[EN] The MaixPy’s lcd class.

jarutex AI, display, English, MaixPy

This article discusses the use of the Sipeed M1W dock suit’s TFT-LCD module via the lcd class (MaixPy’s lcd class) built into the MaixPy, a module that allows programmers to use it with the efficiency of that class is high.

(Figure. 1 Sipeed M1W dock Suit’s screen)

lcd class

The lcd class is a class for interfacing with TFT that has a port to plug into the board. The items within the class are as follows:

object <module 'lcd'> is of type module
  __name__ -- lcd
  init -- <function>
  deinit -- <function>
  width -- <function>
  height -- <function>
  type -- <function>
  freq -- <function>
  set_backlight -- <function>
  get_backlight -- <function>
  display -- <function>
  clear -- <function>
  rotation -- <function>
  draw_string -- <function>
  fill_rectangle -- <function>
  XY_RLUD -- 0
  YX_RLUD -- 32
  XY_LRUD -- 64
  YX_LRUD -- 96
  XY_RLDU -- 128
  YX_RLDU -- 160
  XY_LRDU -- 192
  YX_LRDU -- 224
  BLACK -- 0
  NAVY -- 3840
  DARKGREEN -- 57347
  DARKCYAN -- 61187
  MAROON -- 120
  PURPLE -- 3960
  OLIVE -- 57467
  LIGHTGREY -- 6342
  DARKGREY -- 61307
  BLUE -- 7936
  GREEN -- 57351
  CYAN -- 65287
  RED -- 248
  MAGENTA -- 8184
  YELLOW -- 57599
  WHITE -- 65535
  ORANGE -- 8445
  GREENYELLOW -- 58799
  PINK -- 8184

Constant

These are constants for setting the display if the displayed display is reversed, such as alternating left characters. or on the bottom, etc.

  • XY_RLUD
  • YX_RLUD
  • XY_LRUD
  • YX_LRUD
  • XY_RLDU
  • YX_RLDU
  • XY_LRDU
  • YX_LRDU

Color value

The color values that the lcd class provides are as follows:

  • BLACK
  • NAVY
  • DARKGREEN
  • DARKCYAN
  • MAROON
  • PURPLE
  • OLIVE
  • LIGHTGREY
  • DARKGREY
  • BLUE
  • GREEN
  • CYAN
  • RED
  • MAGENTA
  • YELLOW
  • WHITE
  • ORANGE
  • GREENYELLOW
  • PINK

Commands

The command group of the lcd class is as follows.

init()

This is the command to start the display.

deinit()

It is a command to deactivate the display.

width()

It is a command to read the width of the display

height()

It is a command to read the height of the display

type()

Returns the display type. But at the moment it doesn’t support different types of displays.

  • 0 no display
  • 1 has display

freq()

For reading the clock frequency in the data transmission between the display and the board.

freq(freq_value)

For resetting the clock frequency as required

set_backlight( status )

If the status is True, it will turn on the TFT illumination, if false, it will turn off the illumination.

get_backlight()

It is a command to read the status of the TFT illumination LED.

display( img )

Bring the buffer values stored in the img to display on the display.

clear( color_value )

Clear the display with the specified color value. If not, it will be black.

rotation( x )

Rotate the screen.

draw_string(x,y,text, text_color, bg_color )

Displays text at position (x,y) with a given color.

fill_rectangle( x, y, w, h, color )

Draw a solid rectangle in the given color.

Example Code

lcd1.py

Example showing background color change with text display After that, rotate the display with rotation() and display the following message:

# lcd1.py - By: JarutEx - Sat Oct 2 2021

import lcd,time,sensor

if (lcd.type() == 0):
    print("Error : no lcd shield!")
    while (True):
        pass

lcd.freq(16000000)
lcd.init(color=(255,0,0))
colors = [
    lcd.BLACK,
    lcd.NAVY,
    lcd.DARKGREEN,
    lcd.DARKCYAN,
    lcd.MAROON,
    lcd.PURPLE,
    lcd.OLIVE,
    lcd.LIGHTGREY,
    lcd.DARKGREY,
    lcd.BLUE,
    lcd.GREEN,
    lcd.CYAN,
    lcd.RED,
    lcd.MAGENTA,
    lcd.YELLOW,
    lcd.WHITE,
    lcd.ORANGE,
    lcd.GREENYELLOW,
    lcd.PINK
]
lcd.set_backlight(True)
for color in colors:
    lcd.clear(color)
    lcd.draw_string(40,100,"JarutEx",lcd.WHITE,color)
    lcd.draw_string(40,120,"JarutEx",lcd.BLACK,color)
    time.sleep(1)
lcd.clear(lcd.RED)
lcd.rotation(0)
lcd.draw_string(30, 30, "JarutEx", lcd.WHITE, lcd.RED)
time.sleep(1)
lcd.rotation(1)
lcd.draw_string(60, 60, "JarutExy", lcd.WHITE, lcd.RED)
time.sleep(1)
lcd.rotation(2)
lcd.draw_string(120, 60, "JarutEx", lcd.WHITE, lcd.RED)
time.sleep(1)
lcd.rotation(3)
lcd.draw_string(120, 120, "JarutExy", lcd.WHITE, lcd.RED)
time.sleep(1)
if (lcd.get_backlight()):
    lcd.set_backlight( False )

In the first phase, changing the background color will result as shown in Figure 2, and the rotation of the display and display of the text will be as shown in Figure 3.

(Figure. 2 When changed the background)
(Figure. 3 When rotated and displayed text)

lcd2.py

An example of this program is to load a JPG image to display on the display by saving the image named pmai.jpg in the microSD. After that when powering the board, the board will report the availability of the microSD as shown in Figure 4, which means the card is ready to use.

(Figure. 4 When found microSD)

After that, test the operation by using the program lcd2 as follows to load the image with the command image.Image(“/sd/pmai.jpg”) and display the image with the command lcd.display( img ) will get the result as shown in Figure 5.

# lcd2 - By: JaritEx - Sun Oct 3 2021

import image, time, lcd

clock = time.clock()
print("lcd freq. = {}Hz".format(lcd.freq()))
lcd.freq(80000000)
lcd.init(color=(255,0,0))
img = image.Image("/sd/pmai.jpg")

while(True):
    clock.tick()
    lcd.display(img)
(Figure. 5 Result of lcd2.py)

Conclusion

From this article, you will find that MaixPy does not have a very basic set of commands that can be displayed. This is because the image processing instruction is mainly in the image class, however, it will be found that with the LCD instruction set, it is enough to display at a considerable speed and enough for basic use. Finally, have fun with programming.

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(C) 2020-2021, By Jarut Busarathid and Danai Jedsadathitikul
Updated 2021-12-22