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STM32 CAN Communication || NORMAL Mode
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May 22, 2021
Purchase the Products shown in this video from :: https://controllerstech.store ________________________________________________________________________________________ STM32 CAN Filter Configuration :::: https://youtu.be/JfWlIY0zAIc STM32 CAN Multiple Devices :::: https://youtu.be/-lcrrRrKdFg STM32 CAN Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8gjzwOPq9fvQt38Ut7EjsgwI STM32 Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8gga7xeUUJ-bRUbeChfTOOBd DOWNLOAD THIS PROJECT FROM :::: https://controllerstech.com/can-protocol-in-stm32/ ________________________________________________________________________________________ ******* SUPPORT US BY DONATING****** https://paypal.me/controllertech *******Join the Membership******* https://www.youtube.com/channel/UCkdqtSMnhYuMsJkyHOxiPZQ/join
View Video Transcript
0:09
hello
0:09
everyone welcome to controllers tech
0:14
this is part 2 of the tutorial on can
0:16
peripheral and today we will see how to
0:18
communicate between
0:19
two can devices i have already covered
0:22
the basics of the can protocol
0:24
and you must watch that video before
0:26
this one
0:28
you can see the video on the top right
0:31
so let's start with this video now
0:34
i am using the blue pill and the f446re
0:38
controllers
0:39
and the connection is as shown here the
0:42
rx and the tx pins from the transceivers
0:45
are connected to the respective
0:47
microcontrollers
0:48
then can high and can low are connected
0:51
with each others
0:53
note that there must be a 120 ohms
0:56
resistance connected at each node
0:58
just as it is shown in figure some
1:00
transceivers have this resistance on the
1:03
breakout board itself
1:04
and other don't so make sure you check
1:07
the resistance
1:13
here is how the connection is i have
1:16
twisted the wire pair connected between
1:18
can high and can low
1:20
you could try with simple wires but if
1:23
doesn't work
1:24
try twisted pair here is the 120 ohms
1:28
resistance connected between the can
1:30
high
1:31
and low i have it connected on the other
1:34
node too
1:35
p11 and p12 from blue pill are connected
1:38
to the first transceiver
1:40
and the same pins from nucleo are
1:42
connected to the second transceiver
1:45
the transceivers are powered with 5
1:47
volts from the microcontrollers
1:50
this is all about the connection now
1:52
let's start the project for the nucleo
1:54
first
1:59
so here we are in the cube mx
2:03
first of all i am selecting the external
2:06
crystal for the clock
2:08
i have eight megahertz crystal and i
2:10
want the system to run at maximum 180
2:13
megahertz
2:18
notice here that the four four six f2
2:21
can peripherals
2:24
as mentioned in the reference manual the
2:27
can one is the master can
2:29
and the can 2 is the slave can
2:34
also they have 28 filter banks all
2:37
together
2:41
let's configure the can one
2:45
now here i am going to set the board
2:47
rate to 500
2:48
000 bits per second
2:55
i am just modifying these parameters to
2:57
get that
3:06
here i got the board rate
3:11
now make sure that the operating mode is
3:13
set to normal
3:18
and i am going to use fifo zero to store
3:20
the incoming message
3:22
so in the nvic i am enabling the rx0
3:26
interrupt
3:27
this is it for can setup now i am
3:30
setting the pa5 as output for the
3:32
onboard led
3:35
also i am selecting the external
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interrupt for the user button
3:39
which is connected to the pc13
3:43
this is it now click save to generate
3:46
the project
3:52
i hope you remember things from previous
3:55
video because i am going to skip some
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explanation here
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let's write the program now this is
4:02
where the transmit header data will be
4:04
stored
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rx header will store the header from the
4:11
incoming message
4:13
let's create the arrays to store the tx
4:16
data
4:16
and the rx data
4:21
and at last the variable for the tx
4:26
mailbox
4:29
now in the main function start the cam
4:37
activate the notification for the data
4:39
pending in the rx fifo
4:42
everything i am doing has already been
4:44
covered in the previous video
4:46
kindly watch it if you don't understand
4:48
something here
5:11
after activating the notification we
5:13
will load data in the tx header
5:20
i am going to send 2 data bytes so dlc
5:24
is 2.
5:29
we will be using standard id and the id
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will be 0 cross
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446 this is the id of f446re
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whenever this controller will send the
5:42
message this id
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will act as the id of the sender now
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before i send data
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let me explain what i actually want to
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achieve here
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this controller will send the two data
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bytes
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the first data byte will act as delay
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for the led on the second
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board and the second data byte will act
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as the number of times
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that led will blink when the second
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controller receives this message
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the led on it will blink according to
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these instructions
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i am not going to send the data here but
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instead let's send it in the xd callback
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function
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when the user button is pressed this
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function will be called
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and we will send the data here
6:30
the delay will be 100 milliseconds
6:34
and the loop will be repeated 10 times
6:43
now we will send the data using hull can
6:45
add tx message
6:54
here we have activated the notification
6:57
for the receive
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when this controller will receive
7:00
message from the blue pill
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a message pending callback will be
7:14
called
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inside this callback we will receive the
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data from the fifo
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zero the header will be stored in rx
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header
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and the data will be stored in the rx
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data
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let's create a flag
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we will just do one more check if the
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data length is two bytes
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then the flag will set
7:53
if the flag is set we will blink the led
8:10
the number of times it will blink will
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be the second byte of the rx data
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and the time delay will be the first
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byte
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and finally reset the flag so that there
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is no false blink
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let's build it once
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i think i forgot to enable the interrupt
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for the xd line
8:44
let's enable it
9:01
next we have to configure the filters
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we will configure inside the can
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initialization function
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here is the filter configuration that i
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am
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using enable the can filter
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i am assigning 20 filter banks to the
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can one
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out of these 20 i am using filter bank
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number 18.
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this is the id that should pass through
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this id will be assigned to the blue
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pill later
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and the same value in the mask id
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register also
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i am using fifo 0 to store the incoming
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message
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this configuration is explained in the
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previous video
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so make sure you watch it let's build it
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now
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now since i am going to connect both the
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controllers to the same computer
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i don't want the sd links to mix up so i
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am going to assign the respective sd
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links to their controllers
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right now i have connected only the f446
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and if i scan the sd link here it will
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only show one
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so we will keep this sd link assigned to
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this board
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that's all for this now let's create
10:33
another project for blue pill
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i am doing the basic setup and running
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the system at maximum clock
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activate the can peripheral we have to
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select the same board rate here
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that is 500 000 bits per second
11:01
here i will use the fifo 1 for receiving
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the message
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this is just to demonstrate pc 13 is the
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led on board
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so select it as output that's it
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click save to generate the project
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i am going to use same code that i used
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in 446
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so copy everything from here
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we are not using the external interrupt
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in blue pill
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let's copy this part now
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here we don't have can one or can two
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instead it's just
12:01
can as i said i am using
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fifo one here so replace all fifo zero
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with fifo one
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the transmit id for blue pill will be
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zero cross one
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zero three
12:26
now let's copy the while loop
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here the led is pc13
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now since we are not using the external
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interrupt here
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we will send the data in this loop
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itself
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let's define the data that we will send
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and after the led is finished blinking
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we will send the data using
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hollard tx message
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now copy the filter configuration
13:32
here the start slave bank does not
13:34
matter
13:35
like i explained in the previous video
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and the filter bank should be between 0
13:53
to 13.
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the id that will be allowed to pass is 0
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cross 4 446
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the id of the f4 controller
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ok this should be can and we are using
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fifo one
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all right it's correct now so i have
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removed the f4 sd link
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and now only the blue pill is connected
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if we scan the sd link only one shows up
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and we will assign it to the blue pill
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now the code has been loaded into both
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the microcontrollers
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let's see if it works as expected
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i have also connected the analyzer to
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see the data flow
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channel 0 is connected to the tx of 446
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and channel 1 is connected to the tx of
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blue pill
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pay attention to the leds on both the
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microcontrollers
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the communication will start only when
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the button on the 446 is pressed
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as you can see when i press the button
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the led on blue pill blinks for some
15:28
time
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and then the led on 446 starts blinking
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and then everything stops until the
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button is pressed again
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this is exactly what we programmed it to
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do
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let's see the data this is the message
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sent by
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four four six you can see the id
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the control field the two data bytes
16:00
once this message is received by the
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blue pill the led will blink
16:04
and once the led finished blinking the
16:06
blue pill will send the message
16:09
and here you can see the message sent by
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blue pill
16:24
you can see the same process will repeat
16:26
every time we press the button
16:33
let's try changing the data for both of
16:48
them
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you can see the led is blinking somewhat
17:23
longer now
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also observe the message on the analyzer
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there is almost a delay of four seconds
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here
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we are sending the 100 milliseconds
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delay and 40 times blink to the blue
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pill
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and that's why this 4 seconds so this
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works pretty good
18:06
now if you don't want to press the
18:08
button every time you can just send this
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data
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after the blinking is finished just like
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we are doing in the blue pill
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this way the process will keep going
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forever without any manual intervention
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let's run it now
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i will start the process by pressing the
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button once
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you can see the led on blue pill is
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blinking
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and now the led on the 446
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and this process is keep repeating by
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itself
18:59
this is how we can use the can for the
19:01
communication
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we can send up to 8 data bytes at a time
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filters allow the message filtering at
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the hardware level itself
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so the cpu don't have to do that work
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this is it for this video i hope you
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guys understood the can protocol
19:23
and how to use it for communication
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filter configuration is covered in the
19:28
previous video
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so watch it if you haven't watched it
19:31
yet
19:32
you can download the code from the link
19:34
in the description
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keep watching and have a nice day ahead
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