master.v

   1 `include "master_rom.v"
   2 `include "i2c.v"
   3 `include "uart.v"
   4
   5 `ifdef SIM
   6  `define UART_DIVIDE 1
   7 `else
   8  `define UART_DIVIDE 1
   9  // s/192/3/ for 19200 baud uart
  10 `endif
  11
  12 module master(input CLKin, output [4:0] led, output uart_tx, input uart_rx, output reg ready_out = 1, input ready_in, output scl, output sda);
  13 //   wire clk;
  14 //   wire clk_tmp;
  15
  16    //pll pll (.clock_in(CLKin), .clock_out(clk));
  17
  18    reg [20:0] counter = 0;
  19
  20 `ifdef SIM
  21    wire clk = CLKin;
  22 `else
  23    reg            clk = 0;
  24
  25    always @ (posedge CLKin) begin
  26           if(counter == 5000) begin
  27                  counter <= 0;
  28                  clk <= 1 - clk;
  29           end
  30           else
  31                 counter <= counter + 1;
  32    end
  33 `endif
  34
  35    reg [3:0] program_counter = 0;
  36    wire [31:0] rom_output;
  37
  38    master_rom master_rom (.clk(clk), .addr(program_counter), .data(rom_output));
  39
  40    reg [7:0]   i2c_tx_byte;
  41    reg             i2c_transmit = 0;
  42    wire            i2c_is_transmitting;
  43
  44    i2c_write i2c (.clk(clk), .scl(scl), .sda(sda), .tx_byte(i2c_tx_byte), .transmit(i2c_transmit), .is_transmitting(i2c_is_transmitting));
  45
  46    reg [3:0]   i2c_init_step = 0;
  47
  48    always @ (posedge clk) begin
  49           if(i2c_is_transmitting || i2c_transmit)
  50                 i2c_transmit <= 0;
  51           else begin
  52                  if(i2c_init_step == 0) begin
  53                         i2c_tx_byte <= 8'h21; // turn on oscillator
  54                         i2c_transmit <= 1;
  55                         i2c_init_step <= 1;
  56                  end else if(i2c_init_step == 1) begin
  57                         i2c_tx_byte <= 8'h87; // display on, blink 0.5Hz
  58                         i2c_transmit <= 1;
  59                         i2c_init_step <= 2;
  60                  end else if(i2c_init_step == 2) begin
  61                         i2c_tx_byte <= 8'hEF; // max brightness
  62                         i2c_transmit <= 1;
  63                         i2c_init_step <= 3;
  64                  end
  65           end
  66    end
  67
  68
  69 `define STATE_SEND 0
  70 `define STATE_WAIT_PROPAGATE 1
  71 `define STATE_WAIT_NEWS 2
  72 `define STATE_PROPAGATE_NEWS 3
  73 `define STATE_WASTE_TIME 4
  74
  75    reg [5:0] state = `STATE_SEND;
  76    reg [5:0] uart_ptr = 0;
  77
  78    wire            received;
  79    wire [7:0]  rx_byte;
  80    reg             transmit = 0;
  81    reg  [7:0]  tx_byte = 0;
  82    wire            is_receiving;
  83    wire            is_transmitting;
  84
  85    // 19200 (actually 300) baud uart
  86    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));
  87
  88    reg [15:0]  waste_counter = 0;
  89
  90    reg [7:0]   saved_news [3:0];
  91
  92    assign led[4] = state != `STATE_WASTE_TIME;
  93    assign led[3:0] = i2c_init_step;
  94
  95    always @(posedge clk) begin
  96           case(state)
  97                 `STATE_SEND: begin
  98                    if(transmit) begin
  99                           transmit <= 0;
 100                    end else if(uart_ptr == 4) begin
 101                           program_counter <= program_counter + 1;
 102                           uart_ptr <= 0;
 103                           if(rom_output[26:24] == 6) // `OP_ROUTE
 104                                 state <= `STATE_WAIT_NEWS;
 105                           else
 106                                 state <= `STATE_WAIT_PROPAGATE;
 107                    end else if(!is_transmitting && ready_in) begin
 108                           tx_byte <= rom_output[uart_ptr * 8 +: 8];
 109                           transmit <= 1;
 110                           uart_ptr <= uart_ptr + 1;
 111                    end
 112                 end
 113
 114                 `STATE_WAIT_PROPAGATE: begin
 115                    if(received) begin
 116                           state <= `STATE_WASTE_TIME;
 117                    end
 118                 end
 119
 120                 `STATE_WASTE_TIME: begin
 121                    if(waste_counter == 100) begin
 122                           waste_counter <= 0;
 123                           state <= `STATE_SEND;
 124                    end else
 125                          waste_counter <= waste_counter + 1;
 126                 end
 127
 128                 `STATE_WAIT_NEWS: begin
 129                    /** On a route instruction, we:
 130                            - receive the instruction back
 131                            - receive the news
 132                            - propagate the news
 133                            - go to `STATE_WASTE_TIME
 134                         */
 135                    if(uart_ptr == 8) begin
 136                           state <= `STATE_PROPAGATE_NEWS;
 137                           uart_ptr <= 0;
 138                    end else if(received) begin
 139                           if(uart_ptr[2]) /* uart_ptr >= 4 */
 140                                 saved_news[uart_ptr[1:0]] <= rx_byte;
 141                           uart_ptr <= uart_ptr + 1;
 142                    end
 143                 end // case: `STATE_WAIT_NEWS
 144
 145                 `STATE_PROPAGATE_NEWS: begin
 146                    if(uart_ptr == 4) begin
 147                           state <= `STATE_WASTE_TIME;
 148                           uart_ptr <= 0;
 149                    end else if(!is_transmitting && ready_in) begin
 150                           tx_byte <= saved_news[uart_ptr];
 151                           transmit <= 1;
 152                           uart_ptr <= uart_ptr + 1;
 153                    end
 154                 end
 155           endcase
 156    end
 157
 158 endmodule