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#1.2 STM32F103 Clock Setup using REGISTERS || TIMER Config || GPIO Config
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Mar 6, 2021
Purchase the Products shown in this video from :: https://controllerstech.store ________________________________________________________________________________________ Clock Setup in STM32F4 :::: https://youtu.be/GJ_LFAlOlSk STM32 REGISTERS PART2 :::: https://youtu.be/iImNVKJCq4Q STM32 REGISTER Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8ghc4eFhI84z_3p3Ap2MCMV- STM32 Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8gga7xeUUJ-bRUbeChfTOOBd DOWNLOAD THIS PROJECT FROM :::: :::: https://controllerstech.com/stm32f103-clock-setup-using-registers/ ________________________________________________________________________________________ ******* SUPPORT US BY DONATING****** https://paypal.me/controllertech *******Join the Membership******* https://www.youtube.com/channel/UCkdqtSMnhYuMsJkyHOxiPZQ/join
View Video Transcript
0:11
[Music]
0:18
hello everyone
0:20
welcome to another video of controllers
0:23
tech
0:24
after i made some videos of register
0:26
programming with stm32f4 series a lot of
0:30
you guys requested the same for the f103
0:33
also
0:35
blue pill is a very popular device from
0:37
st
0:38
so i have decided to create a video for
0:40
the basic setup on stm32f103
0:45
this video will cover the basic clock
0:47
setup and timer setup
0:49
for the delay in micro and milliseconds
0:52
i can't continue making separate videos
0:55
for different microcontrollers for each
0:57
topic
0:58
so i will just continue making videos
1:00
for f4 series
1:01
but i will also include the code for
1:03
f103 in the final download
1:07
mostly the things will be same but i
1:09
will comment the code properly
1:11
for better understanding so today we
1:14
will cover the clock setup and the timer
1:16
setup to create
1:17
delays so let's start by creating a new
1:21
project in kyle id
1:24
give some name to the project and click
1:27
finish
1:29
select the controller here now we will
1:40
only select the cmsis core
1:42
and the device startup files from here
1:46
[Music]
1:53
let's first add the main file to this
1:55
project
2:01
inside this main file i am creating the
2:04
main function
2:05
and a while loop so this completes the
2:08
basic setup
2:10
now first of all we will include the
2:13
device header file
2:20
if you see inside the file here you have
2:22
all types of registers
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interrupts and pretty much everything is
2:26
defined here
2:40
before going forward let's include the
2:48
libraries
2:50
copy them inside the project folder
3:02
and inside the project add those files
3:09
you can see the files got added here
3:12
this delay header file have these
3:14
functions that we can use anywhere in
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our main file
3:22
we will talk about them in a while let's
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include the delay header file in our
3:30
main
3:34
now we will set up the clocks first
3:40
this process was quite difficult in f4
3:42
series
3:43
but here it's pretty simple we just need
3:46
to call this function
3:48
system init and we are done
3:53
let's see what's going on inside it
4:00
so system in it is predefined in the
4:02
core files
4:03
that we included in our project it does
4:06
all the operations that we did in that
4:08
f4 series video
4:16
even though everything is predefined you
4:18
still have some control over the clocks
4:21
if you go to the top of this page here
4:24
you see the different clocks are defined
4:32
you can uncomment the clock that you
4:34
want to set
4:36
by default it is 72 megahertz and this
4:39
is the maximum clock that blue pill can
4:41
run
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with i am okay with this setup
4:45
and i will leave it as it is note here
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that
4:48
if you comment out every clock then the
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system will run at internal clock
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also known as hsi high speed internal
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oscillator
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so choose the clock according to your
5:00
requirement
5:02
if you want any other setup other than
5:04
these predefined ones
5:05
you need to follow my other video in
5:08
which i covered the clock setup for f4
5:10
series
5:11
the steps will be same with minor
5:13
changes of course
5:15
this is it for the clock setup now
5:18
before going into timer setup
5:20
let's see the clocks with cube mx once
5:46
this is how the current clocks are
5:48
configured
5:49
we will come back to this
6:02
now let's see the delay.c file
6:06
as you can see here i am using timer 2
6:09
to create delays
6:11
here are the steps given to configure
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the timer
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we need to enable the timer 2 clock
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first
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then according to the requirement set
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the prescaler
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and the auto reload register values
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and finally enable the timer and wait
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for the confirmation
6:31
let's take a look at them now in order
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to enable the timer clock
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we need to see the rcc register
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to be precise rcc apd1 enable register
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here you can see the bit zero of this
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register enables the timer two clock
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so that's what i did i am writing a one
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in the zeroth position
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these commented lines here are the
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default setup for timer
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as they all are zeroes we don't need to
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write them
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but anyway i have commented the code so
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that you can understand what they mean
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now we need to set the prescaler and
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auto reload register
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prescaler divides the timer clock and it
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is used to reduce the frequency of high
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peripheral clocks to whatever working
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range you want
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before setting the prescaler we need to
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understand the clocks
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basically the timers are connected to
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the peripheral plots
7:48
blue pill have two peripheral clocks
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apb1
7:52
and apb2 as you can see here
7:56
the apb1 timer clock is running at 72
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megahertz
8:00
and so does the apb b2 timer clock
8:04
since all the timers are connected to
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these clocks
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all the timers will also be running at
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72 megahertz
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but this is too convenient what if you
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have some different setup here
8:17
to know the timer clock you need to know
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where the timer is connected
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to know that look at the data sheet for
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your device
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and there you will see this clock
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diagram
8:28
as you can see here the timer 1 is
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connected to the apb 2 clock
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and timer 2 is connected to the apb1
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clock
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similarly you can see the other timers
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also
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as i am using timer 2 which is connected
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to the apb1
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and which is running at 72 megahertz
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this means my timer clock is also 72
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megahertz right now
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now a prescaler of 72 will further
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divide this clock
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and bring it down to 1 megahertz
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we need to write -1 here and the reason
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can be seen in the reference manual
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let's understand the auto-reload
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register
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so when we enable the timer the counter
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starts counting from zero
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since i have set up the timer clock at
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one megahertz
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each count of this counter will take one
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microsecond
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this counter will continue counting and
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the maximum count that can reach is the
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auto reload register value
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so this is why we need to set the
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maximum value for the arr
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so that our counter can avoid reaching
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that value
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now we will enable the timer and wait
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for the update flag to set
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in order to enable the timer we need to
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look in the control register 1.
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as you can see the zeroth bit of cr1
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register enables the timer counter
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so we need to write a 1 in the 0th
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position
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for the update flag we will check the
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status register
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bit 0 is the uif bit
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and you can see this bit is set when the
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content of the register are
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updated
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so we will wait for this bit to set this
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completes the timer configuration
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now this function here is the function
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to generate the delay in microseconds
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basically we will set the counter to
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zero and wait for the counter to reach
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the entered value
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as i have already mentioned that our
11:13
setup is in such
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a way that each count takes 1
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microsecond so this will result as delay
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in desired microseconds
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now let's talk about the gpio
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configuration
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i will blink the on-board led and to do
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that we need to set the pin as output
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we all know the led is connected to pin
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pc13
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[Music]
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the steps are very simple enable the
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gpioc
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clock and configure the pin as output
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pin
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let's enable the gp io clock first
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we need to go back to our cc registers
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as you can see in the apb2 enable
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register
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4th bit controls the port c clock
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to enable the gpioc clock
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we will write a one in the fourth
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position
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next step is to configure the pin as
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output
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and to do so we will go to the gpio
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registers
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[Music]
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the first one here is the port
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configuration register
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this register is responsible for
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configuring the mode of the pin
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and its type as you can see here
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the first two bits set the mode for the
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pin and the next two bits configure that
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mode similarly the next four bits
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controls pin one mode
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and its configuration this register is
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divided into two parts
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control register low is responsible for
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controlling bits 0 to 7
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and since we are using pc13 we will go
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to the control register high
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[Music]
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here we will set the output mode
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you can choose the speed according to
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the requirement
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i am choosing 10 megahertz speed
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so in order to set the pin 13 as output
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we need to write 0 and 1 to the 21st and
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20th positions
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basically write a 1 at the 20th position
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in the crh
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register
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now for the configuration we are using
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output mode
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so these will be valid
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i am choosing push-pull type output as
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it's better for blinking a led
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so i need to write zeros in the 22nd and
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23rd positions
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these positions are zero by default so i
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am not writing anything there
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then we have port bit set or reset
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register
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which we will come to in a while this
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completes the configuration for the gpio
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now let's write our main function first
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of all call the gpio config
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then call the timer config now inside
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the while loop
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we will turn the led on and off
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to do that we need to see the bsr
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register
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this register is divided into two halves
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bits 0 to 15 can be used to set the pin
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and 16 to 31 can be used to reset the
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pin
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since we are interested in pin 13 in
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order to set this pin
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we need to write a 1 in the 13th
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position and to reset the pin
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we need to write a 1 in the 29th
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position
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let's set this pin pc13
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now we will give some delay here
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i will use this delay m s function to
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set the delay in milliseconds
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set the 1 second delay now reset pc
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13 by writing a 1 in the 29th position
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and give 1 second delay again
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this is it let's build it now
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we don't have any errors before
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uploading
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make sure you make changes in the
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options here
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let's upload it now
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as you can see the led is blinking every
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one second
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this means the clock setup the timer
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setup and the gpio
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setup everything went well this wraps up
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the basic configuration needed for the
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blue pill
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you can use the same configuration in
17:13
other videos as well
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i will continue making these videos for
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f4 series
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but i will upload the code for blue pill
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also
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if there are too many changes in the
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process i will make a separate video for
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blue pill for that particular peripheral
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you can support this channel by joining
17:32
the membership
17:33
plan the download link for this
17:36
code is in the description that's all
17:40
for this video
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keep watching and have a nice day ahead
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