controller, buzzer control is available in the ''"Devices"'' tab. Parameter ''"Frequency"'' - sound frequency in Hz. ''"Volume"'' - volume (in conventional units, linear scale). The settings are saved when the controller is rebooted.
In the web interface of the controller, buzzer control is available in the ''"Devices"'' tab. Parameter ''"Frequency"'' - sound frequency in Hz. ''"Volume"'' - volume (in conventional units, linear scale). The settings are saved when the controller is rebooted.


==Controlling via rule engine==
==Control from rule engine==




The buzzer control displayed in the web interface is a virtual device created by the wb-rules system rule when the controller starts. The source code of the rule is available [https://github.com/wirenboard/wb-rules-system/blob/master/rules/buzzer.js on our github].
The buzzer control displayed in the web interface is a virtual device created by the wb-rules system rule when the controller starts. The source code of the rule is available [https://github.com/wirenboard/wb-rules-system/blob/master/rules/buzzer.js on our github].


You can learn more about virtual devices usage in the [[wb-rules|description of the rules engine]].
You can learn more about what virtual devices are for in the [[wb-rules|description of the rules engine]].


The system rule internally implements tone and volume recalculation (see [[#About PWM and parameter recalculation|section on recalculation]]) and work with pwm via sysfs (see [[#Working from sysfs|corresponding section]]). Outside, the user has access to the ''"buzzer"'' device, which has several mqtt controls:
The system rule internally implements tone and volume recalculation (see [[#About PWM and parameter recalculation|section on recalculation]]) and work with pwm via sysfs (see [[#Working from sysfs|corresponding section]]). Outside, the user has access to the ''"buzzer"'' device, which has several mqtt controls:
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Device controls can be used in custom rules. More details about the structure of mqtt topics for virtual and physical devices can be found in our [https://github.com/wirenboard/conventions/blob/main/README.md mqtt convention].
Device controls can be used in custom rules. More details about the structure of mqtt topics for virtual and physical devices can be found in our [https://github.com/wirenboard/conventions/blob/main/README.md mqtt convention].


==Controlling via python==
==Control from python==


On Wiren Board controllers, you can work with the buzzer from python using the ''beeper'' module from the ''wb_common'' package. This is a wrapper around the sysfs interface. The module is preinstalled on all controllers as part of the ''python-wb-common'' deb package. The source code is available [https://github.com/wirenboard/wb-common/blob/master/wb_common/beeper.py on our github].
On Wiren Board controllers, you can work with the buzzer from python using the ''beeper'' module from the ''wb_common'' package. This is a wrapper around the sysfs interface. The module is preinstalled on all controllers as part of the ''python-wb-common'' deb package. The source code is available [https://github.com/wirenboard/wb-common/blob/master/wb_common/beeper.py on our github].
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All sysfs interface settings are supported (recalculation must be done manually; see [[#About PWM and parameter recalculation|section on recalculation]]).
All sysfs interface settings are supported (recalculation must be done manually; see [[#About PWM and parameter recalculation|section on recalculation]]).


==Low-level work==
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===About PWM and parameter recalculation===
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[[File:Duty_cycle.gif|440px|thumb|right|Duty cycle controls LED brightness/buzzer volume]]
PWM is a rectangular pulse, the core interface allows you to adjust the pulse rate and fill factor. Coeffecient filling effect on the sound volume.
PWM is a common way to control the power delivered to a load.
</div>


In the context of buzzer control, we are interested in 2 PWM parameters:
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* Duty cycle - affects the volume of the sound. Usually, it is considered as a percentage of the signal period.
Exporting port to sysfs:
* PWM frequency (frequency) - affects the pitch (the higher the frequency, the higher the sound). The unit that is the reciprocal of the signal period.
<pre>
echo 2 > /sys/class/pwm/pwmchip0/export
</pre>
</div>


The Linux kernel provides a sysfs interface to pwm that accepts a pwm frequency and a duty cycle in '''nanoseconds (10<sup>-9</sup>S)'''! Therefore, for low-level control of the Buzzer, it is necessary to recalculate the desired frequency from kHz to a period in nanoseconds using the formula:
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After that, the /sys/class/pwm/pwmchip0/pwm2 folder appears
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Sets the period in nanoseconds. The conversion from frequency(from kilohertz per period in nanoseconds is produced by the formula:
<b>
<b>
T(ns) = 1,000,000 / f(kHz)
T(ns) = 1 000 000 / f(kHz)
</b>
</b>
</div>


===Pwm port number for sysfs===
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<pre>
The gpio pin is configurable like the PWM output in the dts of the linux kernel. For more details, see [[https://github.com/wirenboard/linux/blob/ef2d87e222b365848fe7262c022ca887b6449432/arch/arm/boot/dts/imx6ul-wirenboard61.dts#L495 on our github]].
echo 250000 > /sys/class/pwm/pwmchip0/pwm2/period # set the period to 250 000 NS, ie 250mks, which corresponds to a frequency of 4kHz
</pre>
</div>


*For WB6.X.X controllers, port number = 0, (for all controllers up to WB6.X.X, port number = 2)
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*The port number can be found by running <syntaxhighlight lang="bash">echo $WB_PWM_BUZZER</syntaxhighlight>
Setting the duty_cycle (the duration of the high state) in nanoseconds. Maximum volume is reached at duty_cycle = period / 2
In all examples below, we will assume that the pwm port number = 0.
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===Working from sysfs===
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<pre>
echo 125000 > /sys/class/pwm/pwmchip0/pwm2/duty_cycle #set duty_cycle to 125 000 NS, i.e. in half of the period
</pre>
</div>


To work with pwm through sysfs you need:
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#Export port <syntaxhighlight lang="bash">echo 0 > /sys/class/pwm/pwmchip0/export</syntaxhighlight>After that, the /sys/class/pwm/pwmchip0/pwm0 directory appears
Enable PWM output:
# Write the pwm period in nanoseconds <syntaxhighlight lang="bash">echo 250000 > /sys/class/pwm/pwmchip0/pwm0/period # set the period to 250,000 ns, i.e. in 250µs, which corresponds to a frequency of 4kHz</syntaxhighlight>
<pre>
#Record volume (calculated from duty-cycle) <syntaxhighlight lang="bash">echo 125000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle # maximum volume is reached when duty_cycle = period / 2 => set duty_cycle to 125,000 ns</syntaxhighlight>
echo 1 > /sys/class/pwm/pwmchip0/pwm2/enable
#Enable PWM output <syntaxhighlight lang="bash">echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable</syntaxhighlight>
</pre>
</div>


To turn off the buzzer, write 0: <syntaxhighlight lang="bash">echo 0 > /sys/class/pwm/pwmchip0/pwm0/enable</syntaxhighlight>
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Shutdown:
<pre>
echo 0 > /sys/class/pwm/pwmchip0/pwm2/enable
</pre>
</div>


[https://github.com/contactless/wirenboard/tree/master/examples/beeper '''An example of a bash script for working with pwm''']
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[https://github.com/contactless/wirenboard/tree/master/examples/beeper '''Example''']
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Set the period in nanoseconds. The conversion from frequency (in kilohertz) to period (in nanoseconds) is performed using the formula:
Установка периода в наносекундах. Пересчёт из частоты (в килогерцах) в период (в наносекундах) производится по формуле:
<b>
<b>
T(ns) = 1,000,000 / f(kHz)
T(ns) = 1 000 000 / f(kHz)
</b>
</b>

Версия 20:46, 22 сентября 2022

Другие языки:

Description

The Wiren Board controller has a Buzzer (sound emitter) on board. The buzzer is powered by 5V and controlled by the CPU's gpio pin in PWM mode. The buzzer can be controlled through the sysfs interface of the kernel and various software on top of it. Management from the web interface, the wb-rules rule engine and python is now implemented.

Management from web interface

Buzzer control

In the web interface of the controller, buzzer control is available in the "Devices" tab. Parameter "Frequency" - sound frequency in Hz. "Volume" - volume (in conventional units, linear scale). The settings are saved when the controller is rebooted.

Control from rule engine

The buzzer control displayed in the web interface is a virtual device created by the wb-rules system rule when the controller starts. The source code of the rule is available on our github.

You can learn more about what virtual devices are for in the description of the rules engine.

The system rule internally implements tone and volume recalculation (see section on recalculation) and work with pwm via sysfs (see corresponding section). Outside, the user has access to the "buzzer" device, which has several mqtt controls:

Device Control Type Max value Description
Buzzer Frequency range 7000 Sound frequency
Volume range 100 Volume,%
Enabled Switch Enable/Disable

Device controls can be used in custom rules. More details about the structure of mqtt topics for virtual and physical devices can be found in our mqtt convention.

Control from python

On Wiren Board controllers, you can work with the buzzer from python using the beeper module from the wb_common package. This is a wrapper around the sysfs interface. The module is preinstalled on all controllers as part of the python-wb-common deb package. The source code is available on our github.

Working example from python: 

from wb_common import beeper

beeper.beep(0.5, 2)

All sysfs interface settings are supported (recalculation must be done manually; see section on recalculation).


PWM is a rectangular pulse, the core interface allows you to adjust the pulse rate and fill factor. Coeffecient filling effect on the sound volume.

Exporting port to sysfs: 

echo 2 > /sys/class/pwm/pwmchip0/export

After that, the /sys/class/pwm/pwmchip0/pwm2 folder appears

Sets the period in nanoseconds. The conversion from frequency(from kilohertz per period in nanoseconds is produced by the formula: T(ns) = 1 000 000 / f(kHz) 

echo 250000 > /sys/class/pwm/pwmchip0/pwm2/period # set the period to 250 000 NS, ie 250mks, which corresponds to a frequency of 4kHz

Setting the duty_cycle (the duration of the high state) in nanoseconds. Maximum volume is reached at duty_cycle = period / 2 

echo 125000 > /sys/class/pwm/pwmchip0/pwm2/duty_cycle #set duty_cycle to 125 000 NS, i.e. in half of the period

Enable PWM output: 

echo 1 > /sys/class/pwm/pwmchip0/pwm2/enable

Shutdown: 

echo 0 > /sys/class/pwm/pwmchip0/pwm2/enable

Example

Установка периода в наносекундах. Пересчёт из частоты (в килогерцах) в период (в наносекундах) производится по формуле: T(ns) = 1 000 000 / f(kHz)

Источник — https://wirenboard.com/wiki/index.php?title=Buzzer/en&oldid=68829