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LVGL on STM32 - PART 4 || Send and Retrieve data from Display
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Nov 4, 2023
Purchase the Products shown in this video from :: https://controllerstech.store ________________________________________________________________________________________ LVGL PART 3 :::: https://youtu.be/SnrHpcujpyU LVGL PART5 :::: https://youtu.be/0--7qFmWZMQ LVGL STM32 Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8ghGES4CUTjHTn_G4gly_atz STM32 Playlist :::: https://www.youtube.com/playlist?list=PLfIJKC1ud8gga7xeUUJ-bRUbeChfTOOBd DOWNLOAD THIS PROJECT FROM :::: https://controllerstech.com/lvgl-on-stm32-part-4/ ________________________________________________________________________________________ ******* SUPPORT US BY DONATING****** https://paypal.me/controllertech *******Join the Membership******* https://www.youtube.com/channel/UCkdqtSMnhYuMsJkyHOxiPZQ/join
View Video Transcript
0:01
[Music]
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hello and welcome to controllers Tech
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this is the fourth video in the lvgl
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series and today we will see how to send
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and retrieve data from the display I am
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going to use the U to send the data from
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the computer to the MCU which will then
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display on the UI I will also use the
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ADC to read the potentiometer and modify
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the arc on the display according to it
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to send the information from display to
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the MCU we will use three buttons on the
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display which will be used to control
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the LEDs on the MCU let's continue with
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the previous project on the
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lvgl here I have imported the project to
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the IDE we need to include art ADC and
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LEDs to our project so let's open the
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cube MX the nucleo and Discovery boards
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support the virtual comp port for the
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uart so I am going to use the same here
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is the schematics of the nucleo L
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496 you can see the pins pg7 and pg8 are
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connected to the SD link RX and TX pins
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these pins are actually connected to the
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U peripheral of the SD link and hence we
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can use the SD link USB as the virtual
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comp Port you can also use an external
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USB to TTL module to communicate to the
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computer using the uart let's enable the
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low power uart in the asynchronous mode
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the default pins assigned are the pins
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PC 0 and
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pc1 let's configure the pin pg7 and pg8
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as the RX and TX pins for the uart now
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we need to configure the
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parameters I am setting the board rate
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to
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115200 the word length should be 8 Bits
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let's also enable the global interrupt
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for the uart now we will configure the
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ADC let's enable the adc1 channel one in
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the single-ended mode the pin pc0 has
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been selected as the channel one pin the
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resolution is set to 12 bits I am
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leaving everything to default as I will
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use the blocking mode to read the ADC
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value now let's set the LEDs as output
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here you can see in the schematics we
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have the red LED connected to the pin
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pb14 we have a blue LED connected to the
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pin
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pb7 we have one more green LED connected
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to the pin
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pc7 let's set these three pins as output
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in the cube MX I am also renaming the
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pins so that it will be easier for us to
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select them in the
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code
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that is all we need to do here click
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save to generate the project I have
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already created a project in square line
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Studio I will explain it there is a text
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area where we will display the data
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received from the uart I am also using
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an arc to display the ADC value here the
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range for Arc is set between 0 to 100 so
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we will also map our ADC value within
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this range then we have three switches
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which will be used to control the three
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LEDs on the board I have also created
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events for these switches which will
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trigger when the switches are clicked
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here we will call these functions which
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we will Define later in the
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code let's export the UI files let me
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delete the previous UI folder from the
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project and we will copy our newly
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generated UI folder inside
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it here in the UIC screen source file
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you can see all the components we added
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to the UI all right let's start by
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writing the event file include the main
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header file once the first switch is
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clicked the LED one clicked function
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will be called here we will first check
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the current state of the switch you can
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see all the available States but we are
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interested in the checked State this
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means that the switch has been enabled
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if this happens we will turn the LED 1
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on otherwise if the state is not checked
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which means that the switch is disabled
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turn the LED off repeat the same for the
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other
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functions that is all we need to do in
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the event file let's go to the main file
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now here after the UI has been
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initialized I ized we will receive the
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data from the uart in the interrupt mode
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I am setting the 32 bytes limit here as
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this is enough to test the UI let's
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define the RX data array where the
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received data will be stored once all
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the 32 bytes have been received or there
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is an idle line before that the uart
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interrupt will trigger and the RX event
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call back will be
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called here we will set the received
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data to the text area
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now clear the RX buffer so that there is
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no residue from the previous
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reception call the receive to idle
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function again as Hall disables the
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interrupt after each
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call now we will write one more function
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for the ADC read and write to the
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UI let's also Define the map function to
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map the ADC values within a certain
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range inside the ADC read function we
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will first start the ADC
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then PLL for conversion to
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complete then read the ADC value and
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stop the
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ADC Now map the ADC value which can
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range from 0 to
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4,095 to the range 0 to
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100 and finally we will set the value to
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the arc defined in the
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UI let's call this ADC function in the
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while
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loop that is all let's build the code
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now we don't have any errors so let's
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flash it to the
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board let's see the connection before we
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proceed with the output I have already
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shown the LCD Connection in the previous
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videos so let's skip that here is how
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the potentiometer is connected to the
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board it is powered with 3.3 volts from
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the board and the ADC pin is connected
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to the pin
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pc0 I am using the virtual come for the
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uart so there is no need to connect any
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external hardware for the same but if
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you do want to use a TTL module the
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connection should be as shown here the
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RX pin from the board connects to the TX
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pin of the module and the vice versa all
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right let's see the working now here you
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can see the UI has been loaded to the
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display we will first test the buttons
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and ADC and later the uart you can see
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the LEDs on board are responding to the
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switches each LED is separately
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controlled by a switch the ADC is also
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responding well the arc denotes the
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position of the potentiometer and is
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ranging from Zer to
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100 let's see the U
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now I am using this wch serial Port
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application on my Mac let's open the
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comp port at 115200 board and eight data
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bits with no
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parity send the string hello world you
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can see it is displayed on the text area
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defined for
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it everything is working fine I have
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defined the array of 32 bytes in the
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code so it can receive up to that limit
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pretty well so we were able to send the
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data to the display receive the input
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from it and also display the a C value
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on it I hope you understood the
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procedure well in the next video I will
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cover the keyboard and how we can
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receive and store the data entered on
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the display this is it for today you can
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download the code from the link in the
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description leave comments in case of
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any doubt keep watching and have a nice
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day ahead