• 4 floors
• AC
• DISP floor number
• Open/Close door after 3 clock cycles
• prioritize requests depending on moving direction
• asynch RESET

• call buttons on elevator panel
  • F1 F2 F3 F4
• up/down buttons on each floor
  • U1 U2 U3 U4
  • D1 D2 D3 D4
• floor sensors
  • S1 S2 S3 S4

If a call button is pressed, the elevator will store the request in a register till it reaches the floor. Requests will be cleared with the clr signal of register.

register regF(.in(F), .clr(clrF), .out(F_));

wire B1, B2, B3, B4, NB;
assign B1 = F1_ | U1_ | D1_;
assign B2 = F2_ | U2_ | D2_;
assign B3 = F3_ | U3_ | D3_;
assign B4 = F4_ | U4_ | D4_;
assign NB = ~(B1 | B2 | B3 | B4);

B1-B4 is activated if there is any request to the floor. NB is activated if there is no request at all.

• AC
  • 0: up
  • 1: down
  • 2: stop
• Open
  • 0: close
  • 1: open

always @(posedge CLK) begin
  if (Open == 1)
      counter <= counter + 1;
  else
      counter <= 0;
end

After the door is opened, the counter will start counting. When it reaches 3, the door will be closed.

wait(counter == 3);