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Interface TM1637 (7-Seg Display) with STM32 || PART 2 || Display Clock
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Jun 25, 2024
Purchase the Products shown in this video from :: https://controllerstech.store ________________________________________________________________________________________ TM1637 PART1 :::: https://youtu.be/kNZQb1TjgF4 STM32 Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8gga7xeUUJ-bRUbeChfTOOBd DOWNLOAD THIS PROJECT FROM :::: https://controllerstech.com/display-clock-on-tm1637/ ________________________________________________________________________________________ ******* SUPPORT US BY DONATING****** https://paypal.me/controllertech *******Join the Membership******* https://www.youtube.com/channel/UCkdqtSMnhYuMsJkyHOxiPZQ/join Join the Discord Server https://discord.gg/D32JE5wKyD Join the Telegram Group https://t.me/controllerstechdiscuss
View Video Transcript
0:01
[Music]
0:09
hello and welcome to controllers Tech
0:12
this video is the part two of the series
0:14
covering how to interface the S segment
0:17
tm1637 display with SDM
0:20
32 in the previous video we saw how to
0:23
connect the display to the MCU how to
0:26
configure the cube MX and how to make
0:28
the display work by writing some basic
0:31
functions we will continue the same
0:34
project created in the previous video
0:36
but today we will add more functions to
0:38
the
0:39
library we will also use the SDM 32
0:42
inbuilt RTC and display the time on this
0:46
device here I am using the same project
0:49
that we created in the previous
0:52
video we already have a function to
0:54
display numbers on the device but this
0:57
function takes the segment data as the
0:59
parameter
1:01
today we will write another function
1:03
where we can pass the numbers to the
1:04
parameters instead of passing this
1:06
segment data let's define an array which
1:10
contains the segment data for the
1:12
equivalent number I have already
1:15
explained how this data is created in
1:17
the previous
1:19
video here I just have the data for the
1:22
numbers as that is only required for the
1:24
clock but you can also add more
1:26
characters to this array all you need to
1:29
do is write a one to the segment which
1:31
you want to turn on and you can pretty
1:34
much have any character you want all
1:37
right let's write a new function to
1:38
display the number on the
1:40
device the parameters will be the
1:43
address where you want to display the
1:45
number the number itself and the
1:48
colon this parameter colon will
1:50
basically decide whether you want to
1:52
display the colon or not let's define a
1:56
buffer to store four bytes of data here
2:00
number in the parameter can range
2:01
anywhere between one digit to four
2:04
digits so we need to First determine the
2:07
number of digits this parameter has if
2:11
we divide the number by 1,000 and we do
2:13
get a quotient that means the number has
2:16
four digits in
2:17
total otherwise if we get a quotient on
2:20
dividing it by 100 that means it has
2:23
three
2:24
digits the similar checks will be
2:26
performed to determine the number of
2:28
digits in the parameter
2:30
number now we will extract the segment
2:33
data for the equivalent number and store
2:35
it in the buffer
2:36
array note that here I am using the
2:39
modulo operator to extract the digit at
2:42
the unit place of the num
2:44
parameter basically if the number is
2:48
1,234 this operation will extract four
2:51
from it and then the data stored in the
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segment map for this number will be
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stored in the zeroth element of the
2:57
buffer array then update the a num
3:00
variable by dividing it by
3:02
10 this will eliminate the unit place
3:05
from the number so if we divide
3:09
1,234 by 10 the output will be
3:12
123 eliminating four from it this Loop
3:16
repeats as many times as there are a
3:18
number of digits in the num
3:21
variable now we have the segment data
3:23
stored in the buffer array so we will
3:26
send it to the
3:27
display but before that we all also need
3:30
to take care of the colon if the colon
3:33
value is set to one we will enable the
3:35
colon by writing a one to the most
3:37
significant bit of the second digit that
3:40
is the value stored in the first element
3:42
of the buffer
3:43
array finally call the function WR data
3:46
to send the data to the given
3:49
address let's define this function in
3:51
the
3:52
tm1637 header file so that we can call
3:55
it in the main file all right let me
3:58
comment out the previous
4:00
code Now call the function right number
4:03
I am setting the address of the first
4:05
digit let's write the number
4:08
5,678 and I want to display the colon
4:12
also all right let's build and Flash the
4:15
project to the
4:17
board you can see the device is
4:20
displaying the number but it's not quite
4:22
what we
4:23
wanted the number is in the
4:26
reverse well this is because as I
4:29
explained explained here we get the
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digit at the unit place so in this case
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we got the number eight this number
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eight will be stored in the zeroth
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element of the buffer
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array when the data is sent to the
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display the zeroth element is sent first
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and hence the number eight is being
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displayed on the address c0
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hex to resolve this issue we can start
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storing the data from the
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end for example we will store the number
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eight in the third element number seven
5:00
in the second element six in the first
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element and five in the zeroth
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element this length minus one is
5:08
important as the array positioning
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starts from zero all right let's flash
5:14
this modified project to the board you
5:17
can see now we have the number
5:20
5,678 on the
5:22
display let's say I do not want the
5:25
colon in the middle so set this colon
5:27
value to zero and Flash the codeing
5:30
again you can see the colon has
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disappeared we can display any number on
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the device be it a single digit or even
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a four-digit
5:40
number let's display the number
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95 you can see it being displayed on the
5:47
device note that the device retains the
5:50
data stored in other addresses as well
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so those values will still remain there
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one way you can handle it is by writing
5:58
zeros on remaining
6:00
digits you can also modify the function
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to send the data bite with value zero to
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turn off all the segments of a
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particular digit we can also display the
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number on a particular
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digit here I want to display the number
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seven on the last
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digit you can see the number seven is
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being displayed on the digit number four
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so we are able to display the numbers
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directly on the device without having to
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worry about the segment data for the
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same now we will display the clock on
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this
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device I am going to use the inbuilt RTC
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of the SDM 32 controller to save and
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fetch the clock data I have already
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covered a tutorial explaining how to
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make it work so I am not going to
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explain the RTC part in much detail here
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instead we will focus on fetching and
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displaying the clock data let's enable
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the lowspeed external Crystal first the
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blue pill has this
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32.768 khz Crystal on it and we will use
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it to provide the clock for the
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RTC now go to the RTC and activate the
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clock Source also activate the calendar
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otherwise we won't be able to set the
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time now go to clock configuration and
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change the clock source to
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LS if your controller board does not
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have a dedicated Crystal for this you
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can still use the internal oscillator of
7:29
40
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khz let's configure the parameters Now
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set the data format to Binary so that we
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can directly deal in decimal values you
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can leave this empty or set the current
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time we are not interested in the
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calendar here so leave it as it is that
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is all the configuration we need click
7:51
save to generate the project we will
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first write a separate function to set
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the RTC time so scroll down to the RTC
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initialization function and copy this
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part where the time is being set also
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comment it out as we do not want the
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time to set every time the board
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resets let's define a function to set
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the time the parameters of this function
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will be hours minutes and seconds also
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copy the RTC time structure from the
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initialization function instead of this
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default time we will pass the parameters
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here now we need to create one more
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function to fetch the current time from
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the
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RTC the parameters of this function will
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be pointed to the array where the
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current time will be stored Define a RTC
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time structure where the current time
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will be stored Now call the function RTC
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get time to fetch the current time and
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store it in the structure we just
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defined the data will be stored in the
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binary format now we need to copy the
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time data from the structure to our
9:00
array all three elements of the time
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data have values in two-digit format so
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we will store the unit Place digit first
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and the 10 Place digit repeat the same
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process for minutes and hours now we
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have separated the time into six
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different digits which is stored in an
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array of six bytes there is one
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important thing I forgot while setting
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the time after the time is set we will
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write a random value to the RTC backup
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register this register is used to make
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sure that the time does not reset when
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the MCU resets for some reason you can
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write any random value to this
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register in the main function after
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everything has been initialized we will
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set the time but before setting the time
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we need to make sure that the backup
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register does not has the same value
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which we stored into it if the backup
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register has the same value that means
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the time was already set and we will not
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set it again the RTC backup register
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does not lose its data when the board is
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reset therefore it is used as a shield
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to protect the execution of the same
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statement again and again let's define
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an array to store the six bytes of the
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current
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time inside the while loop we will call
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the function get time to fetch the
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current time from the RT TC and store
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this time in the array we
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defined now we need to send this data to
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the display and to do that we will write
10:38
a new function in the
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tm1637 source
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file the parameters of this function
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will be the pointer to the array which
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contain the times data and the colon
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variable let's define a buffer to store
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four data
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bytes now we need to store the segment
10:56
data with respect to the number we have
10:58
in the time array the segment data will
11:02
be stored in Reverse storing the seconds
11:04
in the last two digits and minutes or
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hours in the first two the time array
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contains the frequently changing data in
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the beginning of the array for example
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we have seconds first then minutes and
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hours in the end the time array already
11:21
contains the individual numbers so we
11:24
don't need to extract them as we did in
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the previous
11:27
function this much should be enough to
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display the time but we also need to
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deal with the colon part I want the
11:35
colon to Blink every second usually that
11:38
is how it is in most of the
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clocks let's define static variables D
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colon and S
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change the D colon variable will be used
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to change the colon state every second
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but we don't know how frequently this
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function will be
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called for example you can use this code
11:58
in free R toos and call this function
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every 100
12:04
milliseconds in order to make sure that
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a second has been passed we will compare
12:08
the value of the S change variable with
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the first element of the time
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array this element contains the unit
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digit of the
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second if the value here is different
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that means 1 second has been passed and
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we can change the state of the Decon
12:25
variable but again this change in the
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state of the decol depends on whether
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the colon variable is sector one or not
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now if the D colon is changed to true we
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will update the first element of the
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buffer by writing a one in the seventh
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bit otherwise leave the data as it is
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now update the S change variable with
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the latest value of the unit position in
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the time
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array also we don't want to send the
12:54
data continuously so we will call the
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send function here itself
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this will only send the data to the
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device if there is some change in the
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unit position in the time
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array I am calling it unit position
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because since we have only four digits
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in the display we can either display
13:12
minutes with seconds or hours with
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minutes in either case the unit position
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contains the data which changes most
13:21
often all right let's define this
13:23
function in the header file so that we
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can call in from the main file in inside
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the while loop after fetching the time
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pass the array to the right time
13:34
function note that the array current
13:36
time has six bytes data but the buffer
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array defined inside the Righttime
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function can only store four bytes so
13:44
the first four bytes which contains
13:47
seconds and minutes will be stored in
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the buffer array there is some error
13:52
here and this is because we need to pass
13:54
the address of the RTC time
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structure let's give a delay of 200
14:00
milliseconds in the while
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loop also set the current time in the
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set time
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function let's build and Flash the code
14:11
to the board you can see the minutes and
14:14
seconds are being displayed on the
14:16
device note the colon in the middle it
14:19
is blinking every second just as we
14:21
wanted it to I am fast forwarding the
14:25
video so that you can see the change in
14:27
the minutes at this point even if we
14:30
reset the board the time will not start
14:33
from the beginning it will continue to
14:35
run let me show this in the debugger you
14:39
can see even when the board is reset the
14:41
time does not reset it continues where
14:44
it was stopped it happened because we
14:47
have added a layer of protection on the
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set time function now let's say I want
14:52
to display the hours and minutes instead
14:55
of minutes and seconds the minutes data
14:58
starts from the second element of the
15:00
time array so here instead of passing
15:04
the array from the beginning we will
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pass it from the second
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element here I do not want to Blink the
15:11
colon every minute so comment out this
15:14
line if you want to display the colon
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change it to one or leave it zero
15:20
otherwise I want to display the colon so
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I am setting it to one let's build and
15:26
un Flash the code again you can see the
15:29
current hours and minutes are being
15:31
displayed on the device so I hope you
15:34
understood how to display the clock on
15:36
the tm1
15:38
1637 since the device has only four
15:40
digits we can either display the minutes
15:43
and seconds or hours and minutes the
15:46
latter seems more logical of course as I
15:49
mentioned earlier you can also modify
15:52
this segment data and add more
15:54
characters to the
15:55
display this is it for the video
15:59
you can download the code from the link
16:01
in the
16:02
description leave comments in case of
16:05
any doubt keep watching and have a nice
16:08
day ahead
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