PoroCYon

Hi, First some context: I'm trying to make a flashcart-like device (acting like a game cartridge for a console) using a Zybo. For this I'd need to interface with the processing system on one side (to manage which data goes in and out, and also to control a weird bizarro UART on the console which uses a PS/2 port but the protocol is totally different), and the pmod interfaces on the other side (to read out address lines and control signals, and to drive the data lines and UART). (The console in question here is the V-tech V.smile. Yes.) What would be the best way to create a custom IP in Vivado that accomplishes this? First create an AXI peripheral, then manually add the Pmod signals in the generated HDL code, and then group these into a Pmod interface in the "Ports and interfaces" UI? Or should I declare the signals in the constraints file, and then add them manually to the HDL wrapper etc. until it gets to my code? Or some other method? If the former, I have a few followup questions: why do these Pmod interfaces have 10 signals, while this page tells me there are only 8 data pins, and 2 for VCC and GND each. Are two of these signals unused? What if I use a pmod pin in only one direction, do I just leave the other unconnected, or should I do something else? What are the singals with suffix "_t" for, exactly? Thanks.