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#1. Intro to STM32F4 Register Based Programming || Clock Setup || LED Blinking || NO HAL
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Aug 11, 2020
Purchase the Products shown in this video from :: https://controllerstech.store ________________________________________________________________________________________ STM32 REGISTERS PART2 :::: https://youtu.be/iImNVKJCq4Q Clock Setup in F103 :::: https://youtu.be/Ke_jD_2ILMU 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/stm32-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
0:01
[Music]
0:09
hello
0:10
everyone welcome to controllers tech
0:14
this video is the start of a new series
0:16
and in this series i will cover the
0:18
stm32 register level programming
0:22
this is the first video and today we
0:24
will see how to set up the clock
0:27
and that's why this video is going to be
0:29
very long
0:31
there are no shortcuts here some
0:33
registers and values might be different
0:35
for your controller
0:36
and that's why you need to see the
0:38
entire process
0:40
i will use kyle for these tutorials
0:44
let's open the pack installer first
0:47
type your mcu name and let it refresh
0:50
the database
0:58
now you need to install the dfp pack
1:01
from here
1:02
that will be all you need
1:07
also make sure the compiler is updated
1:11
i already have them installed and
1:13
updated
1:24
go to project and create a new project
1:33
give the name to this project and click
1:38
save
1:47
search for your device here
1:53
[Music]
1:58
we only need to include the core file
2:01
and startup
2:02
file from here
2:08
here is our project let's add the main
2:11
file to this
2:19
first of all include the device specific
2:22
file
2:24
[Music]
2:27
this file have all the registers irq
2:30
predefined in it
2:36
i am going to create a main function and
2:38
a while loop inside it
2:44
let's create a function where we will
2:46
configure the clock
2:50
and here are the steps that i am going
2:52
to follow
2:54
first we need to enable the external
2:56
crystal
2:57
and wait for it to become ready then
3:00
enable the power
3:01
and configure the voltage regulator
3:04
next we need to configure the flash
3:07
related settings
3:09
then configure the prescalers for
3:11
peripheral clocks
3:13
then configure the pll then enable the
3:17
pll
3:18
and finally select the pll as the clock
3:20
source
3:25
we will cover all these steps one by one
3:29
let's also open the cube mx for the
3:44
reference
3:59
i am selecting external crystal for the
4:01
clock
4:03
i will configure for the maximum clock
4:05
here because i always prefer it
4:07
and this way i can keep the same
4:09
settings for the other programs too
4:23
we will come back to this once we start
4:26
programming
4:33
let's start with the first step
4:36
so we need to turn the hse on
4:40
and wait for it to become ready
4:44
this bit is in the rcc cr register
4:53
as you can see here the 16th bit is for
4:56
hse on
4:57
and the 17th bit is the hse ready bit
5:07
in the rcc cr register set the hse
5:12
on bit
5:13
[Music]
5:18
this is already defined in the header
5:20
file and it's basically writing a 1
5:23
at 16th position now we will wait for
5:26
the hse ready bit
5:28
to set in the cr register
5:30
[Music]
5:35
this will indicate that the hse crystal
5:38
is on
5:39
let's move to the second step enable the
5:43
power interface clock
5:44
and configure the voltage regulator
5:55
power enable is 28th bit of the rcc apb1
6:04
register
6:12
we will set this bit in order to enable
6:15
[Music]
6:18
it now the setting for the voltage
6:21
regulator
6:24
[Music]
6:31
this bit is located in power control
6:33
register
6:34
and it's the bit number 14 and 15.
6:43
just keep this to its reset value in
6:45
this case it will be 1
6:47
1.
6:57
the vos will always correspond to the
6:59
reset value
7:06
now the step 3 we need to configure the
7:10
flash related setup
7:12
to do so we need to modify the flash
7:15
access control
7:16
register
7:20
let's see the cube mx here we have all
7:24
instruction cache
7:25
prefetch buffer data cache all are
7:28
enabled
7:29
and the flash latency is 5ws
7:40
all these bits are available in access
7:42
control register
7:51
let's set the flash acr register
7:56
accordingly
8:10
do
8:12
now the fourth step is to configure the
8:14
prescalers for the main clock
8:16
and the peripheral clocks
8:26
as you can see here apb1 prescaler is 4
8:30
apb2 prescaler is 2 and ahb prescaler is
8:34
[Music]
8:38
1.
8:43
all these configuration bits are in our
8:45
cc clock configuration register
8:59
let's first set the ahb prescaler
9:03
ahb prescaler is one in our setup
9:06
so i am using division 1.
9:14
next set the abp1 prescaler which have
9:18
the value 4
9:19
so division 4.
9:29
and at last set the apd2 prescaler
9:32
whose value is 2 and that's why division
9:35
2.
9:36
let's move to the fifth step and
9:38
configure the pll
9:46
we will do that by modifying the rccpll
9:50
configuration register here we need to
9:53
set the values of pllm
9:55
and plln p q and r
10:06
you can see the values here pllm is for
10:10
plln is 180
10:13
and pllp is 2.
10:29
let's define these values first
10:49
in the pllm we can directly input the
10:52
value at the bit 0.
10:54
similarly in plln we can input the value
10:58
at bit 6 directly
11:05
but in pllp we can't directly use the
11:08
values
11:09
as we need to select from these
11:11
available here
11:12
i have the pllp as 2 so i need to write
11:16
0 to this 16th position
11:24
so i will simply shift this 0 to the
11:27
sixteenth position
11:35
let's modify the pll configuration
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register now
11:40
p l l m starts at bit zero
11:44
p l l n starts at bit six
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p pllp starts at bit 16.
11:58
here we also need to select the source
12:00
of pll
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which in this case is hse oscillator and
12:05
i need to write a 1 a 22nd bit
12:20
in step 6 we need to enable the pll
12:32
in our cc control register bit 24
12:35
enables the pll
12:37
and bit 25 confirms the ready status
12:49
let's enable the pll first and now we
12:52
will wait for the pll to become ready
13:03
the final step is to set the clock
13:05
source
13:10
this can be done in the rcc
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configuration register
13:15
the zeroth bit is to set the clock
13:17
source and the second bit is to confirm
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the status
13:21
here i will use the pllp as the clock
13:24
source
13:26
set the pll as the clock source
13:30
and wait for the source to become ready
13:42
this completes the clock setup now from
13:46
now onward
13:47
in most of these videos i will use these
13:49
settings as it is
13:52
so this was basically just a one-time
13:54
setup
13:57
[Music]
13:58
now as we want to blink the led we need
14:01
to configure the gpio
14:05
here the things are easy just enable the
14:08
gpio clock
14:10
set the pin as output and configure any
14:12
settings you need for the output mode
14:16
let's start with the first one to enable
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the gpio clock
14:21
we need to look into a cc peripheral
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clock enable register
14:26
as you can see here the zeroth bit of
14:29
this register
14:30
enables the gpio clock
14:37
by the way i am using pin pa5 for the
14:40
led
14:43
write a one to the zeroth position to
14:45
enable the clock for gpioa
14:49
in the second step we'll set the pin as
14:56
output
14:58
this can be done using gp io mode
15:01
register
15:06
here we need to write a 0 and 1 to set
15:09
the pin as output
15:12
every two bits of this register controls
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a single pin
15:16
for example bits 0 and 1 controls the
15:20
pin 0
15:21
bits 2 and 3 controls the pin 1 bits 4
15:24
and 5
15:24
controls the pin 2 and similarly bits 30
15:28
and 31
15:29
controls the pin 15. as i need to set
15:33
the pin
15:33
5 as the output i need to modify bits 10
15:36
and 11 so 11th bit will be 0 and 10th
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bit will be 1.
15:49
in the gpioa mode register
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i will write a 1 in the 10th position
15:55
and 11th position is 0 by default
16:02
now the last step is to configure the
16:04
output mode
16:06
like what type of output we want
16:09
default setup is for push-pull and this
16:11
is exactly what we need
16:19
then we have the type of speed we want
16:21
for the output pin
16:23
by default its low speed i am okay with
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it
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since i am only blinking led for now
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the there is pull up or pull down
16:32
configuration
16:34
we will leave this to none since we are
16:36
using the pin
16:37
for blinking so all the remaining
16:40
registers should be zero
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even if you don't write values to them
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they will be zero by default
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i will write them anyway
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this finishes up the gpio configuration
16:56
let's write the main function now
16:59
first of all set the system clock and
17:02
then set the gpio
17:05
and now on the while loop i need to
17:07
toggle the pin pa5
17:10
to set or reset a pin we need to use the
17:13
gpio bit set reset register
17:17
as you can see here to set a pin we need
17:20
to set it in the lower half of the
17:22
register
17:24
and in order to reset the pin we need to
17:26
write a 1
17:27
in the upper half
17:32
as i am setting pin p-a-5 i will write
17:35
the fifth bit of this register to 1.
17:38
let's give some delay which i will cover
17:41
later
17:42
now to reset the pin 5 i need to write a
17:45
1 to the upper half of this register
17:48
as you see here the upper half starts at
17:51
bit 16
17:52
so the pin 5 will be the 21st bit and to
17:55
reset it
17:56
i need to write a 1 in 21st position
18:00
instead of doing that i will simply
18:02
write a 1 to the 5th position
18:04
and shift the entire value by 16 places
18:08
and again give the delay for toggling
18:11
let's create that delay function
18:15
this is just some random wait time
18:18
let's build this
18:19
[Music]
18:23
we don't have any errors here go to
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options
18:27
and update the frequency here mind will
18:30
be running at 180 megahertz
18:34
select the st link debugger
18:39
select connect under reset
18:44
and reset and run
18:45
[Music]
18:49
click download to flash the code
18:56
you can see the led is blinking but it's
18:59
too fast to be noticed
19:01
[Music]
19:04
let's increase the delay
19:12
[Music]
19:18
now the blinking is perfect
19:26
let's modify it one last time
19:42
and you can see now it's even more
19:44
slower
19:49
so that's all for this video i will
19:53
continue this series
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and we will cover all sort of
19:56
peripherals here
19:58
also a cc was just one time setup
20:01
and next video onward i will simply
20:04
include it in the main file directly
20:06
i hope you learned something today
20:09
things can be a bit hard in the
20:11
beginning especially if you have never
20:13
worked with registers before
20:16
but you have to start somewhere in the
20:19
next video
20:20
i will cover the basic feature of the
20:22
timer and we will use it to generate the
20:24
proper time delay
20:26
goodbye till then keep watching and have
20:29
a nice day
20:38
you
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