You can install the touch driver for 3.5″touch screen on an existing system, but it just supports raspbian and ubuntu system.

Raspberry Pi must be connected to the Internet,and you can control it through ssh,vnc, Remote desktop or the other big HDMI display.

touchscreen

Driver Installation:
First, change the password of the root account and enable the root account::
sudo passwd root
sudo passwd –unlock root
su root

Step 1:Open the command terminal,Enter the following commands to download the 3.5″touch screen driver;
sudo git clone https://github.com/kedei/LCD_driver

Step 2:Change file permissions;
sudo chmod -R 777 LCD_driver

Step 3:Enter the folder;
cd LCD_driver

Step 4:Install the driver, RaspberryPi will auto reboot ;
./LCD35_show

You can use the following command to rotate the screen 

Rotate 90°  
su root
cd LCD_driver  
./LCD35_show 90

Rotate 180°  
su root  
cd LCD_driver  
./LCD35_show 180

Rotate 270°
su root
cd LCD_driver  
./LCD35_show 270

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