• Open the Raspberry Pi terminal and enter the following command to enter the configuration interface:
  

sudo raspi-config

• Select Interface Options -> SPI -> Yes to enable the SPI interface

• Continue to enter the config interface:
  

sudo raspi-config

• Select Interface Options -> I2C -> Yes to enable the I2C interface

• Restart Raspberry Pi
  

sudo reboot

• Check /boot/config.txt, you can see "dtparam=i2c_arm=on" and "dtparam=spi=on" are written
  

more  /boot/config.txt

• To ensure that SPI is not occupied, it is recommended that other driver overlays be temporarily turned off. You can use ls /dev/spi* to check the SPI occupancy. The terminal output /dev/spidev0.0 and /dev/spidev0.1 indicates that the SPI situation is normal

ls /dev/spi* 

Install libraries files

• Install libraries

sudo apt-get update
sudo apt-get install python3-pip
sudo apt-get install python3-pil
sudo apt-get install python3-numpy
sudo apt-get install python3-spidev

Demo operations

• Download the demo

cd
wget https://files.waveshare.com/wiki/3.5inch%20Capacitive%20Touch%20LCD/3.5inch_Capacitive_Touch_LCD_Demo_Pi.zip

• Install decompression environment (optional, skip this step if you have used the command to unzip)

sudo apt-get install unzip

• Enter the file location, and execute the command to unzip
  

unzip 3.5inch_Capacitive_Touch_LCD_Demo_Pi.zip -d ./3.5inch_Capacitive_Touch_LCD

• Enter Python file folder

cd 3.5inch_Capacitive_Touch_LCD/Python

• Run the example demo will display 3 images on the screen, and it will then enter the drawing function upon completion

python 3.5inch_Capacitive_Touch_LCD.py 

Install libraries files

• Install libraries

git clone https://github.com/WiringPi/WiringPi
cd WiringPi
./build
gpio -v

• Run gpio -v and version 70 will appear. If it does not appear, there is an installation error
• Download the demo file
• Enter the file directory, and run the demo

Demo operations

• Download the demo

cd
wget https://files.waveshare.com/wiki/3.5inch%20Capacitive%20Touch%20LCD/3.5inch_Capacitive_Touch_LCD_Demo_Pi.zip

• Install decompression environment (optional, skip this step if you have used the command to unzip)

sudo apt-get install unzip

• Enter the file location, and execute the command to unzip
  

unzip 3.5inch_Capacitive_Touch_LCD_Demo_Pi.zip -d ./3.5inch_Capacitive_Touch_LCD

• Enter C file folder

cd 3.5inch_Capacitive_Touch_LCD/C

• Clean compilation files and compile again

sudo make clean
sudo make -j

• Successfully compiled, run the example demo to perform RGB refresh on the screen, and it will then enter the drawing function upon completion

sudo ./main

Preparation

1. Install Thonny (Thonny installation package)
2. Press the "BOOTSEL" key on the Raspberry Pi Pico, and release it after powering
3. A new disk will appear on your computer, extract the (Raspberry Pi Pico firmware) and copy the firmware (suffix uf2) to that disk (the disk will automatically disappear if the copy is successful)
4. Open Thonny, click on "Python x.x.x" at the bottom right, and select "Configure interpreter"
5. Select "Interpreter" in the pop-up window -> select "MicroPython (Raspberry Pi Pico)" as the interpreter -> select "Auto-detect port" as the port
6. Click on "Stop", and the Shell window will show "MicroPython v1.20.0-50-g786013d46 on 2023-05-04; Raspberry Pi Pico with RP2040 Type "help()" for more information. " It means the connection is successful

• The following is the procedure for steps 4 and 5:
  

• The successful connection is shown below:
  

Demo

• Download the Demo

• Unzip the demo and open Thonny

• Open the demo, the path is: 3.5inch_Capacitive_Touch_LCD_Demo_Pico/Python/3.5inch_Capacitive_Touch_LCD.py

• Run the demo to achieve the drawing board function on the screen

• If you want to run the demo automatically at power-on, change the file name to main.py