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ball.sv.bak
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//-------------------------------------------------------------------------
// Ball.sv --
// Viral Mehta --
// Spring 2005 --
// --
// Modified by Stephen Kempf 03-01-2006 --
// 03-12-2007 --
// Translated by Joe Meng 07-07-2013 --
// Fall 2014 Distribution --
// --
// For use with ECE 298 Lab 7 --
// UIUC ECE Department --
//-------------------------------------------------------------------------
module ball ( input Reset, frame_clk,
input [7:0] keycode,
output [9:0] BallX, BallY, BallS );
logic [9:0] Ball_X_Pos, Ball_X_Motion, Ball_Y_Pos, Ball_Y_Motion, Ball_Size;
parameter [9:0] Ball_X_Center=320; // Center position on the X axis
parameter [9:0] Ball_Y_Center=240; // Center position on the Y axis
parameter [9:0] Ball_X_Min=0; // Leftmost point on the X axis
parameter [9:0] Ball_X_Max=639; // Rightmost point on the X axis
parameter [9:0] Ball_Y_Min=0; // Topmost point on the Y axis
parameter [9:0] Ball_Y_Max=479; // Bottommost point on the Y axis
parameter [9:0] Ball_X_Step=1; // Step size on the X axis
parameter [9:0] Ball_Y_Step=1; // Step size on the Y axis
assign Ball_Size = 4; // assigns the value 4 as a 10-digit binary number, ie "0000000100"
always_ff @ (posedge Reset or posedge frame_clk )
begin: Move_Ball
if (Reset) // Asynchronous Reset
begin
Ball_Y_Motion <= 10'd0; //Ball_Y_Step;
Ball_X_Motion <= 10'd0; //Ball_X_Step;
Ball_Y_Pos <= Ball_Y_Center;
Ball_X_Pos <= Ball_X_Center;
end
else
begin
if ( (Ball_Y_Pos + Ball_Size) >= Ball_Y_Max ) // Ball is at the bottom edge, BOUNCE!
Ball_Y_Motion <= (~ (Ball_Y_Step) + 1'b1); // 2's complement.
else if ( (Ball_Y_Pos - Ball_Size) <= Ball_Y_Min ) // Ball is at the top edge, BOUNCE!
Ball_Y_Motion <= Ball_Y_Step;
else if ( (Ball_X_Pos + Ball_Size) >= Ball_X_Max ) // Ball is at the Right edge, BOUNCE!
Ball_X_Motion <= (~ (Ball_X_Step) + 1'b1); // 2's complement.
else if ( (Ball_X_Pos - Ball_Size) <= Ball_X_Min ) // Ball is at the Left edge, BOUNCE!
Ball_X_Motion <= Ball_X_Step;
else
Ball_Y_Motion <= Ball_Y_Motion; // Ball is somewhere in the middle, don't bounce, just keep moving
case (keycode)
8'h04 : begin
Ball_X_Motion <= -1;//A
Ball_Y_Motion<= 0;
end
8'h07 : begin
Ball_X_Motion <= 1;//D
Ball_Y_Motion <= 0;
end
8'h16 : begin
Ball_Y_Motion <= 1;//S
Ball_X_Motion <= 0;
end
8'h1A : begin
Ball_Y_Motion <= -1;//W
Ball_X_Motion <= 0;
end
default: ;
endcase
Ball_Y_Pos <= (Ball_Y_Pos + Ball_Y_Motion); // Update ball position
Ball_X_Pos <= (Ball_X_Pos + Ball_X_Motion);
/**************************************************************************************
ATTENTION! Please answer the following quesiton in your lab report! Points will be allocated for the answers!
Hidden Question #2/2:
Note that Ball_Y_Motion in the above statement may have been changed at the same clock edge
that is causing the assignment of Ball_Y_pos. Will the new value of Ball_Y_Motion be used,
or the old? How will this impact behavior of the ball during a bounce, and how might that
interact with a response to a keypress? Can you fix it? Give an answer in your Post-Lab.
**************************************************************************************/
end
end
assign BallX = Ball_X_Pos;
assign BallY = Ball_Y_Pos;
assign BallS = Ball_Size;
endmodule