requesthandler.vhd

< FPGA数字电子系统设计与开发实例导航> 一书的代码

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--
-- File        : e:\Courses\ComputerHardwareInterface\USB_IF_DESIGN\USB_IF\src\RequestHandler.vhd
-- Create Time : Sun Apr 18 22:13:51 2004
-- Title       : RequestHandler
-- Design      : USB Interface IP Core
-- Author      : Lou Xinghua ([e-mail])
-- Company     : Department of Engineering Physics in Tsinghua Unversity, Beijing, China
-- Version     : 1.0
--
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--
-- Description : This module works each time when the whole packet is received. It will
-- analyze the packet data and deal with the data.
--
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--{{ Section below this comment is automatically maintained
--   and may be overwritten
--{entity {RequestHandler} architecture {RequestHandler}}

library IEEE;
use IEEE.STD_LOGIC_1164.all;
use WORK.USB_PACKAGE.all;
use WORK.PDIUSBD12_PACKAGE.all;



entity RequestHandler is
	port(		   
		reset_n : in STD_LOGIC;		
		clk : in STD_LOGIC;  
		recv_n : in STD_LOGIC;
		req_type : in STD_LOGIC_VECTOR(7 downto 0);  
		cmd : out STD_LOGIC_VECTOR(7 downto 0);
		exec_n : out STD_LOGIC
	);
end RequestHandler;

--}} End of automatically maintained section

architecture RequestHandler of RequestHandler is	 

-- Internal Signals

-- State Machine
signal rh_state: REQUEST_HANDLER_STATE := RH_IDLE;

signal address_set: STD_LOGIC := '0';
begin

	-- enter your statements here --
	 
	-- main process 
	main_process:
	process( reset_n, clk )
	begin
		if reset_n = '0' then
			-- reset output signals
			cmd <= X"00";
			exec_n <= '1';	
			address_set <= '0';
			-- reset state machine
			rh_state <= RH_IDLE;
		elsif falling_edge(clk) then
			case rh_state is
			when RH_IDLE =>
				if recv_n = '0' then
					case req_type is
					when REQUEST_GET_DESCRIPTOR => 
						-- get descriptor request
						-- send different command according to device address 
						if address_set = '0' then
							cmd <= RH_SEND_DESCRIPTOR_1ST;
						else	
							cmd <= RH_SEND_DESCRIPTOR;
						end if;
						exec_n <= '0';
					when REQUEST_GET_STATUS =>
						-- get status request
						cmd <= RH_SEND_STATUS;
						exec_n <= '0';
					when REQUEST_SET_ADDRESS =>	 							  
						-- set address request
						address_set <= '1';
						cmd <= RH_SET_ADDRESS;
						exec_n <= '0';
					when REQUEST_SET_FEATURE =>
						-- set feature
						cmd <= RH_SET_FEATURE;
						exec_n <= '0';
					when REQUEST_CLEAR_FEATURE =>
						-- clear feature
						cmd <= RH_CLEAR_FEATURE;
						exec_n <= '0';
					when REQUEST_SET_CONFIGURATION | REQUEST_SET_DESCRIPTOR =>
						-- set configuration request
						cmd <= RH_SET_CONFIGURATION;
						exec_n <= '0';
					when REQUEST_GET_CONFIGURATION =>
						-- get configuration request
						cmd <= RH_SEND_CONFIGURATION;
						exec_n <= '0';
					when REQUEST_SET_INTERFACE =>
						-- set interface request
						cmd <= RH_SET_INTERFACE;
						exec_n <= '0';
					when others =>
						NULL;
					end case;
				else
					exec_n <= '1';				
					cmd <= RH_INVALID_COMMAND;
				end if;
			when others =>
				NULL;
			end case;
		end if;
	end process;
	
end RequestHandler;