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// Automatic transmit/receive switching of control pins to daughterboards
// Store everything in registers for now, but could use a RAM for more
// complex state machines in the future
module atr_controller16
(input clk_i, input rst_i,
input [5:0] adr_i, input [1:0] sel_i, input [15:0] dat_i, output reg [15:0] dat_o,
input we_i, input stb_i, input cyc_i, output reg ack_o,
input run_rx, input run_tx,
output [31:0] ctrl_lines);
reg [3:0] state;
reg [31:0] atr_ram [0:15]; // DP distributed RAM
wire [3:0] sel_int = { (sel_i[1] & adr_i[1]), (sel_i[0] & adr_i[1]),
(sel_i[1] & ~adr_i[1]), (sel_i[0] & ~adr_i[1]) };
// WB Interface
always @(posedge clk_i)
if(we_i & stb_i & cyc_i)
begin
if(sel_int[3])
atr_ram[adr_i[5:2]][31:24] <= dat_i[15:8];
if(sel_int[2])
atr_ram[adr_i[5:2]][23:16] <= dat_i[7:0];
if(sel_int[1])
atr_ram[adr_i[5:2]][15:8] <= dat_i[15:8];
if(sel_int[0])
atr_ram[adr_i[5:2]][7:0] <= dat_i[7:0];
end // if (we_i & stb_i & cyc_i)
always @(posedge clk_i)
dat_o <= adr_i[1] ? atr_ram[adr_i[5:2]][31:16] : atr_ram[adr_i[5:2]][15:0];
always @(posedge clk_i)
ack_o <= stb_i & cyc_i & ~ack_o;
// Control side of DP RAM
assign ctrl_lines = atr_ram[state];
// Put a more complex state machine with time delays and multiple states here
// if daughterboard requires more complex sequencing
localparam ATR_IDLE = 4'd0;
localparam ATR_TX = 4'd1;
localparam ATR_RX = 4'd2;
localparam ATR_FULL_DUPLEX = 4'd3;
always @(posedge clk_i)
if(rst_i)
state <= ATR_IDLE;
else
case ({run_rx,run_tx})
2'b00 : state <= ATR_IDLE;
2'b01 : state <= ATR_TX;
2'b10 : state <= ATR_RX;
2'b11 : state <= ATR_FULL_DUPLEX;
endcase // case({run_rx,run_tx})
endmodule // atr_controller16
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