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How to use I2C in ESP32 || Interface LCD 1602 || Espressif IDE
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Jul 14, 2022
WATCH THE UPDATED VIDEO :::: https://youtu.be/xCVAuSobOxU
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0:01
[Music]
0:09
hello and welcome to controllers tech
0:13
this is another video in the esb 32
0:16
series and today we will see another
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peripheral the i2c
0:20
i2c or i squared c or iic stands for
0:25
inter-integrated circuit and it is a bus
0:28
interface connection protocol
0:29
incorporated into devices for serial
0:32
communication
0:34
we have covered a lot of videos in stm
0:36
32 series where we used i-2-c to
0:39
communicate with the sensor or to drive
0:41
some display
0:43
in order to show how the i2c works i am
0:46
going to interface a very famous lcd
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1602 display with the esp32 today
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if you have already seen my stm32 video
0:56
on this display this one is going to be
0:58
easier for you since we will be using
1:01
the same library that we have used in
1:03
sdm 32
1:05
otherwise if you are only watching the
1:07
esp32 series don't worry i will release
1:11
another video where i will explain how
1:13
the library was written
1:16
i couldn't cover everything in this
1:17
video that is why we will go with two
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videos
1:22
so today we will see how to port the i2c
1:24
lcd library from the stm32 to the esp32
1:30
if you are only interested in esp32
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just focus on the parts where we make
1:36
use of the library like how to import it
1:38
to the project or how to use the
1:40
functions to display data on the lcd
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and in the next video i will explain the
1:46
library
1:48
so this is the library we will be using
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today
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it basically uses the i2 c to interface
1:55
the lcd with the mcu
1:58
this is the stm32 related function which
2:02
writes the data using the i2c we will
2:04
change it obviously as per the esp 32.
2:08
the lcd is connected using the
2:10
p-c-f-8574
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which is basically an i-2-c expander
2:16
here are the data and clock pins for the
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i-2-c connection
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if we check our e-s-b-32 it has
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g-p-i-o-22 for the i-2-c clock and 21
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for the data
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we will be using these pins to connect
2:32
to the p-c-f
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you can see the p-c-f is attached to the
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l-c-d
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the 2 pins from the p-c-f are connected
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to the e-s-p-32
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they are the data pin which is the green
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wire connected between the s-d-a of the
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p-c-f and the d-21 of the e-s-b-32
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and the yellow wire is connected between
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the clock pin of the p-c-f and the d-22
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of the e-s-b-32
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we need to give 5 volts to the p-c-f for
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which i will use an external supply
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since esp32 doesn't have a 5 volts
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output
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all right now we have established the
3:12
connection so let's create a new project
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in esp-idf
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we will use an example template so go to
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peripheral i2c and let's use this i2c
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simple template
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let's rename this to i2 clcd
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so the project is generated successfully
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and here we have our main file
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before we proceed let's build it once
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make sure you select the correct mcu
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from here
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all right the build is successful
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without any errors and if the main file
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still shows error just click at some
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empty place and press enter
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since this is an example template it has
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some functions configured for the
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mpu6050
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let's delete them all
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all right here we have the function to
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initialize the i2c in master mode
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we will edit this function a little
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here we have to provide which i2 c we
4:38
are using
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since the board i am using has only one
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i2c so this must be the i2 c0
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next we have to input the data and clock
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pins
4:49
here you can see the data is pin 21 and
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clock is pin 22
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next parameter sets the pull-up feature
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for these pins
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since we are not using any external
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pull-up resistors let's keep the
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internal pull-up enabled
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the last parameter is the clock speed
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100 kilohertz is enough for the lcd to
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work you can also set high speed mode
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with 400 kilohertz
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this basically depends on the device
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specifications
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all right let's delete these defines
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from here
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in the master initialization function
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after defining the parameters it
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configures them using the function
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configure parameters
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and finally it will install the i2c
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driver
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this function takes the parameter as the
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i2c number which in our case is 0 the
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i2c mode which is master the length of
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the rx and tx buffers which is not
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needed since we are using the master
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mode and the buffers are only required
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in the slave mode
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the last is the interrupt flag which
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also we are not using today
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so the buffer lengths should be set to
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zero
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this will install the i-2-c driver and
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we are good to go with our l-c-d
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let's delete the m-p-u related functions
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in the main
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so inside the main function we are
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initializing the i2c and once it has
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been initialized we will log the success
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message
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now let's include the library files
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you can just drag and drop them in the
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main folder
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open the
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i2clcd.c file so that we can modify it
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remove the i2c handler definition
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the slave address for the p-c-f is zero
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cross four e
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the data will be written to the l-c-d in
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the similar manner but we just need to
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change the function to write data using
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e-s-b-32
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this part will remain similar across
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whatever controller you use
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now let's see what functions are
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available in the esb 32 i2c library
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i2 c master right to device the
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parameters are the i2c number the device
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address the buffer we want to write the
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buffer length and the timeout for the
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function
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this function should work for us
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also note here that the device address
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is being shifted to left by 1 position
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this info will be needed later
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all right let's use this function to
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send the data to the lcd
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i am defining the error variable
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the first parameter is the i2c number
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which is zero in our case
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then we have the slave address which is
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defined here
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next is the buffer we want to send that
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will be the data t itself
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the buffer size is 4 bytes
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and let's keep the time out to be 1
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second
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this function will return zero on
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success and i guess minus 1 if it fails
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anyway if the error is not zero we will
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log this on the console
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for this we must define the tag first as
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it's defined in the main file
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and now we will log using this tag that
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there is some problem in sending the
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command
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the same functions will be used to send
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the data also
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so that's all we need to modify in this
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library
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in the lcd header file remove the stm32
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inclusion
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let's build it once
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we have errors regarding the use of i2c
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number
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this is because we haven't included the
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i2c driver yet so let's include this in
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the lcd library
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one last and very important thing
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in order to include a library in the
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project we must register it in the c
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make list file
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in this idf component register we will
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register a new source file i2 clcd dot c
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all right let's build it again
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since we have registered a new source
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it's going to build the entire project
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again
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and you can see the errors regarding the
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inclusions are gone now
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i forgot to change this delay function
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whole delay is used to provide delay in
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milliseconds so we need to use an
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equivalent function here in esp32
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you sleep is used to put the mcu in
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sleep but this takes the argument in
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microseconds
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so change all the delays to u sleep and
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modify the parameters
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we also need to include the header file
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for this u sleep function
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so everything is fine now and our
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library is ready to be used with the
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esp32
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if you are only using esp32 you can just
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take this library include it in the
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project and modify the c make list file
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as i said i will explain the library in
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the next video
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now we will use this library to print
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something on the lcd
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in the main file include the lcd header
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file
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now in the main function first we need
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to initialize the lcd
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remember the i2c must be initialized
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before we initialize the lcd
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lcd put cursor will put the cursor in
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the zeroth row and zeroth column which
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is in the beginning of the top row
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we will send the string hello world to
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this position
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then we will put the cursor at the first
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row and zeroth column that is in the
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beginning of the bottom row
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and we will print another string there
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that's it let's build the code now
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there are no errors so we will run it
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using the run configuration in the idf
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application tab
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we will also check the logs to see if
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there is any error
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make sure the serial port is correct
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here
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the log is showing errors in sending
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commands and data to the lcd
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remember we defined them in the i2c lcd
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source file
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all right the error is because of this
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address
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this address is 8 bits long which
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include the read or write bit also
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since the address here is shifted left
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by one place means the esp32 functions
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also take the 7-bit address just like
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arduino
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so we will shift this address to the
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right by one place making it a 7-bit
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address
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all right let's build and run the code
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again
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you can see in the console there are no
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errors this time
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the lcd is displaying our strings hello
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world in the top row and from esp32 in
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the bottom row
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so things have been working pretty good
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so far
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remember that the lcd can only print
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ascii characters so if you want to
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display numbers you need to change them
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to respective ascii characters first
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for example if i want to print any
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number first of all i need to define a
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buffer where i can store the converted
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ascii characters
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we will use s printf to change the
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number to the characters
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then simply put the cursor where you
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want to print the number and send the
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buffer to the display
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you can see the number is being
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displayed on the lcd
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similarly say if we are displaying the
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float value we need to change the
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formatting in the s print f and the rest
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will remain the same
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the l c d is displaying the float number
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as well
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basically it can display anything in the
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ascii format
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i hope you understood how to use the
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library to display the data on the lcd
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if you are only watching this channel
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for the esp32
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and want to understand how the library
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was written check out the very next
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video
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this is it for this video
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you can download the code from the link
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in the description
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keep watching and have a nice day ahead
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[Music]
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you