Marlin, at its core, is handed g-code from somewhere and executes that g-code. You will find the reference for the particular flavor of g-code run my Marlin here. The only question is how you want to send that g-code to Marlin, and Jeff’s list gives you an idea of how many there could be. Each method has its strengths and weaknesses. In order to get an overview, you might look at these two references:
- Software Workflow
- The graphic in this topic
There is one interesting twist with the particular setup you are building. The display has two modes. In touch mode, the display runs its own firmware and delivers g-code in a very similar way to an external computer. In Marlin mode (enabled by holding down the knob for three seconds) the display is being painted directly my Marlin. These two modes used different cabling. That is why there are three cables connecting the display to the control board.
Does the computer provide any control of the machine?
Most g-code senders provides some control of the machine…movement, homing and the like. They do it by sending g-code. Repetier-Host is the software documented by V1, and it has an interface for moving around and homing. Anything that Repetier-Host is doing to control Marlin is something you can do by manually sending g-code commands. Repetier-Host has an interface you can manually type in g-code commands and send them to Marlin. Repetier-Host also has a few buttons you can customize with g-code scripts.