Parallel Port Communications.txt

The parallel port itself is initialized in CSpaceInvadersBCI.cpp, but see ParallelPort/ParallelPort.cpp for the actual code. It uses a library/dll that is not my own code, though im sure you can find it on google should you need it.

Now, as for the messaging themselves. There are four different triggers, consisting of an unsigned integer. They are:

0, 64, 128 and 192

Now, as for the communication with the PP itself. In my code, they are mostly found in the GameScreen.cpp function update();

This function considers the different states the game is in, and switches to a new one when a timer reaches some point. They call for functions to draw a row/column as a flash or to restore it to its original state. After that, the ppTag() function is called, with a corresponding trigger. Below you'll find the cases (as they were in the original BI-code) and the trigger sent.

1) Flash an alien. Send Trigger 1.

2) Unflash an alien. Send Trigger 0.

3) When a repetition of the flashes (so start to flash all rows and columns) is started, the following sequence is send: Trigger 2, Trigger 0, with a full second between triggers (assuming this is for pausing.

4) When the game supposedly ends, the Sequence Trigger 3, Trigger 0 is send, with a 100 ms pause between the triggers (which I'm assuming is for processing)