Buzzer
Drive a buzzer or speaker using the PWM API.
Overview
This is a sample app which drives a buzzer or speaker using the PWM API.
The sample plays a short beep with 1108.73 ㎐ (music note D♭₆ [1]) for the time of a ⅛ music note [2] at boot time and offers the special shell command buzzer for playing other jingles or short songs.
Requirements
The sample requires a buzzer or speaker whose signal pin is connected to a pin
driven by PWM. The buzzer or speaker must be defined in Devicetree using the
pwm-buzzers
compatible (part of the sample) and setting its node to the
alias pwm-buzzer0
. You will need to do something like this:
/ {
aliases {
pwm-buzzer0 = &pwm_buzzer0;
};
pwm_buzzers {
compatible = "pwm-buzzers";
status = "okay";
pwm_buzzer0: pwm_buzzer0 {
pwms = <&pwm0 1 PWM_HZ(880) PWM_POLARITY_NORMAL>;
label = "PWM_BUZZER";
};
};
};
Note that a commonly used period value is 880 ㎐, twice the concert pitch frequency of 440 ㎐. See one of the following development boards:
Building and Running
On Maker Nano RP2040 board:
west build -b cytron_maker_nano_rp2040 -p -d build/buzzer-cytron_maker_nano_rp2040 bridle/samples/buzzer west flash -r uf2 -d build/buzzer-cytron_maker_nano_rp2040
On Maker Pi RP2040 board:
west build -b cytron_maker_pi_rp2040 -p -d build/buzzer-cytron_maker_pi_rp2040 bridle/samples/buzzer west flash -r uf2 -d build/buzzer-cytron_maker_pi_rp2040
Sample Output
[00:00:00.003,000] <inf> buzzersh: Buzzer shell is ready!
uart:~$ <Tab>
bridle buzzer clear device devmem gpio help
history kernel log pwm rem resize retval
shell
uart:~$ help
Please press the <Tab> button to see all available commands.
You can also use the <Tab> button to prompt or auto-complete all commands or its subcommands.
You can try to call commands with <-h> or <--help> parameter for more information.
Shell supports following meta-keys:
Ctrl + (a key from: abcdefklnpuw)
Alt + (a key from: bf)
Please refer to shell documentation for more details.
Available commands:
bridle :Bridle commands.
buzzer :Buzzer related commands
clear :Clear screen.
device :Device commands
devmem :Read/write physical memory
Usage:
Read memory at address with optional width:
devmem address [width]
Write memory at address with mandatory width and value:
devmem address <width> <value>
gpio :GPIO commands
help :Prints the help message.
history :Command history.
kernel :Kernel commands
log :Commands for controlling logger
pwm :PWM shell commands
rem :Ignore lines beginning with 'rem '
resize :Console gets terminal screen size or assumes default in case the
readout fails. It must be executed after each terminal width change
to ensure correct text display.
retval :Print return value of most recent command
shell :Useful, not Unix-like shell commands.
uart:~$ buzzer -h
buzzer - Buzzer related commands
Subcommands:
info :Get buzzer info
beep :Use buzzer to beep
play :Play one of predefined sounds
uart:~$ buzzer info
Warning: not yet implemented.
uart:~$ buzzer beep
uart:~$ buzzer play
play - Play one of predefined sounds
Subcommands:
folksong :Play the 'folksong' song
xmastime :Play the 'folksong' song
funkytown :Play the 'funkytown' song
mario :Play the 'mario' song
golioth :Play the 'golioth' song
tiacsys :Play the 'tiacsys' song
uart:~$ buzzer play folksong
uart:~$ buzzer play xmastime
uart:~$ buzzer play funkytown
uart:~$ buzzer play mario
uart:~$ buzzer play golioth
uart:~$ buzzer play tiacsys