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Interface Buzzer with STM32 || Play a Melody
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Jul 13, 2024
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0:01
[Music]
0:09
hello and welcome to controllers Tech in
0:12
today's video we will see how to
0:15
interface a passive buzzer module with
0:17
the stdm
0:18
32 we will write functions to set the
0:21
tone of the desired frequency and in the
0:23
end we will play A Melody there are two
0:26
types of buzzer modules available for
0:28
interfacing
0:30
an active buzzer is only capable of
0:32
producing a single tone so to interface
0:35
an active buzzer you just need to turn
0:37
the signal on or off just how you would
0:40
blinker LED on the other hand a passive
0:43
buzzer needs a triggered wave to produce
0:46
Sound by controlling the frequency and
0:49
duty of the wave we can control the
0:51
sound output in today's tutorial we will
0:55
cover how to do this using the SDM 32
0:58
MCU here here I have two different types
1:01
of passive buzzer modules with me both
1:04
of these modules have three pins
1:06
available but the middle pin in this
1:09
module is not connected so we only have
1:12
a signal pin and a ground pin it does
1:15
not need a separate VCC Supply we can
1:18
connect the pwm output to this signal
1:21
pin and then vary the frequency and duty
1:23
to control the output sound the other
1:26
module has all three pins connected you
1:30
can connect the VCC to 5 Vols ground to
1:33
ground and pwm output to the io pin both
1:37
of these modules are available on the
1:39
controller's tech store so you can
1:42
purchase them from there I am going to
1:45
use the black one in this tutorial as it
1:47
needs only two pins for the connection
1:50
this is how the buzzer is connected to
1:52
the SDM
1:53
32 the pin pa8 of the MCU is the timer 1
1:58
pwm output pin and it is connected to
2:01
the signal pin let's start the QBE ID
2:05
and create a new project I am using SDM
2:09
32 f103
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C8 give some name to the project and
2:15
click finish let's start with the clock
2:18
setup first I am selecting the external
2:21
Crystal to provide the clock the blue
2:24
pill board has 8 MHz Crystal on it and
2:27
we will run the system at 60 MZ
2:31
I am choosing 60 because most of the SDM
2:33
32 MCU can run at this clock frequency
2:37
so if you have some confusion you can
2:39
set the clock as for this
2:41
video note that both apb1 and two timer
2:44
clocks are running at 60
2:47
mahz the timer will use this clock to
2:50
generate the output signal each timer is
2:53
either connected to apb1 or apb2 bus you
2:57
can check the data sheet of your MCU to
2:59
confirm which bus it is connected to I
3:02
have already made a video explaining the
3:04
pwm generation in SDM 32 you can check
3:08
it out in case of any doubt since both
3:11
the APB timer clocks are at the same
3:14
frequency I don't need to worry about
3:16
the timer's
3:17
Source now go to CIS debug and enable
3:21
serial wire let's configure the timer
3:25
now I am using the timer one to generate
3:28
the pwm signal set the clock source to
3:32
internal clock now enable the pwm
3:35
generation for channel 1 you can see the
3:38
pin pa8 got configured as the pwm output
3:42
we connected this pin to the buzzer in
3:44
the connection
3:46
diagram let's configure the parameters
3:48
now in order to generate the sound of
3:51
desired frequency we need to change the
3:54
prescaler on the fly but keep the a
3:57
constant the timer clock is is at 60
4:01
mahz let's say if I keep the auto reload
4:04
value constant at
4:06
1,000 now if I want to generate a
4:08
frequency of 15 khz the prescaler should
4:12
be set to four similarly if we want to
4:15
generate the frequency of 250 htz the
4:18
prescaler should be set to
4:20
240 we will write a formula in the main
4:23
code to calculate the prescaler for
4:25
desired
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frequency so let's leave the prescaler
4:29
to Zer for now and set the auto reload
4:32
value to
4:33
1,000 we will not modify the duty cycle
4:36
throughout this video rather we will
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keep it at
4:40
50% so set the pulse value to half of
4:43
the auto reload value so the duty can be
4:46
50% that is all the configuration we
4:49
need click save to generate the project
4:53
let's start with a simple test first in
4:56
the main function we will start the
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timer in the pwm mode the parameters of
5:02
this function are the timer Handler and
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the timer Channel which you have
5:07
selected in the cube MX in the cube MX
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configuration we set the prescaler to
5:13
zero so the timer will run at 60
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khz so before starting the timer we will
5:19
set the prescaler to
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240 this will generate a frequency of
5:24
250 HZ actually this value should be 2
5:30
39 whenever you are setting the
5:32
prescaler the value should be one lower
5:35
than the desired value this is because
5:37
the code at the register level adds a
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one to this
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value I will fix this in the final code
5:44
and also mention it in the
5:46
article all right the code has been
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flashed successfully and now you can
5:50
hear the sound produced by the
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buzzer now if I set the prescaler to 24
6:01
the frequency will be
6:03
2,500
6:05
htz Let's test this
6:16
frequency you can clearly hear the sound
6:18
with a higher pitch than
6:20
before let's change these frequencies in
6:23
the while loop so that we can hear the
6:25
differences between them
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you can hear the tone changing every 500
6:39
milliseconds let's also see the output
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on the second
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buzzer we pretty much got the same tones
6:53
in this buzzer
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also a note is produced by managing
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these frequencies and their timing
7:00
we will also do the same and try to
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produce a random Melody we need a
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function to calculate the prescaler
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value for the desired
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frequency let's first Define the timer
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frequency you can change it as per your
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setup the argument of the function
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prescaler for frequency is the desired
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frequency which you want to
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Output inside this function we will use
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the same formula which we have used so
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far to C calculate the
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prescaler the return the calculated
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value in case the frequency is zero we
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don't want to pass the value to the
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formula so we will simply return zero
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now inside the while loop I am
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generating the output at different
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frequencies there is a delay of 250
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milliseconds between each
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tone let's build and Flash the code to
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our board
8:09
you can hear the tones of five different
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frequencies and the pitch is gradually
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increasing and in a way we just produced
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a note of these
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tones basically you can produce any
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Melody by mixing different frequencies
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and their duration for which they will
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play while I was looking for some
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frequency data for a Melody I found this
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GitHub repository this is actually
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written for the Arduino but we are only
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interested in the frequency and timing
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data here this guy has also explained
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how to generate the data for any desired
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music but it is a paid service so I am
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not covering that inside the Arduino
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code I found the data for The Stranger
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Things Melody any Melody will contain
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these two data at minimum the frequency
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and the timing
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let's copy them in our code these here
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are the frequency values for different
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tones and below are their duration in
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milliseconds for which these tones will
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play there is one more parameter which
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is used in the Arduino while playing
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these Melodies and that is the delay
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after the tone for which the tone is
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paused we will also consider this delay
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in our code let's write a function which
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will play the melody for us the
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parameters of this function are the
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pointer to the frequency array the
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pointer to the timing array pointer to
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the pause timing array and the size of
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these
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arrays here for each array element we
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will calculate the prescaler value for
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the input
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frequency then get the duration for
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which the tone will play now Define a
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variable to store the pause data if the
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pause arrays passed to the parameter we
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will get the pause
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timing as for the Arduino source code
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this pause timing also considers the
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duration time so we will need to
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subtract it now let's set the prescaler
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value as calculated above and give a
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delay of the duration time but if we do
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want to pause the tone after this
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duration we will not play any tone after
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this time and it will continue to pause
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for the pause time calculated above we
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will Define this note tone
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function inside this function we will
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set the prescaler to
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zero this will actually generate the
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output frequency of 60 khz which we
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can't hear so it will be treated as the
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pause let's call this function in the
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main function and pass the
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parameters there is no pause data here
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so pass the null here also we need to
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calculate the size of the array
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after the melody is over we will call
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the no tone function to stop the tone
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all right let's Flash the code to the
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board you can hear the stranger things
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Melody being played by the buzzer to
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demonstrate the use of the pause let's
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set the pause time of 30 milliseconds
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after each
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tone you can clearly hear the pause
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between the tones here this is it for
11:54
the video so we were able to interface
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the passive buzzer module with the stdm
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32 we produced the sound of desired
12:03
frequencies and also played a Melody
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successfully you can try some other
12:08
Melodies and let me know the outcome the
12:11
link to download the code is in the
12:13
description below leave comments in case
12:16
of any doubt keep watching and have a
12:20
nice day ahead