src/pc_communication.vhd

   1 library ieee;
   2 use ieee.std_logic_1164.all;
   3 use ieee.numeric_std.all;
   4 use work.gen_pkg.all;
   5
   6 entity pc_communication is
   7         port (
   8                 sys_clk : in std_logic;
   9                 sys_res_n : in std_logic;
  10
  11                 --button
  12                 btn_a : in std_logic;
  13
  14                 --uart_tx
  15                 tx_data : out std_logic_vector(7 downto 0);
  16                 tx_new : out std_logic;
  17                 tx_done : in std_logic;
  18
  19                 --uart_rx
  20                 rx_data : in std_logic_vector(7 downto 0); --not really required
  21                 rx_new : in std_logic;
  22
  23                 -- History
  24                 d_zeile : out hzeile;
  25                 d_spalte : out hspalte;
  26                 d_get :  out std_logic;
  27                 d_done : in std_logic;
  28                 d_char : in hbyte
  29         );
  30 end entity pc_communication;
  31
  32 architecture beh of pc_communication is
  33         signal push_history, push_history_next : std_logic;
  34
  35         signal spalte, spalte_next : hspalte;
  36         signal zeile , zeile_next : hzeile;
  37         signal spalte_up, spalte_up_next : std_logic;
  38
  39         signal char, char_next : hbyte;
  40         signal char_en : std_logic;
  41         type STATE_PC is (IDLE, FETCH, FORWARD, DONE);
  42         signal state, state_next : STATE_PC ;
  43
  44 begin
  45
  46         sync: process (sys_clk, sys_res_n)
  47         begin
  48                 if sys_res_n = '0' then
  49                         state <= IDLE;
  50                         push_history <= '0';
  51                         spalte <= "0000000";
  52                         zeile <= "0000000";
  53                 elsif rising_edge(sys_clk) then
  54                         push_history <= push_history_next;
  55                         spalte <= spalte_next;
  56                         zeile <= zeile_next;
  57                         state <= state_next;
  58                         if (char_en = '1') then
  59                                 state <= state_next;
  60                         end if;
  61                 end if;
  62         end process sync;
  63
  64         process (spalte_up)
  65         variable spalte_tmp, zeile_tmp : integer;
  66         begin
  67                 if (spalte_up = '1') then
  68                         if (spalte > X"45") then
  69                                 spalte_next <= "0000000";
  70                                 zeile_tmp := to_integer(unsigned(zeile));
  71                                 zeile_tmp := zeile_tmp + 1;
  72                                 zeile_next <= hbyte(to_unsigned(zeile_tmp,8));
  73                         else
  74                                 spalte_tmp := to_integer(unsigned(spalte));
  75                                 spalte_tmp := spalte_tmp + 1;
  76                                 spalte_next <= hbyte(to_unsigned(spalte_tmp,8));
  77                                 zeile_next <= zeile;
  78                         end if;
  79                         spalte_up <= '0';
  80                 end if;
  81         end process;
  82
  83         async_push_history : process (rx_new, rx_data, btn_a)
  84         begin
  85                 if rx_new = '1' then
  86                         if rx_data = X"41" then
  87                                 push_history_next <= '1';
  88                         else
  89                                 push_history_next <= '0';
  90                         end if;
  91                 elsif btn_a = '1' then
  92                                 push_history_next <= '1';
  93                 else
  94                         push_history_next <= '0';
  95                 end if;
  96         end process async_push_history;
  97
  98         output_pc : process (zeile, spalte)
  99         begin
 100                 case state is
 101                         when IDLE =>
 102                                 spalte_next <= "0000000";
 103                                 zeile_next <= "0000000";
 104                         when FETCH =>
 105                                 d_zeile <= zeile;
 106                                 d_spalte <= spalte;
 107                                 d_get <= '1';
 108                                 char_en <= '1';
 109                                 -- wait for timer overflow
 110                                 -- increment counter
 111                         when FORWARD =>
 112                                 char_en <= '0';
 113                                 tx_data <= char;
 114                                 tx_new <= '1';
 115                         when DONE =>
 116                                 null;
 117                                 -- be there for a single cycle and then
 118                 end case;
 119         end process output_pc;
 120
 121         next_state_pc : process (rx_new, btn_a)
 122         begin
 123                 case state is
 124                         when IDLE =>
 125                                 if rx_new= '1' or btn_a = '1' then
 126                                         state_next <= FETCH;
 127                                         char <= d_char; --latch
 128                                 end if;
 129                         when FETCH =>
 130                                 if (d_done = '1') then
 131                                         state_next <= FORWARD;
 132                                 end if;
 133                         when FORWARD =>
 134                                 if (tx_done = '1') then
 135                                         state_next <= FETCH;
 136                                 end if;
 137                         when DONE =>
 138                                 -- be there for a single cycle and then
 139                                 state_next <= IDLE;
 140                 end case;
 141         end process next_state_pc;
 142
 143 end architecture beh;