OLED/LCD HAT (A)

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OLED/LCD HAT (A)
OLED-LCD HAT (A).jpg

I2C, SPI
240×320, 128×64
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Overview

Introduction

The OLED/LCD HAT (A) features a 2-inch IPS screen with the built-in ST7789VW driver and support using SPI communication. Also, it boasts a wide viewing angle and supports a 262K color display with 240x320 resolution. Dual 0.96-inch OLED screen with a built-in driver, support using I2C communication, and blue display with 128x64 resolution for displaying key information, status indicator, or mini graphics. In addition, we provide demos for Raspberry Pi (BCM2835 library, WiringPi library, and Python demo), STM32, and Arduino.

Parameters

Parameter Name Parameters
Power Supply 3.3V
Operating Current 840mA
Dimensions 65.00 x 56.00(mm)
Screen 0.96inch OLED 2inch IPS
Driver SSD1315 ST7789
Communication Interface I2C 4-wire SPI
Resolution 128 × 64 240 × 320
Display Size 21.74mm × 11.20mm 30.60mm × 40.80mm
Pixel Size 0.15mm × 0.15mm 0.0975mm× 0.0975mm

Pins

Pins Board
VCC 3.3V
GND GND
MOSI 19
SCLK 23
CS 24
DC 15
RST 13
SDA 3
SCL 5
KEY1 7
KEY2 11
KEY3 16
KEY4 18

Hardware Description

Communication Protocol

0.96inch lcd module spi.png
From the above, we know that 4-wire SPI communication is used, and we can get the following communication timing diagram by checking the datasheet to transmit RGB556 as an example:
Note: Different from the traditional SPI protocol, the data line from the slave to the master is hidden since the device only has a display requirement.
RESX Is the reset pin, it should be low when powering the module and be higher at other times.
CSX is slave chip select, when CS is low, the chip is enabled.
D/CX is data/command control pin, when DC = 0, write command, when DC = 1, write data
SDA is the data pin for transmitting RGB data, it works as the MOSI pin of the SPI interface;
SCL works the SCLK pins of the SPI interface.
SPI communication has data transfer timing, which is combined by CPHA and CPOL.
The high or low CPHA determines whether the serial synchronization clock is used for data acquisition at the first or second clock tick edge; when CPHA = 0, data acquisition is performed at the first tick edge.
CPOL determines the level of the serial synchronous clock at an idle state. When CPOL = 0, the level is Low. However, CPOL has little effect on the transmission.
CPHA determines whether data is collected at the first clock edge or at the second clock edge of the serial synchronous clock; when CPHL = 0, data is collected at the first clock edge.
As can be seen from the figure, when the first falling edge of SCLK starts transmitting data, a clock cycle to transmit 8-bit data, the use of SPI0, bit-by-bit transmission, the high bit in the front, the low bit in the back.

  • I2C communication:

The 7-bit device addresses of the SSD1315 chip are conveniently 0x1E and 0x1F, that is, the device write addresses are 0x3C and 0x3D, and the read addresses are 0x3D and 0x3E.

  • Waveform Description:
    • Write a single byte: (write 0x01 to 0x1F register)
    • 1.28inch Touch LCD02.jpg
    • Write multiple bytes consecutively (write 0x20, 0x01 to 0x1E and 0x1F respectively)
    • 1.28inch Touch LCD03.jpg
    • Read a single byte (read a single byte from 0x21)
    • 1.28inch Touch LCD04.jpg
    • Read multiple bytes consecutively (read 3 bytes from 0x21, 0x22, 0x23)
    • 1.28inch Touch LCD05.jpg

Working with Raspberry Pi

Enable SPI interface

PS: If you are using a system with a Bullseye branch, you need to change "apt-get" to "apt", and the system of the Bullseye branch only supports Python3.
  • Open the terminal, and use the command to enter the configuration page.
sudo raspi-config
Choose Interfacing Options -> SPI -> Yes  to enable the SPI interface

RPI open spi.png
Reboot Raspberry Pi:

sudo reboot

Make sure that the SPI is not occupied by other devices, you can check in the middle of the /boot/config .txt.
For I2C, enter the configuration interface and select Interface Options -> I2C -> Yes to enable the IIC interface, and then reboot.

Install Library

If you use the bookworm system, you can only use lgpio library, bcm2835 and wiringPi can't be installed and used.

BCM2835

#Open the Raspberry Pi terminal and run the following command
wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.71.tar.gz
tar zxvf bcm2835-1.71.tar.gz 
cd bcm2835-1.71/
sudo ./configure && sudo make && sudo make check && sudo make install
# For more, you can refer to the official website at: http://www.airspayce.com/mikem/bcm2835/

WiringPi

#Open the Raspberry Pi terminal and run the following command
cd
sudo apt-get install wiringpi
#For Raspberry Pi systems after May 2019 (earlier than that can be executed without), an upgrade may be required:
wget https://project-downloads.drogon.net/wiringpi-latest.deb
sudo dpkg -i wiringpi-latest.deb
gpio -v
# Run gpio -v and version 2.52 will appear, if it doesn't it means there was an installation error

# Bullseye branch system using the following command:
git clone https://github.com/WiringPi/WiringPi
cd WiringPi
. /build
gpio -v
# Run gpio -v and version 2.70 will appear, if it doesn't it means there was an installation error

lgpio

#Open the Raspberry Pi terminal and run the following command
wget https://github.com/joan2937/lg/archive/master.zip
unzip master.zip
cd lg-master
sudo make install

# You can refer to the official website for more: https://github.com/gpiozero/lg

Python

#python2
sudo apt-get update
sudo apt-get install python-pip
sudo apt-get install python-pil
sudo apt-get install python-numpy
sudo pip install RPi.GPIO
sudo pip install spidev
#python3
sudo apt-get update
sudo apt-get install python3-pip
sudo apt-get install python3-pil
sudo apt-get install python3-numpy
sudo -H pip3 install --upgrade luma.oled
sudo -H pip3 install --upgrade luma.lcd
sudo pip3 install RPi.GPIO
sudo pip3 install spidev

Download Test Demo

Open the Raspberry Pi terminal and run the following:

sudo apt-get install unzip -y
sudo wget https://files.waveshare.com/wiki/OLED-LCD-HAT-A/OLED_LCD_HAT_A_Demo.zip
sudo unzip ./OLED_LCD_HAT_A_Demo.zip
cd OLED_LCD_HAT_A_Demo 

Run Test Demo

The following commands should be run on the Raspberry Pi, otherwise, the directory can not be indexed. (BCM2835 library is not used in this demo).

C

  • Recompile and it may take a few seconds:
cd c
sudo make clean
sudo make -j 8
  • Run the example demo:
# Run the 0.96-inch screen respectively:
sudo ./main 0.96

#Run the 2-inch screen respectively:
sudo ./main 2
 
#Run the 0.96-inch screen and 2-inch screen:
sudo ./main all

#Run the key demo:
sudo ./main key

Python

  • Enter the Python demo directory:
cd ..
cd python
  • Run the example demo:
#Run two 0.96-inch screens simultaneously
sudo python double_oled.py

#Run two 0.96-inch screens with the address of 0x3C separately:
sudo python test_0x3C.py
 
#Run two 0.96-inch screens with the 0x3D address separately:
sudo python test_0x3D.py

##Run the 2inch screen:
sudo python3 test_2inch.py

#Run the key demo:
sudo python key_demo.py

FPCP Porting

Download Drives

Open the Raspberry Pi terminal and execute:

sudo apt-get install unzip -y
sudo apt-get install cmake -y
sudo wget https://files.waveshare.com/wiki/OLED-LCD-HAT-A/OLED_LCD_HAT_A.zip
sudo unzip ./OLED_LCD_HAT_A.zip
sudo cp OLED_LCD_HAT_A.dtbo /boot/overlays/
sudo wget https://files.waveshare.com/wiki/OLED-LCD-HAT-A/Rpi-fbcp.zip
sudo unzip ./Rpi-fbcp.zip
cd rpi-fbcp/
sudo mkdir build
cd build
sudo cmake ..
sudo make -j8
sudo install fbcp /usr/local/bin/fbcp
sudo ./fbcp

Edit the config.txt file:

sudo nano /boot/config.txt

Please block the following sentence:
FBCP CLOSE.jpg
Add the following code at the end of config.txt:

dtparam=spi=on
dtoverlay=OLED_LCD_HAT_A

hdmi_force_hotplug=1
max_usb_current=1
hdmi_group=2
hdmi_mode=1
hdmi_mode=87
hdmi_cvt 640 480 60 6 0 0 0
hdmi_drive=2
display_rotate=0

Set up to Boot Automatically

sudo cp ~/rpi-fbcp/build/fbcp /usr/local/bin/fbcp
sudo nano /etc/rc.local

Add fbcp& in front of exit 0. Be sure to add the "&" and run it in the background, otherwise, the system may not boot.
1in3 lcd fb5.png
A reboot is then required:

sudo reboot

After rebooting, it can normally displays.

API (Please choose C/Python to read)

Raspberry Pi series can all share a common set of programs as they are embedded systems with better compatibility.
The demo is divided into the bottom hardware interface, the middle layer LCD driver, and the upper layer application.

C

Bottom Hardware Interface

We have carried out the low-level encapsulation, if you need to know the internal implementation can go to the corresponding directory to check, for the reason that the hardware platform and the internal implementation are different. You can open DEV_Config.c(.h) to see definitions, which are in the directory RaspberryPi\c\lib\Config.

1. There are three ways for C to drive: BCM2835 library, WiringPi library, and Dev library respectively
2. We use Dev libraries by default. If you need to change to  BCM2835 or WiringPi libraries, please open RaspberryPi\c\Makefile and modify lines 13-15 as follows:  

RPI open spi1.png

  • Data type:
#define UBYTE      uint8_t
#define UWORD      uint16_t
#define UDOUBLE    uint32_t
  • Module initialization and exit processing.
UBYTE DEV_ModuleInit(void);
void  DEV_ModuleExit(void);
Note: 
  Here is some GPIO processing before and after using the LCD screen.
  • GPIO read and write:
void 	DEV_Digital_Write(UWORD Pin, UBYTE Value);
UBYTE 	DEV_Digital_Read(UWORD Pin);
  • SPI writes data:
void DEV_SPI_WriteByte(UBYTE Value);

Upper Application

If you need to draw pictures, display Chinese and English characters, display pictures, etc., we provide some basic functions here about some graphics processing in the directory RaspberryPi\c\lib\GUI\GUI_Paint.c(.h).
LCD rpi GUI.png
The fonts can be found in RaspberryPi\c\lib\Fonts directory.
RPI open spi3.png

  • New Image Attribute: Create a new image attribute including the name of the image cache, width, height, flip angle, and color.
void Paint_NewImage(UBYTE *image, UWORD Width, UWORD Height, UWORD Rotate, UWORD Color)
Parameters:
 	   image: the name of the image cache, which is actually a pointer to the first address of the image cache;
 	   Width: the width of the image cache;
 	   Height: the height of the image cache;
 	   Rotate: the flipping angle of the image;
 	   Color: the initial color of the image;
  • Select Image Cache: Select Image Cache for creating multiple image attributes, the image cache can exist more than one, you can select each image you create.
void Paint_SelectImage(UBYTE *image)
Parameters:
 	   image: the name of the image cache, which is actually a pointer to the first address of the image cache;
  • Image rotation: set the rotation angle of the selected image. It is recommended to use it after Paint_SelectImage(), and you can choose to rotate 0, 90, 180, or 270.
void Paint_SetRotate(UWORD Rotate)
Parameters:
 	   Rotate: the rotation angle of the selected image. You can choose ROTATE_0, ROTATE_90, ROTATE_180, and ROTATE_270 corresponding to 0, 90, 180, and 270 degrees.

[Note] Under different selection angles, the coordinates correspond to different starting pixel points. Here take 1.14 as an example, four pictures in the order of 0 °, 90 °, 180 °, and 270 °for reference:
Image-rotate.png

  • Image mirror flip: Set the mirror flip of the selected image. You can choose no mirror, horizontal mirror, vertical mirror, or image center mirror.
void Paint_SetMirroring(UBYTE mirror)
Parameters:
 	   mirror: indicates the image mirroring mode. MIRROR_NONE, MIRROR_HORIZONTAL, MIRROR_VERTICAL, MIRROR_ORIGIN correspond to no mirror, horizontal mirror, vertical mirror, and image center mirror respectively.
  • Set points of the display position and color in the buffer: here is the core GUI function, processing points display position and color in the buffer.
void Paint_SetPixel(UWORD Xpoint, UWORD Ypoint, UWORD Color)
Parameters:
 	   Xpoint: X position of the point in the image cache
  	   Ypoint: Y position of the point in the image cache
 	   Color: Display the point color
  • Image buffer fill color: Fills the image buffer with a color, usually used to flash the screen into blank.
void Paint_Clear(UWORD Color)
Parameters:
           Color: fill Color
  • The fill color of a certain window in the image buffer: the image buffer part of the window filled with a certain color, usually used to fresh the screen into blank, often used for time display, fresh the last second of the screen.
void Paint_ClearWindows(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend, UWORD Color)
Parameters:
           Xstart: the x-starting coordinate of the window
           Ystart: the y-starting coordinate of the window
           Xend: the x-end coordinate of the window
           Yend: the y-end coordinate of the window
           Color: fill Color
  • Draw point: In the image buffer, draw points on (Xpoint, Ypoint), you can choose the color, the size of the point, and the style of the point.
void Paint_DrawPoint(UWORD Xpoint, UWORD Ypoint, UWORD Color, DOT_PIXEL Dot_Pixel, DOT_STYLE Dot_Style)
Parameters:
           Xpoint: indicates the X coordinate of a point.
           Ypoint: indicates the Y coordinate of a point.
           Color: fill Color
           Dot_Pixel: The size of the dot, the demo provides 8 size points by default.
                      typedef enum {
                              DOT_PIXEL_1X1  = 1,	// 1 x 1
                              DOT_PIXEL_2X2,    	// 2 X 2
                              DOT_PIXEL_3X3, 	 	// 3 X 3
                              DOT_PIXEL_4X4, 	 	// 4 X 4
                              DOT_PIXEL_5X5, 		// 5 X 5
                              DOT_PIXEL_6X6, 		// 6 X 6
                              DOT_PIXEL_7X7, 		// 7 X 7
                              DOT_PIXEL_8X8, 		// 8 X 8
               } DOT_PIXEL;
        Dot_Style: the size of a point that expands from the center of the point or from the bottom left corner of the point to the right and up.
                   typedef enum {
                     DOT_FILL_AROUND  = 1,
                     DOT_FILL_RIGHTUP,
                  } DOT_STYLE;
  • Draw the line: In the image buffer, draw a line from (Xstart, Ystart) to (Xend, Yend), you can choose the color, the width, and the style of the line.
void Paint_DrawLine(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend, UWORD Color, LINE_STYLE Line_Style, LINE_STYLE Line_Style)
Parameters:
           Xstart: the x-starting coordinate of a line
           Ystart: the y-starting coordinate of a line
           Xend: the x-end coordinate of a line
           Yend: the y-end coordinate of a line
           Color: fill Color
           Line_width: The width of the line, the demo provides 8 sizes of width by default.
                 typedef enum {
                         DOT_PIXEL_1X1=1,	// 1 x 1
                         DOT_PIXEL_2X2, 	// 2 X 2
                         DOT_PIXEL_3X3,		// 3 X 3
                         DOT_PIXEL_4X4,		// 4 X 4
                         DOT_PIXEL_5X5,		// 5 X 5
                         DOT_PIXEL_6X6, 	// 6 X 6
                         DOT_PIXEL_7X7, 	// 7 X 7
                         DOT_PIXEL_8X8,		// 8 X 8
              } DOT_PIXEL;
        Line_Style: line style. Select whether the lines are joined in a straight or dashed way.
              typedef enum {
                 LINE_STYLE_SOLID = 0,
                 LINE_STYLE_DOTTED,
              } LINE_STYLE;
  • Draw a rectangle: In the image buffer, draw a rectangle from (Xstart, Ystart) to (Xend, Yend), you can choose the color, the width of the line, and whether to fill the inside of the rectangle.
void Paint_DrawRectangle(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend, UWORD Color, DOT_PIXEL Line_width, DRAW_FILL Draw_Fill)
Parameters:
	   Xstart: the starting X coordinate of the rectangle
	   Ystart: the starting Y coordinate of the rectangle
	   Xend: the x-end coordinate of the rectangle
           Yend: the y-end coordinate of the rectangle
	   Color: fill Color
	    Line_width: The width of the four sides of a rectangle. And the demo provides 8 sizes of width by default.
		     typedef enum {
			     DOT_PIXEL_1X1 = 1,	        // 1 x 1
			     DOT_PIXEL_2X2, 		// 2 X 2
			     DOT_PIXEL_3X3,		// 3 X 3
			     DOT_PIXEL_4X4,	        // 4 X 4
			     DOT_PIXEL_5X5, 		// 5 X 5
 			     DOT_PIXEL_6X6, 		// 6 X 6
                             DOT_PIXEL_7X7, 		// 7 X 7
                             DOT_PIXEL_8X8, 		// 8 X 8
                 } DOT_PIXEL;
         Draw_Fill: Fill, whether to fill the inside of the rectangle
                typedef enum {
                 	DRAW_FILL_EMPTY = 0,
                 	DRAW_FILL_FULL,
              } DRAW_FILL;
  • Draw a circle: In the image buffer, draw a circle of Radius with (X_Center Y_Center) as the center. You can choose the color, the width of the line, and whether to fill the inside of the circle.
void Paint_DrawCircle(UWORD X_Center, UWORD Y_Center, UWORD Radius, UWORD Color, DOT_PIXEL Line_width, DRAW_FILL Draw_Fill)
Parameters:
	   X_Center: the x coordinate of the center of the circle
	   Y_Center: the y coordinate of the center of the circle
	   Radius: indicates the radius of a circle
	   Color: fill Color
	   Line_width: The width of the arc, with a default of 8 widths
		typedef enum {
        		DOT_PIXEL_1X1  = 1,	// 1 x 1
        		DOT_PIXEL_2X2  , 		// 2 X 2
        		DOT_PIXEL_3X3  ,		// 3 X 3
        		DOT_PIXEL_4X4  ,		// 4 X 4
        		DOT_PIXEL_5X5  , 		// 5 X 5
        		DOT_PIXEL_6X6  , 		// 6 X 6
        		DOT_PIXEL_7X7  , 		// 7 X 7
        		DOT_PIXEL_8X8  , 		// 8 X 8
		} DOT_PIXEL;
	  Draw_Fill: fill, whether to fill the inside of the circle
               typedef enum {
              		DRAW_FILL_EMPTY = 0,
                 	DRAW_FILL_FULL,
              } DRAW_FILL;
  • Write Ascii character: In the image buffer, use (Xstart Ystart) as the left vertex, and write an Ascii character, you can select Ascii visual character library, font foreground color, and font background color.
void Paint_DrawChar(UWORD Xstart, UWORD Ystart, const char Ascii_Char, sFONT* Font, UWORD Color_Foreground,  UWORD Color_Background)
Parameters:
	   Xstart: Character's left-top point X-coordinate
	   Ystart: Character's left-top point Y-coordinate
	   Ascii_Char: indicates the Ascii character
	   Font: Ascii visual character library, in the Fonts folder the demo provides the following Fonts:
  		 Font8: 5*8 font
    		 Font12: 7*12 font
    		 Font16: 11*16 font
    		 Font20: 14*20 font
    		 Font24: 17*24 font
  	  Color_Foreground: Font color
  	  Color_Background: indicates the background color
  • Write English string: In the image buffer, use (Xstart Ystart) as the left-top point, and write a string of English characters, you can choose Ascii visual character library, font foreground color, or font background color.
void Paint_DrawString_EN(UWORD Xstart, UWORD Ystart, const char * pString, sFONT* Font, UWORD Color_Foreground,  UWORD Color_Background)
Parameters:
	  Xstart: Character's left-top point X-coordinate
	  Ystart: Character's left-top point Y-coordinate
	  PString: string, string is a pointer
	  Font: Ascii visual character library, in the Fonts folder the demo provides the following Fonts:
     		Font8: 5*8 font
     		Font12: 7*12 font
     		Font16: 11*16 font
     		Font20: 14*20 font
     		Font24: 17*24 font
	  Color_Foreground: Font color
  	  Color_Background: indicates the background color
  • Write Chinese string: in the image buffer, use (Xstart Ystart) as the left-top point, and write a string of Chinese characters, you can choose character font, font foreground color, and font background color of the GB2312 encoding.
void Paint_DrawString_CN(UWORD Xstart, UWORD Ystart, const char * pString, cFONT* font, UWORD Color_Foreground, UWORD Color_Background)
Parameters:
	  Xstart: Character's left-top point X-coordinate
	  Ystart: Character's left-top point Y-coordinate
	  PString: string, string is a pointer
  	  Font: GB2312 encoding character Font library, in the Fonts folder the demo provides the following Fonts:
     		Font12CN: ASCII font 11*21, Chinese font 16*21
     		Font24CN: ASCII font24 *41, Chinese font 32*41
	  Color_Foreground: Font color
	  Color_Background: indicates the background color
  • Write numbers: In the image buffer, use (Xstart Ystart) as the left-top point, and write a string of numbers, you can choose Ascii visual character library, font foreground color, or font background color.
void Paint_DrawNum(UWORD Xpoint, UWORD Ypoint, int32_t Nummber, sFONT* Font, UWORD Color_Foreground, UWORD Color_Background)
Parameters:
 	  Xstart: Character's left-top point X-coordinate
 	  Ystart: Character's left-top point Y-coordinate
 	  Nummber: the number displayed here is saved as a 32-bit int type, which can be displayed up to 2147483647.
 	  Font: Ascii code visual character font, the following fonts are provided in the Fonts folder:
 	 	font8: 5*8 font
 	 	font12: 7*12 font
 	 	font16: 11*16 font
 	 	font20: 14*20 font
 	 	font24: 17*24 font
 	Color_Foreground: font color
 	Color_Background: background color
  • Write numbers with decimals: In the image buffer, at (Xstart, Ystart) as the left-top point, write a series of numbers with decimals. You can select the ASCII code visual character library, font foreground color, and font background color.
void Paint_DrawFloatNum(UWORD Xpoint, UWORD Ypoint, double Nummber, UBYTE Decimal_Point, sFONT* Font, UWORD Color_Foreground, UWORD  Color_Background);
Parameters:
 	   Xstart: Character's left-top point X-coordinate
 	   Ystart: Character's left-top point Y-coordinate
 	   Nummber: Displayed numbers, here stored as double type, are sufficient for common requirements
           Decimal_Point: Displaying digits after the decimal point
 	   Font: ASCII code visual character library includes the following fonts in the Fonts folder
 	 	font8: 5*8 font
 	 	font12: 7*12 font
 	 	font16: 11*16 font
 	 	font20: 14*20 font
 	 	font24: 17*24 font
 	   Color_Foreground: font color
 	   Color_Background: background color
  • Display time: In the image buffer, at (Xstart, Ystart) as the left-top point, display a time duration. You can choose the ASCII code visual character library, font foreground color, and font background color.
void Paint_DrawTime(UWORD Xstart, UWORD Ystart, PAINT_TIME *pTime, sFONT* Font, UWORD Color_Background, UWORD Color_Foreground)
Parameters:
 	   Xstart: Character's left-top point X-coordinate
 	   Ystart: Character's left-top point Y-coordinate
 	   pTime: The displayed time is defined using a time structure. You can pass individual digits for hours, minutes, and seconds as parameters;
 	   Font:  ASCII code visual character library, with the following fonts available in the Fonts folder;
 	 	font8: 5*8 font
 	 	font12: 7*12 font
 	 	font16: 11*16 font
 	 	font20: 14*20 font
 	 	font24: 17*24 font
 	   Color_Foreground: font color
 	   Color_Background: background color
  • Read local BMP images and write them to a buffer.

This is possible for Raspberry Pi and other Linux-based operating systems.
For Raspberry Pi, you can refer to the directory: RaspberryPi\c\lib\GUI\GUI_BMPfile.c(.h).

UBYTE GUI_ReadBmp(const char *path, UWORD Xstart, UWORD Ystart)
Parameters:
	   path: the corresponding path of BMP pictures  
 	   Xstart: The X-coordinate of the left-top point of the image is typically passed as 0 by default.
 	   Ystart: The Y-coordinate of the left-top point of the image is typically passed as 0 by default.

Python (For Raspberry Pi)

It is for Python and Python3.
For Python, its invocation doesn't involve the complexity of C.

lcdconfig.py

  • Module initialization and exit processing.
def module_init()
def module_exit()
Note:
1. Here is some GPIO processing before and after using the LCD screen.
2. The module_init() function is automatically called in the INIT () initializer on the LCD, but the module_exit() function needs to be called by itself
  • GPIO read and write:
def  digital_write(pin, value)
def  digital_read(pin)
  • SPI write data.
def spi_writebyte(data)

About Rotation Settings

If you need to set the screen rotation in the python program, you can set it by the statement im_r= image1.rotate(270).

im_r= image1.rotate(270)
Rotation effect, take 1.14 as an example, the order is 0°, 90°, 180°, 270°
Image-rotate.png

GUI Functions

Python has an image library PIL official library link, it does not need to write code from the logical layer like C and can directly call the image library for image processing. The following will take a 1.54-inch LCD as an example, we provide a brief description of the demo.

  • It needs to use the image library and install the library.
sudo apt-get install python3-pil  

And then import the library

from PIL import Image,ImageDraw,ImageFont.

Among them, Image is the basic library, ImageDraw is the drawing function, and ImageFont is the text function.

  • Define an image cache to facilitate drawing, writing and other functions on the picture
image1 = Image.new("RGB", (disp.width, disp.height), "WHITE")

The first parameter defines the color depth of the image, which is defined as "1" to indicate the bitmap of one-bit depth. The second parameter is a tuple that defines the width and height of the image. The third parameter defines the default color of the buffer, which is defined as "WHITE".

  • Create a drawing object based on Image1 on which all drawing operations will be performed on here.
draw = ImageDraw.Draw(image1)
  • Draw line.
draw.line([(20, 10),(70, 60)], fill = "RED",width = 1)

The first parameter is a 4-element tuple, with (20, 10) as the starting point and (70, 60) as the ending point, to draw a straight line. fill="RED" indicates that the line is red in color, and width=1 specifies a line width of 1 pixel.

  • Draw a rectangle.
draw.rectangle([(20,10),(70,60)],fill = "WHITE",outline="BLUE")

The first parameter is a 4-element tuple, with (20, 10) as the coordinates of the upper-left corner of the rectangle, and (70, 60) as the coordinates of the lower-right corner of the rectangle. fill="WHITE" specifies that the interior is filled with white color, and outline="BLUE" indicates that the outer border is blue.

  • Draw a circle.
draw.arc((150,15,190,55),0, 360, fill =(0,255,0)

Draw an inscribed circle in the square, the first parameter is a tuple of 4 elements, with (150, 15) as the upper left corner vertex of the square, (190, 55) as the lower right corner vertex of the square, specifying the level median line of the rectangular frame is the angle of 0 degrees, the second parameter indicates the starting angle, the third parameter indicates the ending angle, and fill = (0,255,0) indicates that the color of the line is green. If the figure is not square according to the coordination, you will get an ellipse.

Besides the arc function, you can also use the chord function for drawing a solid circle.

draw.ellipse((150,65,190,105), fill = (0,255,0))

In essence, it's drawing an ellipse. The first parameter specifies the bounding rectangle of the chord, and fill = (0, 255, 0) indicates that the interior is filled with green color. If the bounding rectangle of the ellipse is a square, the ellipse becomes a circle.

  • Character.

The ImageFont module needs to be imported and instantiated:

Font1 = ImageFont.truetype("../Font/Font01.ttf",25)
Font2 = ImageFont.truetype("../Font/Font01.ttf",35)
Font3 = ImageFont.truetype("../Font/Font02.ttf",32)

You can use the fonts of Windows or other fonts which is in ttc format..
Note: Each character library contains different characters; If some characters cannot be displayed, it is recommended that you refer to the encoding set to be used. To draw English characters, you can directly use the fonts; for Chinese characters, you need to add a symbol u:

draw.text((40, 50), 'WaveShare', fill = (128,255,128),font=Font2)
text= u"微雪电子"
draw.text((74, 150),text, fill = "WHITE",font=Font3)

The first parameter is a 2-element tuple with (40, 50) as the left-top point. The font is set to Font2, and you can specify the font color with fill. You can directly use fill = "WHITE", as standard color values are already defined. Alternatively, you can use fill = (128, 255, 128), where the values in parentheses correspond to the RGB values for precise color control.
The second line displays "Waveshare" using Font3, with the font color set to white.

  • Read local pictures.
image = Image.open('../pic/LCD_1inch28.jpg')

The parameter is the image path.

  • Other functions.

Python's image library is very powerful, if you need to implement more, you can learn on the website http://effbot.org/imagingbook pil.

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FAQ

 Answer:

a) Check if SPI (Serial Peripheral Interface) is enabled.
b) Verify if the backlight pin has output. If there is no output, you can try leaving the BL (backlight) control cable unconnected.

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 Answer:

If running the wiringPi demo works normally, then subsequently running the Python or BCM2835 demo might result in the screen not refreshing properly. This is because the BCM2835 library is a library for the Raspberry Pi's CPU chip and its low level is directly operating registers. The wiringPi library and Python interact with device files in the Linux system, which can potentially cause issues with GPIO pins. Rebooting the Raspberry Pi can often provide a perfect solution.

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 Answer:

In C language, you can control rotation using the function Paint_SetRotate(Rotate). However, in C, the rotation angle can only be set to 0, 90, 180, or 270 degrees.

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 Answer:

For some Raspberry Pi systems, the 'image' library may not be available. You can run: 'sudo apt-get install python-imaging' to install the 'python-imaging' library.

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