prepare png file for arduino tft display for sale

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For the features, maybe I"m missing it but I don"t see the benefit? Why would I load a large image just to show a small portion? That would take longer then loading only the small portion I need to see.

I plan to have about 15-20 different screens, for changing settings, etc... Each screen will have its own icons and they will usually be in different locations on the screen.

Can some one refer me to the available tutorial or suggest what to do for dc pin mentioned in the below tutorial.I have not connected it because i dont want to break my tft

Once the display is wired correctly (with level converters if needed) then it is a case of finding the right library for the driver chip that is fitted inside the TFT screen.

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I got a 7-inch TFT LCD display (800x480 pixels, capacitive touch screen) to use with an Arduino DUE processor. It"s a ER-TFTM070-4V2.1 display, came with a shield for a DUE or Mega2560 processor, uses an SSD1963 processor. Got it working so it ran the examples in the UTFT library, displaying sine waves, moire patterns etc. Found some files of UTFT fonts and started putting together an interface of a medical ventilator, now it displays major parameters using three different fonts simultaneously, looks cool so far.

The Arduino DUE runs on 3.3V, of course, and has a voltage regulator on board so I can feed it 9VDC. It runs well with that and the display looks as good as I can make it (which isn"t saying much, my artistic talents are mediocre at best).

I"d like to have it display a small picture (150x100 pixels) in one part of the display. Picture is available in any of several formats (BMP, GIF, PNG, JPG etc.).

Voltage type: 5v or 3v voltage input voltage，input is selectable. Because TFT can only work under 3.3 V voltage, so when the input voltage VIN is 5V, need through the 3.3 V voltage regulator IC step down to 3.3V , when the input voltage of 3.3 V, you need to use the zero resistance make J2 short , is equivalent to not through the voltage regulator IC for module and power supply directly.

SainSmart 2.8" TFT LCD Display is a LCD touch screen module. It has 40pins interface and SD card and Flash reader design. It is a powerful and mutilfunctional module for your project.The Screen include a controller ILI9325, it"s a support 8/16bit data interface , easy to drive by many MCU like arduino families，STM32 ,AVR and 8051. It is designed with a touch controller in it . The touch IC is XPT2046 , and touch interface is included in the 40 pins breakout. It is the version of product only with touch screen and touch controller.

Voltage type: 5v or 3v voltage input voltage，input is selectable. Because TFT can only work under 3.3 V voltage, so when the input voltage VIN is 5V, need through the 3.3 V voltage regulator IC step down to 3.3V , when the input voltage of 3.3 V, you need to use the zero resistance make J2 short , is equivalent to not through the voltage regulator IC for module and power supply directly.

Whatever you are currently celebrating, Christmas, Hanukkah, Jul, Samhain, Festivus, or any other end-of-the-civil-year festivities, I wish you a good time! This December 25th edition of the Nextion Sunday Blog won"t be loaded with complex mathematical theory or hyper-efficient but difficult to understand code snippets. It"s about news and information. Please read below...After two theory-loaded blog posts about handling data array-like in strings (Strings, arrays, and the less known sp(lit)str(ing) function and Strings & arrays - continued) which you are highly recommended to read before continuing here, if you haven"t already, it"s big time to see how things work in practice! We"ll use a string variable as a lookup lookup table containing data of one single wave period and add this repeatedly to a waveform component until it"s full.A few weeks ago, I wrote this article about using a text variable as an array, either an array of strings or an array of numbers, using the covx conversion function in addition for the latter, to extract single elements with the help of the spstr function. It"s a convenient and almost a "one fits all" solution for most use cases and many of the demo projects or the sample code attached to the Nextion Sunday Blog articles made use of it, sometimes even without mentioning it explicitly since it"s almost self-explaining. Then, I got a message from a reader, writing: "... Why then didn"t you use it for the combined sine / cosine lookup table in the flicker free turbo gauge project?"105 editions of the Nextion Sunday blog in a little over two years - time to look back and forth at the same time. Was all the stuff I wrote about interesting for my readers? Is it possible at all to satisfy everybody - hobbyists, makers, and professionals - at the same time? Are people (re-)using the many many HMI demo projects and code snippets? Is anybody interested in the explanation of all the underlying basics like the algorithms for calculating square roots and trigonometric functions with Nextion"s purely integer based language? Are optimized code snippets which allow to save a few milliseconds here and there helpful to other developers?Looking through the different Nextion user groups on social networks, the Nextion user forum and a few not so official but Nextion related forums can be surprising. Sometimes, Nextion newbies ask questions or have issues although the required function is well (in a condensed manner for the experienced developer, I admit) documented on the Nextion Instruction Set page, accessible through the menu of this website. On top of that, there is for sure one of my more than 100 Sunday blog articles which deals not only with that function, but goes often even beyond the usual usage of it. Apparently, I should sometimes move away from always trying to push the limits and listen to the "back to the roots!" calls by my potential readers...Do you remember the (almost) full screen sized flicker free and ultra rapid gauge we designed in June? And this without using the built-in Gauge component? If not, it"s time to read this article first, to understand today"s improvements. The June 2022 version does its job perfectly, the needle movement is quick and smooth, and other components can be added close to the outer circle without flickering since there is no background which needs constantly to be redrawn. But there was a minor and only esthetic weak point: The needle was a 1px thin line, sometimes difficult to see. Thus, already a short time after publishing, some readers contacted me and asked if there were a way to make the needle thicker, at least 2 pixels.

Several ways exist to display bitmap images, pictures so to say, on a screen attached to an Arduino, ESP8266 or ESP32. In the present project we convert a color picture into a c-array that is either included in a sketch or saved in a file that is called from within a sketch. The screen used is a 1.3 inch, 240*240 pixel TFT display with ST7789 controller and SPI interface. Because the file size of a 240*240 color bitmap is way too large to fit program memory in an Arduino Uno we are using an ESP32 microcontroller board: ESP32-WROOM-32. The 1.3”, 240*240 TFT is one of my favorite displays, not only because of its 65,536 available colors (16 bits per pixel, RGB565) but also because of its fast SPI interface which is meticulously supported by Bodmer’s TFT_eSPI.h library.

Compared with current LCD displays and OLED displays, TFT type screens offer the luxury of nearly unlimited color. While it is possible on OLED displays to show pictures, the constraint with this type of display is that pictures are always presented in monochrome. A TFT display shows images as crisp and colorful as your smartphone’s screen does. Of course your smartphone has more pixels than the humble 240*240, which necessitates some cropping and scaling. In this project I started with a big, 2521*1688 pixels jpg image downloaded from Wikipedia.

To possess a TFT screen is one thing, making it work, that is: showing color pictures, needs some investment in ideas, time and effort. As graphical functions are called via a supporting library the selection of a competent library is of prime importance. Another issue is the communication protocol between microcontroller and display. Among the available libraries the TFT_eSPI.h library offers superior support for a variety of controllers / microcontroller board / TFT display configurations, including the configuration used in the current project.

TFT_eSPI can be installed via the Library Manager in the Arduino IDE (Tools → Manage Libraries). Additional Configuration: see section Software. Install the most recent version.

Figure 1 shows the wiring diagram. Wiring is straightforward: the VCC pin of the display breakout board is connected to the 3.3V pin of the ESP32. GND is connected to GND. Of the remaining display pins only four are necessary. Pins marked ‘SCL’ and ‘SDA’ (on other SPI displays sometimes labeled as SCLK and MOSI) are connected to pins D18 and D23 of the ESP32. Pin ‘RES’ on the TFT display is connected to pin D4 of the ESP32, and pin ‘DC’ of the display goes to pin D2 of the ESP32. Pin ‘BLK’ of the TFT is not connected.

The example here, shown in figure 1, is a picture of a ladybug. The image was acquired via a search on Wikipedia. Its credentials are: Gilles San Martin from Namur, Belgium – Coccinella magnifica, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=7694675. The original picture is beautiful, but it is also huge compared with my humble TFT: 2521*1688, format: jpg.

Resulting after all the photo editing was a 173 kB BMP image file (‘ladybug.bmp’) with dimensions 240*240 and in True Color = R5G6B5, 16-bit color depth (64k colors).

Once the proper size, color depth and format had been obtained the moment had arrived to convert the picture into c-array format. This is the format recognized and processed by the Arduino compiler.

A very convenient program to convert BMP image files to c-array format is ‘lcd-image-converter’. This is a Windows program, freely available on the internet. What one needs to do in lcd-image-converter is shown in figures 2 and 3.

First thing to do is to start the program, provide a name for the project (‘ladybug’) and check the conversion parameters. This is done via Options, Conversion. Be sure that Block Size is 16 bit, byte order ‘Little Endian’ (figure 2).

Via ‘File’ and ‘Convert’ the end result is produced: a file named ‘ladybug.c’ (file size here: 638 kb). This file is in ascii format. Its contents can be inspected with an ascii editor (Notepad, Notepad++, Gedit).

There are two ways to work with a c-array in a sketch: the ‘internal’ option, that is that the c-array is copy-pasted into the sketch, and the ‘external’ option, that includes a call from the sketch to a file located in the same folder as the sketch. Both options have pros and cons. Here we will provide both options.

0x4b41, 0x4321, 0x4321, 0x4301, 0x42e1, 0x4301, 0x4301, 0x4b41… ……..and so forth until the final pixels……. 0x8ccd, 0x84ad, 0x848c, 0x848c, 0x846c, 0xa571, 0xa571, 0xa571

The essential image c-array data can be placed into a separate file while all data are ‘imported’ at compilation time via a simple ‘include’ instruction inside the sketch. This has the advantage of a clean sketch that is easy to edit. The data file needs to be saved in the same folder as the sketch.

0x4b41, 0x4321, 0x4321, 0x4301, 0x42e1, 0x4301, 0x4301, 0x4b41… ……..and so forth until the final pixels……. 0x8ccd, 0x84ad, 0x848c, 0x848c, 0x846c, 0xa571, 0xa571, 0xa571

which is identical to the content of the 16-bit instruction in the ‘inclusive’ sketch. The 57,600 pixels remain neatly packed in a separate file. A sketch is supplied at the end of this article.

This library is extremely versatile, with many graphical functions, while it supports a great number of combinations of microcontroller boards and display controllers. The great difference between TFT_eSPI.h and alternative libraries, e.g. Adafruit_GFX.h and U8glib.h is that the so-called ‘constructor’ is absent.

The idea in TFT_eSPI is that all necessary parameters presented to the library are in a series of instructions bundled in a User_Setup.h file. As its name implies such a file is configurable by the end user. User_Setup.h contains calls to an array of drivers. Look around in the library’s folder named ‘User_Setups’. This folder is a playground for folks who like to experiment with all sorts of microcontrollers and displays. A superb idea!

– open User_Setup_Select.h and uncomment the line calling one of the pre-configured configuration files. In the present microcontroller-graphical controller combination this is a modified Setup24_ST7789.h.

After experimenting first with breadboards and jumper wires I decided to take a 7×9 cm soldering prototyping board and some pin sockets to solder a small robust bench that accommodates the ESP32-WROOM and the 2402*40 TFT (figure 4). Further software testing was done with this bench. Results were excellent. The TFT_eSPI library supports the ESP32 / ST7789 240*240 SPI TFT without any problem and, very important: very fast. I made and tested a variety of c-array coded images in a range of formats (e.g., 80*160; 128*128 and so on). They were all displayed very well on the small square screen. Condition is that the data file name is 8-character limited. One of these extra images, a picture of a dog called ‘bastien’, was cropped at 240*380 pixels and converted into a c-array (file size of the c-array: 1 MB). The sketch calling this c-array was perfectly compiled. Only the left part of the image was shown on screen with the instruction ‘tft.pushImage (0,0,240,240, bastien);‘, and the same happened when the instruction was changed into ‘ tft.pushImage (0,0,240,380,bastien);‘. This means that the TFT_eSPI library handles images benevolently. The instruction ‘’tft.pushImage (0,0,120,120, bastien);‘ produced an image on the left lower quadrant of the display, and this image contained the left lower quadrant of the bitmap picture.

An interesting option is to place several external c-array.h files into progmem in order to produce a slideshow. I tried this with two 240*240 pixel images of the famous portrait of Che Guevara; one named ‘che-red.h’ and the other ‘che-grey.h’. With a simple delay () instruction a display time between successive images can be set. A series of calls to several more external c-array image files is possible as well. Here the prospect of animation looms. The successful compilation of a 240*380 pixel c-array image tempts me to investigate how far the the envelope of the ESP32 microcontroller can be pushed with images of increasing size. Such a project can easily be entertained on my previously assembled benches that accommodate bigger SPI- or parallel displays (up to 3.95”. 320*480 pixel TFTs *, **). Another attractive project is to use a card reader to transfer images with lightning speed, pixel after pixel, from an image file on SD card to the TFT display.

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Many times to make any user interface or nicely display content, we use icons/images. In this Instructable, you will be displaying icons or logos or images on your TFT screen from Arduino with using ATmega (microcontroller used in Arduino) Flash memory. It does not require any SD Card to store bitmap images or USB connection to send image data. We will convert images from any image format like .bmp, .jpg, .jpeg, .png to its hexadecimal equivalent to be stored in flash memory of arduino mega (ATmega2560).

All microcontroller has Flash memory, where the codes are stored permanently. Arduino Mega has comparatively good amount of Flash memory, ie 256 KB of which 8 KB used by bootloader. We will be doing two things:Monochrome icons/images: The icons or images will be displayed with single color, but takes very less memory. Just 1bit for one pixel.

Colored icons/images: It depends on the TFT screen used, for eg. 1.8" SPI TFT with ST7735 driver has 16bit color. Images or icons will just look like your phone screen, but it takes lots of space. it takes 16bits (2bytes) for each pixel (16times more!!).

It requires a TFT screen compatible with arduino, few jumper cables (dupont wires), breadboard and is recommended to use 3.3V -5V level shifters (but it works without it also :P ). But we have used evive . It has all the things required to do this without any additional wiring!! Hence it helps in avoiding the repetitive task for bread-boarding. evive uses the most commonly used 1.8" SPI based TFT (ST7735R driver) having 160px by 128px along with Arduino Mega 2560 R3. Also has internal logic level shifters for ideal usage.

https://sourceforge.net/projects/lcd-image-convert...This tool has all the options for large varieties of screens available. You can even draw your own icon!!.

Also we may need to use some image resizing tool as most of the images available on internet are of very large size as compared to hoscreen. Option for Image Resizer:

If you are using the tool mentioned in last step, Please look at the images. It has lots of options to resize image for our usage. We can easily enter the value of "height" or "width" in pixels!.

Once you have the image ready, next step is to convert the image to some form of numbers as actually all images are represented by array/matrix of numbers. Since we are not going to use SD card to save images or logos or icons as its irritating everytime to have a micro SD card for this purpose, we will now convert images to hexadecimal. Then we will store it in Arduino Flash Memory.

Using the LCD_Image_Converter tool, we will get the image in hexadecimal form.Load the image usign File->Open->"SelectUrImage" If you want to edit image, use the editing tools.

Copy all the numbers!! (Here each pixel is stored in its binary form as image is monochrome. If the pixel is filled, then it will be 1 or else it will be 0)

Other option is to go for colored images (remember that it takes lot of Arduino Flash memory). Based on the TFT screen you will have to select some options like color format (1.8" SPI TFT SR7735R uses 16 bit colors: R5G6B5)Load the image usign File->Open->"SelectUrImage" If you want to edit image, use the editing tools.

Copy all the numbers!! (Here each pixel is stored in a 16bit hexadecimal number. From LSB (lowest significant bit), first 5 represent "blue", then 6 digits represent "green" and rest 5 are for red.)

Case 2: Since there is no direct function in Adafruit GFX library, we will have to write our own code for this. We will have to traverse pixel by pixel to draw image/icon.

This type of icons are very useful for making automation systems having a display bar. Such icons provide intuitiveness to users for your projects or machines.

The display is driven by a ST7735R controller ( ST7735R-specifications.pdf (2.1 MB) ), can be used in a “slow” and a “fast” write mode, and is 3.3V/5V compatible.

Adafruit_ST7735 is the library we need to pair with the graphics library for hardware specific functions of the ST7735 TFT Display/SD-Card controller.

In the file dialog select the downloaded ZIP file and your library will be installed automatically. This will automatically install the library for you (requires Arduino 1.0.5 or newer). Restarting your Arduino software is recommended as it will make the examples visible in the examples menu.

The easiest way to remedy this is by extracting the GitHub ZIP file. Place the files in a directory with the proper library name (Adafruit_GFX, Adafruit_ST7735 or SD) and zip the folder (Adafruit_GFX, Adafruit_ST7735.zip, SD.zip). Now the Arduino software can read and install the library automatically for you.

Basically, besides the obvious backlight, we tell the controller first what we are talking to with the CS pins. CS(TFT) selects data to be for the Display, and CS(SD) to set data for the SD-Card. Data is written to the selected device through SDA (display) or MOSI (SD-Card). Data is read from the SD-Card through MISO.

So when using both display and SD-Card, and utilizing the Adafruit libraries with a SainSmart display, you will need to connect SDA to MOSI, and SCL to SCLK.

As mentioned before, the display has a SLOW and a FAST mode, each serving it’s own purpose. Do some experiments with both speeds to determine which one works for your application. Of course, the need of particular Arduino pins plays a role in this decision as well …

Note: Adafruit displays can have different colored tabs on the transparent label on your display. You might need to adapt your code if your display shows a little odd shift. I noticed that my SainSmart display (gree tab) behaves best with the code for the black tab – try them out to see which one works best for yours.

Low Speed display is about 1/5 of the speed of High Speed display, which makes it only suitable for particular purposes, but at least the SPI pins of the Arduino are available.

After connecting the display in Low Speed configuration, you can load the first example from the Arduino Software (“File” “Example” “Adafruit_ST7735” –  recommend starting with the “graphictest“).

Below the code parts for a LOW SPEED display (pay attention to the highlighted lines) – keep in mind that the names of the pins in the code are based on the Adafruit display:

The SD-Card needs to be FAT-16 or FAT-32 formatted, single partition, and the BMP file needs to be placed in the root (ie. not in a directory or anything like that).

You can name your BMP file “parrot.bmp” or modify the Sketch to have the proper filename (in “spitftbitmap” line 70, and in “soft_spitftbitmap” line 74).

#define SD_CS 4 // Chip select line for SD card#define TFT_CS 10 // Chip select line for TFT display#define TFT_DC 9 // Data/command line for TFT#define TFT_RST 8 // Reset line for TFT (or connect to +5V)

#define SD_CS 4 // Chip select line for SD card#define TFT_CS 10 // Chip select line for TFT display#define TFT_DC 9 // Data/command line for TFT#define TFT_RST 8 // Reset line for TFT (or connect to +5V)

As you have seen before the Adafruit_GFX library (supported by the Adafruit_ST7735 library) makes this easy for us – More information can be found at the GFX Reference page.

To use this in your Arduino Sketch: The first 2 characters represent RED, the second set of two characters is for GREEN and the last 2 characters represent BLUE. Add ‘0x’ in front of each of these hex values when using them (‘0x’ designates a hexadecimal value).

This function is used to indicate what corner of your display is considered (0,0), which in essence rotates the coordinate system 0, 90, 180 or 270 degrees.

However, if your application needs your screen sideways, then you’d want to rotate the screen 90 degrees, effectively changing the display from a 128×160 pixel (WxH) screen to a 160×128 pixel display. Valid values are: 0 (0 degrees), 1 (90 degrees), 2 (180 degrees) and 3 (270 degrees).

Based on these functions, I did create a little demo to show what these functions do. Either download the file or just copy the code and paste it into an empty Arduino Sketch.

tft.print("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur adipiscing ante sed nibh tincidunt feugiat. Maecenas enim massa, fringilla sed malesuada et, malesuada sit amet turpis. Sed porttitor neque ut ante pretium vitae malesuada nunc bibendum. Nullam aliquet ultrices massa eu hendrerit. Ut sed nisi lorem. In vestibulum purus a tortor imperdiet posuere. ");

With this article I kick off my series on the Arduino Esplora board. Today"s project is a nice (and cheap!) little digital picture frame that uses the Esplora"s TFT Screen add-on.

The Esplora board includes joystick, directional buttons, slider, RGB LED, temperature sensor. microphone, buzzer and accelerometer, all on-board, so it can work for lots of different projects. A screen is sold separately.

The official price for this board is currently $59.99 USD. The Chinese electronics stores on Ebay sell clones for much less, but you"ll have to wait several weeks for it to arrive.

The second component that you need is the Arduino TFT screen. This is a small 160x128 pixel 16-bit color display that plugs into a socket on the Esplora board. This screen also includes a micro-SD card slot that will give the Arduino board the ability to read and write files to SD cards.

The original Arduino brand of this screen costs $25, but it has been out of stock for a while. There are many clones on Amazon and Ebay that sell for the same or lower price.

Note: when you buy the screen make sure it is the kind that plugs into the Arduino Esplora, as there are other very similar screens that have different connectors.

The hardware preparations are really simple. The TFT screen plugs into the front socket of the Arduino Esplora. After you connect it you can power the board by connecting it to your computer using the USB cable.

If you are using a Windows PC you need to install drivers for your Arduino board. The process is explained in the Arduino documentation. If you are using Windows 8 there is an additional complication because the Arduino drivers aren"t signed by Microsoft and this version of Windows does not accept drivers that are not signed. The process to bypass the signed driver requirement is described in detail in this page.

Now it is time to install the Arduino Software. This software contains the tools to write and upload programs to your Arduino board. Make sure you install version 1.0.5 or newer.

With the Arduino board connected, launch the Arduino software. In the Tools menu open the Board submenu and make sure you select the Arduino Esplora from the list.

The setup() function contains instructions that initialize the Arduino. In the above example the serial port is initialized to run at 9600 bauds, and pin 13 is initialized as an output pin.

The loop() function contains the body of the program. This function is called over and over. In the example the function prints the message "Hello, world!" to the serial port, then gives power to pin 13, which on most Arduino boards turns an on-board LED on. The delay() function waits for the number of milliseconds given as argument, in this case half a second. After the delay the LED is turned off by removing power from pin 13, and then another wait of half a second is done. The cycle then repeats.

The TFT screen is controlled with the help of the TFT and SPI libraries that come with the Arduino software. Libraries contain utility functions that are generic and can be used by many programs.

The EsploraTFT object represents the screen. In the setup() function its begin() method is invoked to initialize the display. Then in loop() the background() method is called to change the color. The three arguments to background() are the red, green, blue components of the color, each a value from 0 to 255. The black variable declared near the top is used to alternate the colors each time loop() executes.

For this project images will be displayed on the screen. To have the most flexibility I have decided to write my own image drawing function, so the individual pixels need to be set one by one to the correct color, using the drawPixel() method. As an introductory example to pixel drawing, the following Arduino program draws a horizontal red line in the middle of the screen:

This program sets the background color of the screen in the setup() function. In loop() it obtains the dimensions of the screen in pixels and then uses a for-loop to draw the line of pixels.

The drawPixel() method takes three arguments. The first two are the column and row for the pixel to draw. The third argument is the color, which for this method is not given as three numbers for red, green and blue. Instead, the color is given as a single number in the internal 16-bit representation of the screen. The red and blue channels use 5 bits each, while the green channel uses 6 bits. The representation is as follows:

For example, the color red, which is represented in 24-bit RGB notation as red=255, green=0 and blue=0 is represented as the 16-bit binary number 0000 0000 1111 1000, or 0x00F8 in hexadecimal. A 50% red color would be 0000 0000 1000 0000, or 0x0080.

If this seems like an arbitrary representation consider that the Arduino has a little-endian CPU, so the two bytes are reversed when stored in memory. And now the five red bits appear first, followed by the six green bits and then the five blue bits.

If you search for other picture slideshows for the Arduino you will find that most, if not all, read the images in BMP format from a memory card installed in the SD slot in the back of the LCD screen. This requires you to convert the images, which you probably have as high resolution JPGs to 160x128 BMPs.

For this project I"ve decided to take a completely different approach. Instead of using the SD card as storage I take advantage of the serial connection between the Arduino and the computer. The Esplora acts as a server, it waits for the computer to send pictures to display over the serial port.

The following Python script runs on the computer connected to the Arduino and accomplishes the task of loading an image, scaling it to 160x128 while preserving the aspect ratio and finally sending it one pixel at a time over the serial port:

Finally, the function converts each pixel to the 16-bit format used by the Arduino TFT screen and sends each as two bytes over the serial connection, given as third argument to the function.

The character I is sent before the image data, to inform the Esplora that an image is coming. It is always a good idea to leave room for expansion in any communication protocol, so by adding a one byte prefix new commands can be added later.

The data sent over the serial port matches exactly the size of the screen, so the margins that were calculated before are used to generate black pixels that complete the picture.

In loop() the program waits until the is serial data available, and then reads one byte. If it is the I byte then it gets into a for-loop that iterates over all the rows in the image. For each row it reads the entire line of 16-bit pixels into a buffer. Once the entire line is stored an inner loop that iterates on the columns draws the pixels using drawPixel().

Why read all the pixels in a row before drawing them? Because it is more efficient to issue large reads. Reading pixels one by one and drawing them is slower because the cost of issuing a read does not scale directly to the size of the read, each read has a fixed cost associated with it, so the least amount of reads the more efficient the program will be.

Why read a line using a while loop? Because the serial port in the Arduino has a buffer of only 64 bytes, so a single read would never return more than that amount. An entire line has 160 pixels, which at 2 bytes per pixel make it a 320 byte buffer.

Copy/paste the above program into the Arduino software and upload it to your Esplora. Once the screen turns black the board is waiting for images sent from the computer.

Now you can run the Python script to send an image over, but first make sure you edit the bottom two lines to use the correct serial port number for your board and the path to a JPG image that you want to use:

If you connect the LCD screen to a different Arduino then you can run this program by removing the IS_ESPLORA definition at the top and setting the correct pin constants where the TFT object is initialized.

If you recall, images are prepended with an I character in the serial communication. This version of the Arduino program accepts a second command, prefixed with the letter C for "connect". When the client sends this command the Arduino responds by writing the width and height of the screen to the serial port. This is useful to make the client software independent of the hardware. If one day you install a larger screen then the client will not need to change, since the picture dimensions are discovered from the communication with the device.

The Python script, called client.py is given a folder in the command line arguments. During start up the script searches the folder and all its sub-folders for jpeg pictures. Random images found in this folder are uploaded periodically to the Arduino board, making it into a slideshow.

Note that the Uno is a bit slower than the Esplora, so I had to lower the baud rate to give it enough time to process the pixels. Another inconvenience is that many of the Arduinos (including the Uno) do a reset each time a serial connection is started or ended, and for this reason the first image is displayed after a delay that gives the board time to start up.

Now that TFT_eSPI has taken a good foot hold in LILYGO devices with LCD screens. It would be very useful to be able to render .png files. Else the driver is running the development of useful esp32 LCD based apps to be developed, down a dead end. Anyone achieved this yet? Or found a driver that can that works with an ST7789V with .png"s.This is way beyond my programming skills.