By IOBUF dio bidirectional data to be input into the separation into the FPGA and di_d do_o obtained from FPGA. IOBUF control bit I input port T of FPGA enable high data, low output O is enabled.
IOBUF#(
.DRIVE(12), // Specify the output drivestrength
.IOSTANDARD("DEFAULT"), //Specify the I/O standard
.SLEW("SLOW") // Specify theoutput slew rate
) IOBUF_inst (
.O (di_d[dq_o] ), // Buffer output to fpga
.IO (dio[dq_o] ), // Buffer inout port (connect directly to top-level port)
.I (do_o[dq_o]), // Buffer input from fpga
.T (dir_o[dq_o/8 ]) // 3-state enableinput, high=input, low=output
);
