Retropie with 7'' Touch Screen

This guide is to be used after you have completed the Retropie with Raspberry Pi guide. 

While touch functionality will not work in the Retropie main menu, it will work on some of its emulators such as DraStic (for NDS emulation). 

Right out of the box, there are three parts to the kit. 
The 7-inch LCD touch screen

A micro-usb cable

A short HDMI cable

Before connecting the touch screen to the Raspberry Pi, get out a microSD card reader and connect it to your computer

Insert the microSD card into the microSD card readerand it should show up under 'Devices' (On MacOS) or as a drive (On Windows OS). 

Edit the config.txt file with a text editor.For the screen to display in landscape mode, add the following lines to the end of the config.txt file:

max_usb_current=1

hdmi_group=2

hdmi_mode=87

hdmi_cvt 800 480 60 6 0 0 0

hdmi_force_hotplug=1

hdmi_drive=2

Save the changes and remove it from the computer.

Next, turn the backlight of the screen on by flicking the switch. 

Connect HDMI Port of LCD to HDMI Port of Pi

Please insert the microSD card into the Raspberry Pi. Then connect a wired keyboard.

Next connect microUSB Port of LCD to USB Port of the Raspberry Pi.

Finally, power up the Raspberry Pi by connecting the Raspberry Pi with the power supply included in the kit.

The Retropie splash screen will display on the 7-in touchscreen.

Now, access the terminal in Retropie by hitting the F4 button.
First, we will need to install libinput with the following code:
sudo apt-get install xserver-xorg-input-libinput

Now create an xorg.conf.d folder with the following command.
sudo mkdir /etc/X11/xorg.conf.d

The next step is to copy the file 40-libinput-conf to the folder which we just created. So use the following command: sudo cp /usr/share/X11/xorg.conf.d/40-libinput.conf /etc/X11/xorg.conf.d/

We will make several modifications to the file '40-libinput.conf' So run the following command: sudo nano /etc/X11/xorg.conf.d/40-libinput.conf

Once the file has been opened, scroll all the way down

Make sure there is a line that states 'Identifier 'libinput touchscreen catchall' '

Add the line 'Option "CalibrationMatrix" "0 1 0 -1 0 1 0 0 1"

Save changes by hitting 'CTRL+X', then 'Y' and then 'Enter'.

Some experimental emulators such as DraStic will need to be installed.On the main menu, select 'Retropie' to view the settings menu where you will see Audio, Bluetooth, Configuration Editor etc.

Select 'Retropie Setup'

Select 'Manage packages'

Select 'Manage experimental packages'

Select 'drastic'

Select  'Install from binary'

Let the installation run to completion, this may take a few minutes.

Once a ROM has been added, the emulator will show up on the main menu.

Select the Nintendo DS emulator

Select the ROM of your choice

Press 'M'  to bring up the menu as shown

Select 'Change Options' and set up any changes as you'd like

Select 'Configure Controls' to manually set up the controls for games running on DraStic

Connect a game controller and remove the keyboard if desired

Use a finger on the screen and start playing.