4x4 keyboard matrix not generating unique keycodes

Question

I have a 4x4 keybord matrix fsm scanner but it generates only high keycode setting all last 4 bits to 1 and second and fourth digits to high. Is there anything wrong in my code here?

module keyboardScanner (input clk, input [3:0] col,output reg [3:0] row, output reg [7:0] keyCode);
reg [1:0]state=2'b00;
reg [1:0]nextState=2'b00;
//state register
always@(posedge clk) begin
 state <= nextState;
end
//output CL
always@(posedge clk) begin
 case (state)
 2'b00: row <= 4'b0001;
 2'b01: row <= 4'b0010;
 2'b10: row <= 4'b0100;
 2'b11: row <= 4'b1000;
 default: row <= 4'b0001;
 endcase
 if (col != 4'b0000) begin
 keyCode <= {row[0],row[1],row[2],row[3], col[0],col[1],col[2],col[3]};
 end
end
//next state CL
always @(posedge clk) begin
 case (state)
 2'b00: nextState <= 2'b01;
 2'b01: nextState <= 2'b10;
 2'b10: nextState <= 2'b11;
 2'b11: nextState <= 2'b00;
 default: nextState <= 2'b00;
 endcase
end
endmodule

Please help me. It used to work 2 days ago, but now... :/

• Paebbels: Do you have any documentation or schematic for us?
• Paebbels: Are you using the Digilent keypad as a Pmod device? There is the possibiliy of floating inputs ... you should enable pullups in the FPGA's IOBs.
• Paebbels: I found the original Digilent example code for the 4×4 keypad. You have to drive column and read row! This prevents you from having floating inputs.
• Paebbels: Ok, I have found a board picture, but I can't find any schematic. Have a look at the Digilent PmodKYPD and its schematic. As you can see the columns have no pullup or pulldown resistor, whereas the rows have. That means columns have to be driven and rows to read. Please compare it to your beti board schematic.
• anon: There is no resistor in either of them in beti board so its quite different. No matter if you choose row or col as driver it will be the same. Thanks for information, it will be helpful knowledge :)

Answer 1

I found the answer. It was a clock halt problem. Clock was grounded and it destroyed the thing. Now it works fine!