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keyboardverilogfpgaxilinx-isespartan
Noah Mendoza
Noah Mendoza

Reputation: 837

Baysis2 Keyboard ports always high

I'm trying to create a password system with a baysis2 FPGA and verilog that verifies a password which is entered via keyboard. I need to make sure that my keyboard is working properly, as it seems to be a bit glitchy. I was told that the best way to make sure my keyboard is sending data to the board is by checking to see if ps2d and ps2c are high when I press a button, which makes sense. The problem is that in testing, the two LEDs I bound ps2d and ps2c to are ALWAYS LOGICAL HIGH even when the keyboard is disconnected! Is this some feature of verilog/Xilinx ISE or does my board have a bad port?

The following is my Verilog code.

module wtf(ps2d, ps2c, ps2dout, ps2cout);

    input wire ps2d, ps2c;
    output wire ps2dout, ps2cout;

    assign ps2dout = ps2d;
    assign ps2cout = ps2c;

endmodule

With the following constraint file 

NET "ps2c"    LOC = "B1"   | DRIVE = 2  | PULLUP ; 
NET "ps2d"    LOC = "C3"   | DRIVE = 2  | PULLUP ; 
NET "ps2cout" LOC = "G1" ;
NET "ps2dout" LOC = "P4" ;

Upvotes: 0

Views: 74

Answers (1)

alex.forencich
alex.forencich

Reputation: 1435

Well, the UCF file enables internal pull-ups on those pins, so reading those as high with nothing connected is exactly what it is supposed to do.

Upvotes: 1

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