master.v

   1 `include "master_rom.v"
   2
   3 `ifdef SIM
   4  `define UART_DIVIDE 1
   5 `else
   6  `define UART_DIVIDE 1
   7  // s/192/3/ for 19200 baud uart
   8 `endif
   9
  10 module master(input CLKin, output [4:0] led, output uart_tx, input uart_rx, output reg ready_out = 1, input ready_in);
  11    wire clk;
  12    wire clk_tmp;
  13
  14    //pll pll (.clock_in(CLKin), .clock_out(clk));
  15
  16    reg [20:0] counter = 0;
  17
  18    reg            clk = 0;
  19
  20    always @ (posedge CLKin) begin
  21           if(counter == 5000) begin
  22                  counter <= 0;
  23                  clk <= 1 - clk;
  24           end
  25           else
  26                 counter <= counter + 1;
  27    end
  28
  29    reg [3:0] program_counter = 0;
  30    wire [31:0] rom_output;
  31
  32    master_rom master_rom (.clk(clk), .addr(program_counter), .data(rom_output));
  33
  34
  35 `define STATE_SEND 0
  36 `define STATE_WAIT_PROPAGATE 1
  37 `define STATE_WAIT_NEWS 2
  38 `define STATE_PROPAGATE_NEWS 3
  39 `define STATE_WASTE_TIME 4
  40
  41    reg [5:0] state = `STATE_SEND;
  42    reg [5:0] uart_ptr = 0;
  43
  44    wire            received;
  45    wire [7:0]  rx_byte;
  46    reg             transmit = 0;
  47    reg  [7:0]  tx_byte = 0;
  48    wire            is_receiving;
  49    wire            is_transmitting;
  50
  51    // 19200 (actually 300) baud uart
  52    uart #(.CLOCK_DIVIDE(`UART_DIVIDE)) uart (.clk(clk), .rx(uart_rx), .tx(uart_tx), .received(received), .transmit(transmit), .tx_byte(tx_byte), .rx_byte(rx_byte), .is_receiving(is_receiving), .is_transmitting(is_transmitting));
  53
  54    reg [15:0]  waste_counter = 0;
  55
  56    reg [7:0]   saved_news [3:0];
  57
  58    assign led[4] = state != `STATE_WASTE_TIME;
  59    assign led[3:0] = 0;
  60
  61    always @(posedge clk) begin
  62           case(state)
  63                 `STATE_SEND: begin
  64                    if(transmit) begin
  65                           transmit <= 0;
  66                    end else if(uart_ptr == 4) begin
  67                           program_counter <= program_counter + 1;
  68                           uart_ptr <= 0;
  69                           if(rom_output[26:24] == 6) // `OP_ROUTE
  70                                 state <= `STATE_WAIT_NEWS;
  71                           else
  72                                 state <= `STATE_WAIT_PROPAGATE;
  73                    end else if(!is_transmitting && ready_in) begin
  74                           tx_byte <= rom_output[uart_ptr * 8 +: 8];
  75                           transmit <= 1;
  76                           uart_ptr <= uart_ptr + 1;
  77                    end
  78                 end
  79
  80                 `STATE_WAIT_PROPAGATE: begin
  81                    if(received) begin
  82                           state <= `STATE_WASTE_TIME;
  83                    end
  84                 end
  85
  86                 `STATE_WASTE_TIME: begin
  87                    if(waste_counter == 100) begin
  88                           waste_counter <= 0;
  89                           state <= `STATE_SEND;
  90                    end else
  91                          waste_counter <= waste_counter + 1;
  92                 end
  93
  94                 `STATE_WAIT_NEWS: begin
  95                    /** On a route instruction, we:
  96                            - receive the instruction back
  97                            - receive the news
  98                            - propagate the news
  99                            - go back to `STATE_SEND
 100                         */
 101                    if(uart_ptr == 8) begin
 102                           state <= `STATE_PROPAGATE_NEWS;
 103                           uart_ptr <= 0;
 104                    end else if(received) begin
 105                           if(uart_ptr[2]) /* uart_ptr >= 4 */
 106                                 saved_news[uart_ptr[1:0]] <= rx_byte;
 107                           uart_ptr <= uart_ptr + 1;
 108                    end
 109                 end // case: `STATE_WAIT_NEWS
 110
 111                 `STATE_PROPAGATE_NEWS: begin
 112                    if(uart_ptr == 4) begin
 113                           state <= `STATE_WASTE_TIME;
 114                           uart_ptr <= 0;
 115                    end else if(!is_transmitting && ready_in) begin
 116                           tx_byte <= saved_news[uart_ptr];
 117                           transmit <= 1;
 118                           uart_ptr <= uart_ptr + 1;
 119                    end
 120                 end
 121           endcase
 122    end
 123
 124 endmodule