gpsdecoder.vhd

采用状态机完成GPS串口信息GPRMC数据的解析

--File Name: GPSdecoder
--Function : extract data,time,and status of GPS infomation
--Data     : 2008.3.29

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity GPSdecoder is
	port(GPSinfo	:in		std_logic_vector(7 downto 0);
		wr			:in		std_logic;
		ale			:out 	std_logic; 
		ABus		:out	std_logic_vector(7 downto 0);
		DBus		:out 	std_logic_vector(7 downto 0)
		);
end GPSdecoder;

architecture Behavioral of GPSdecoder is
--define address
constant 	month_add	:	std_logic_vector(7 downto 0):="11111000";	--f8
constant 	day_add		:	std_logic_vector(7 downto 0):="11111001";	--f9
constant 	year_add	:	std_logic_vector(7 downto 0):="11111010";	--fa

constant 	hour_add	:	std_logic_vector(7 downto 0):="11111011";	--fb
constant 	minu_add	:	std_logic_vector(7 downto 0):="11111100";	--fc
constant 	secd_add	:	std_logic_vector(7 downto 0):="11111101";	--fd

constant 	state_add	:	std_logic_vector(7 downto 0):="11111110";	--fe
constant    nullc		:	std_logic_vector(7 downto 0):="00000000";

--define signal
signal state : std_logic_vector(4 downto 0) := "00000";
signal comma : std_logic_vector(3 downto 0) := "0000";
signal temp1,temp2,temp3,sumt : std_logic_vector(7 downto 0);
signal num : std_logic_vector(7 downto 0);
--begin
begin


pro1:process(wr,num)
begin
	if rising_edge(wr) then
		num <= GPSinfo;
	end if;
end process;
	

pro2:process(wr)
--$GPRMC,0123456789
--24 47 50 52 4d 43 2c 30 31 32 33 34 35 36 37 38 39
begin
	if rising_edge(wr) then
		case state is
		when "00000" =>
			ale <= '0';
			if num="00100100" then	--$ 24
				state <= state + 1;
			else
				state <= "00000";
			end if;
			
		when "00001" =>
			--ale <= '0';
			if num="01000111" then	--G 47
				state <= state + 1;
			else
				state <= "00000";
			end if;
			
		when "00010" =>
			--ale <= '0';
			if num="01010000" then	--P 50
				state <= state + 1;
			else
				state <= "00000";
			end if;
			
		when "00011" =>
			--ale <= '0';
			if num="01010010" then	--R 52
				state <= state + 1;
			else
				state <= "00000";
			end if;
			
		when "00100" =>
			--ale <= '0';
			if num="01001101" then	--M 4d
				state <= state + 1;
			else 
				state <= "00000";
			end if;
			
		when "00101" =>
			--ale <= '0';
			if num="01000011" then	--C 43
				state <= state + 1;
			else
				state <= "00000";
			end if;
			
		when "00110" =>	--comma
			--ale <= '0';
			state <= state + 1;
			
		when "00111" =>	--hour high
			temp1 <= "0" & num(3 downto 0) & "000";	--*8
			temp2 <= "000" & num(3 downto 0) & "0";	--*2
			--ale <= '0';
			state <= state + 1;
			
		when "01000" =>	--hour low
			temp3 <= "0000" & num(3 downto 0);
			sumt <= temp1 + temp2;
			state <= state + 1;
			
		when "01001" =>	--minu high
			temp1 <= "0" & num(3 downto 0) & "000";	--*8
			temp2 <= "000" & num(3 downto 0) & "0";	--*2
			--output hour
			ABus <= hour_add;
			DBus <= sumt + temp3;
			ale <= '1';
			--
			state <= state + 1;
			
		when "01010" =>	--minu low
			temp3 <= "0000" & num(3 downto 0);
			sumt <= temp1 + temp2;
			ale <= '0';
			state <= state + 1;
			
		when "01011" =>	--second high
			temp1 <= "0" & num(3 downto 0) & "000";	--*8
			temp2 <= "000" & num(3 downto 0) & "0";	--*2
			--output minute
			ABus <= minu_add;
			DBus <= sumt + temp3;
			ale <= '1';
			--
			state <= state + 1;
			
		when "01100" =>	--second low
			temp3 <= "0000" & num(3 downto 0);
			sumt <= temp1 + temp2;
			ale <= '0';
			state <= state + 1;
			
		when "01101" =>	--.
			--output second
			ABus <= secd_add;
			DBus <= sumt +temp3;
			ale <= '1';
			state <= "11010";
			
		when "11010" =>	--minisecond
			ale <= '0';
			state <= state + 1;
			
		when "11011" =>
			state <= state +1;
			
		when "11100" =>
			state <= state + 1;
			
		when "11101" => --,
			state <= "01110";
			
		when "01110" =>	--status
			temp1 <= num;
			state <= state + 1;
			
		when "01111" => --comma
			comma <= "0011";
			--output status
			ABus <= state_add;
			DBus <= temp1;
			ale <= '1';
			--
			state <= state +1;
			
		when "10000" =>
			ale <= '0';
			if num="00101100" then	--comma
				comma <= comma + 1;
				state <= state +1;
			else
				state <= state;
			end if;
			
		when "10001" =>
			if comma="1001" then	--day high
				state <= state + 1;
				temp1 <= "0" & num(3 downto 0) & "000";	--*8
				temp2 <= "000" & num(3 downto 0) & "0";	--*2
			else
				state <= "10000";
			end if;
			
		when "10010" =>	--day low
			comma <= "0000";
			temp3 <= "0000" & num(3 downto 0);
			sumt <= temp1 + temp2;
			state <= state + 1;
			
		when "10011" =>	--month high
			temp1 <= "0" & num(3 downto 0) & "000";	--*8
			temp2 <= "000" & num(3 downto 0) & "0";	--*2
			--output day
			ABus <= day_add;
			DBus <= sumt + temp3;
			ale <= '1';
			--
			state <= state + 1;
			
		when "10100" => --month low
			temp3 <= "0000" & num(3 downto 0);
			sumt <= temp1 + temp2;
			ale <= '0';
			state <= state +1;
			
		when "10101" =>	--year high
			temp1 <= "0" & num(3 downto 0) & "000";	--*8
			temp2 <= "000" & num(3 downto 0) & "0";	--*2
			--output month
			ABus <= month_add;
			DBus <= sumt + temp3;
			ale <= '1';
			--
			state <= state + 1;
			
		when "10110" => --year low
			temp3 <= "0000" & num(3 downto 0);
			sumt <= temp1 + temp2;
			ale <= '0';
			state <= state + 1;
			
		when "10111" => --comma
			--output year
			ABus <= year_add;
			DBus <= sumt + temp3;
			ale <= '1';
			--
			state <= "00000";
							
		when others =>
			ale <= '0';
			state <= "00000";
			
		end case;
	end if;
	
end process;
end Behavioral;