digilent-xdc VS StickIt

I'm using the Nexys A7 constraint file provided by Digilent, which describes the main clock as follows: set_property -dict { PACKAGE_PIN E3 IOSTANDARD LVCMOS33 } [get_ports { CLK100MHZ }]; create_clock -add -name sys_clk_pin -period 10.00 -waveform {0 5} [get_ports {CLK100MHZ}];

Looked here: https://github.com/Digilent/digilent-xdc/blob/master/Cora-Z7-07S-Master.xdc This xdc will have all the constraints in it with the package pins. (This is for the 07S if you go to the main folder it also has the 10 if that's the FPGA you have (since the Cora offers 2 options). Look at this link for the reference manual. https://digilent.com/reference/programmable-logic/cora-z7/reference-manual?redirect=1 It will cover a lot about the Board. You should be able to use almost any GPIO pin as long as it is not used by something already (i e. Ethernet, LEDs etc )

Then you can look at the Hardware manual, and the docs for the UART PMod and then you can get the constraint for that line. page 23 gives you the FPGA mapping for each PMod port, so all you need to do is make that an external port, and then create a constraints file that maps that data line to the FPGA port, and sets the bank voltage. You can see a 'master' constraints file here: https://github.com/Digilent/digilent-xdc/blob/master/Zedboard-Master.xdc

looking at, for example, https://github.com/Digilent/digilent-xdc/blob/master/Nexys-Video-Master.xdc

There is one other neat trick called "Charlie-plexing" where you take advantage of high-Z pin states and the diode nature of the segments to conserve I/O: see https://github.com/xesscorp/StickIt/tree/master/modules/LedDigits