micropython lcd display brands

In this tutorial Tony Goodhew explains how to use the basic graphics procedures which are included in the display driver, and for the ambitious makers out there he also provides examples for advanced shapes and graphics!

All the other graphical and text objects we would like to display can be built from this single pixel instruction; such as lines, circles, rectangles, triangles and text strings at different sizes.

This is all carried out with code. Display manufacturers usually supply some of these procedures/methods but leave the rest up to the end user to construct.

At the top of our driver program we will always import a minimal set of libraries using this block at the top of our MicroPython script (we add even more later when we want to do advanced programs):

The third line here imports the Framebuffer library which includes several very useful routines to draw objects on the display. The garbage collection library, gc, has also been imported so that we can check how much memory is available.

The following methods draw shapes (such as those above) onto the FrameBuffer. They only become visible to the user once the lcd.show() instruction is executed.

Each program contains the screen driver code, sets up the buttons/joystick (if applicable), sets the width and height variables, loads the essential libraries, defines the colour (R, G, B) and clear (c) procedures, then displays some colour checking text like this:

Using lcd.fill_rect, fill the whole screen green and then fill the middle of the screen black, leaving a 10 pixel border. Put red 10-pixel squares in each corner.

Draw a dark grey rectangle in the centre of the screen. Draw 500 white pixels inside the square, none touching the edge. (Random was explained in the previous display tutorial.)

This is routine is very complicated. It splits the original triangle into two with a horizontal line and then fills them in. If you uncomment all the # lcd.show() lines and sleep instructions it will slow right down and you can see it working (unfortunately, the 2” display needs such a large buffer that there is not enough memory for the filled triangles code):

For the imports we added the math library as this is needed for Sin and Cos in graph plotting. The random library has also been imported, for the randomly generated triangles. These are followed by the basic LCD board setup we covered earlier.

In the centre of the screen display a ‘bull’s eye’ circular target with a ‘gold’ centre, 4 other colours and scores 10, 8, 6, 4 and 2 written in the appropriate positions.

You may have noticed that on some screens the text is very small and difficult to read. In a following tutorial will add an extra font, with more characters, which we can display in different sizes.

This article was written by Tony Goodhew. Tony is a retired teacher of computing who starting writing code back in 1968 when it was called programming - he started with FORTRAN IV on an IBM 1130! An active Raspberry Pi community member, his main interests now are coding in MicroPython, travelling and photography.

LCD screens are useful and found in many parts of our life. At the train station, parking meter, vending machines communicating brief messages on how we interact with the machine they are connected to. LCD screens are a fun way to communicate information in Raspberry Pi Pico projects and other Raspberry Pi Projects. They have a big bright screen which can display text, numbers and characters across a 16 x 2 screen. The 16 refers to 16 characters across the screen, and the 2 represents the number of rows we have. We can get LCD screens with 20x2, 20x4 and many other configurations, but 16x2 is the most common.

In this tutorial, we will learn how to connect an LCD screen, an HD44780, to a Raspberry Pi Pico via the I2C interface using the attached I2C backpack, then we will install a MicroPython library via the Thonny editor and learn how to use it to write text to the display, control the cursor and the backlight.

2. Import four librariesof pre-written code. The first two are from the Machine library and they enable us to use I2C and GPIO pins. Next we import the sleep function from Time enabling us to pause the code. Finally we import the I2C library to interact with the LCD screen.from machine import I2C, Pin

3. Create an objecti2c to communicate with the LCD screen over the I2C protocol. Here we are using I2C channel 0, which maps SDA to GP0 and SCL to GP1.i2c = I2C(0, sda=Pin(0), scl=Pin(1), freq=400000)

5. Create an objectlcdto set up the I2C connection for the library. It tells the library what I2C pins we are using, set via the i2c object, the address of our screen, set via I2C_ADDRand finally it sets that we have a screen with two rows and 16 columns.lcd = I2cLcd(i2c, I2C_ADDR, 2, 16)

6. Create a loopto continually run the code, the first line in the loop will print the I2C address of our display to Thonny’s Python Shell.while True:

8. Write two lines of textto the screen. The first will print “I2C Address:” followed by the address stored inside the I2C_ADDR object. Then insert a new line character “\n” and then write another line saying “Tom’s Hardware" (or whatever you want it to say). Pause for two seconds to allow time to read the text.lcd.putstr("I2C Address:"+str(I2C_ADDR)+"\n")

9. Clear the screenbefore repeating the previous section of code, but this time we display the I2C address of the LCD display using its hex value. The PCF8574T chip used in the I2C backpack has two address, 0x20 and 0x27 and it is useful to know which it is using, especially if we are using multiple I2C devices as they may cause a clash on the bus.lcd.clear()

12. Turn the backlight back onand then hide the cursor. Sometimes, a flashing cursor can detract from the information we are trying to communicate.lcd.backlight_on()

13. Create a for loopthat will print the number 0 to 19 on the LCD screen. Note that there is a 0.4 second delay before we delete the value and replace it with the next. We have to delete the text as overwriting the text will make it look garbled.for i in range(20):

Save and runyour code. As with any Python script in Thonny, Click on File >> Saveand save the file to your Raspberry Pi Pico. We recommend calling it i2c_lcd_test.py. When ready, click on the Green play buttonto start the code and watch as the test runs on the screen.

Please take care of the direction when you connect Pico, an USB port is printed to indicate. You can also check the pin of Pico and the LCD board when connecting.

3. Please refer to the official micropython document to set up the environment, and select the Raspberry Pi Pico device in Thonny"s Tools->Options->Interprete. As shown below:

3. To configure the driver file, open the Arduino library file directory, usually in C:\Users\xxxx\Documents\Arduino\libraries\TFT_eSPI\ , for ResTouch-LCD-3.5, put the TFT_eSPI library (User_Setups\Setup60_RP2040_ILI9341.h) (User_Setup_Select.h) ) with the files in the sample program folder Arduino\ResTouch-LCD-3.5, and the same for ResTouch-LCD-2.8, as shown in the figure.

The C demo is for Pico-ResTouch-LCD-2.8 and Pico-ResTouch-LCD-3.5. In the main function, we place the three main functions in order and place TP_DrawBoard(); in an infinite loop to achieve the above function.

Note that if you want to test the LCD_ShowBMP example, you need to copy the picture from the PIC folder to the root directory of a micro SD card, and insert the SD card into the slot in the backside of the LCD. Then run the examples.

The micro SD card should in FAT format, and the resolution of the pictures used should be the same as the LCD, for a 2.8inch LCD, it is 320 × 240， and 480 × 320 for a 3.5inch LCD. 24bit BMP.

The LCD controller is ILI9488, we need to initialize the controller at the first, which is done in LCD_Driver.c file, and being called in lcd_test.c file.

In the example, this demo shows that the BMP picture first reads the picture data in the BMP format on the SD card through the SPI protocol and displays it.

These functions are written in LCD_Bmp.c, actually read the picture data in the BMP format with a specific file name from the SD card and then call the display function written by ourselves to "express" the data as an image again.

i have a d-series pyboard with an lcd1602 display... i am following the documentation at https://pybd.io/hw/pybd_sfxw.html, and http://docs.micropython.org/en/latest/library/pyb.I2C.html, but i am not getting any results.

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