1 files changed, 79 insertions, 0 deletions
diff --git a/fpga/usrp2/control_lib/simple_uart.v b/fpga/usrp2/control_lib/simple_uart.v
new file mode 100644
index 000000000..f44a719f4
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+++ b/fpga/usrp2/control_lib/simple_uart.v
@@ -0,0 +1,79 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+
+module simple_uart
+  #(parameter TXDEPTH = 1,
+    parameter RXDEPTH = 1,
+    parameter CLKDIV_DEFAULT = 16'd0)
+   (input clk_i, input rst_i,
+    input we_i, input stb_i, input cyc_i, output reg ack_o,
+    input [2:0] adr_i, input [31:0] dat_i, output reg [31:0] dat_o,
+    output rx_int_o, output tx_int_o, output tx_o, input rx_i, output baud_o);
+   
+   // Register Map
+   localparam SUART_CLKDIV = 0;
+   localparam SUART_TXLEVEL = 1;
+   localparam SUART_RXLEVEL = 2;
+   localparam SUART_TXCHAR = 3;
+   localparam SUART_RXCHAR = 4;
+   
+   wire       wb_acc = cyc_i & stb_i;            // WISHBONE access
+   wire       wb_wr  = wb_acc & we_i;            // WISHBONE write access
+   
+   reg [15:0] clkdiv;
+   wire [7:0] rx_char;
+   wire       tx_fifo_full, rx_fifo_empty;   
+   wire [7:0] tx_fifo_level, rx_fifo_level;
+   
+   always @(posedge clk_i)
+     if (rst_i)
+       ack_o <= 1'b0;
+     else
+       ack_o <= wb_acc & ~ack_o;
+   
+   always @(posedge clk_i)
+     if (rst_i)
+       clkdiv <= CLKDIV_DEFAULT;
+     else if (wb_wr)
+       case(adr_i)
+	 SUART_CLKDIV : clkdiv <= dat_i[15:0];
+       endcase // case(adr_i)
+   
+   always @(posedge clk_i)
+     case (adr_i)
+       SUART_TXLEVEL : dat_o <= tx_fifo_level;
+       SUART_RXLEVEL : dat_o <= rx_fifo_level;
+       SUART_RXCHAR : dat_o <= rx_char;
+     endcase // case(adr_i)
+   
+   simple_uart_tx #(.DEPTH(TXDEPTH)) simple_uart_tx
+     (.clk(clk_i),.rst(rst_i),
+      .fifo_in(dat_i[7:0]),.fifo_write(ack_o && wb_wr && (adr_i == SUART_TXCHAR)),
+      .fifo_level(tx_fifo_level),.fifo_full(tx_fifo_full),
+      .clkdiv(clkdiv),.baudclk(baud_o),.tx(tx_o));
+   
+   simple_uart_rx #(.DEPTH(RXDEPTH)) simple_uart_rx
+     (.clk(clk_i),.rst(rst_i),
+      .fifo_out(rx_char),.fifo_read(ack_o && ~wb_wr && (adr_i == SUART_RXCHAR)),
+      .fifo_level(rx_fifo_level),.fifo_empty(rx_fifo_empty),
+      .clkdiv(clkdiv),.rx(rx_i));
+   
+   assign     tx_int_o = ~tx_fifo_full;
+   assign     rx_int_o = ~rx_fifo_empty;
+   
+endmodule // simple_uart