From 0df4b801a34697f2058b4a7b95e08d2a0576c9db Mon Sep 17 00:00:00 2001
From: Ben Hilburn <ben.hilburn@ettus.com>
Date: Thu, 10 Oct 2013 10:17:27 -0700
Subject: Squashed B200 FPGA Source. Code from Josh Blum, Ian Buckley, and Matt
 Ettus.

---
 fpga/usrp3/lib/control/cvita_uart.v | 164 ++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 fpga/usrp3/lib/control/cvita_uart.v

(limited to 'fpga/usrp3/lib/control/cvita_uart.v')

diff --git a/fpga/usrp3/lib/control/cvita_uart.v b/fpga/usrp3/lib/control/cvita_uart.v
new file mode 100644
index 000000000..cbb272fc2
--- /dev/null
+++ b/fpga/usrp3/lib/control/cvita_uart.v
@@ -0,0 +1,164 @@
+
+//
+// Copyright 2013 Ettus Research LLC
+//
+
+
+//create a compressed vita based uart data interface
+
+module cvita_uart
+#(
+    parameter SIZE = 0
+)
+(
+    //clocking interface
+    input clk, input rst,
+
+    //uart interface
+    input rxd, output txd,
+
+    //chdr fifo input
+    input [63:0] i_tdata,
+    input i_tlast,
+    input i_tvalid,
+    output i_tready,
+
+    //chdr fifo output
+    output [63:0] o_tdata,
+    output o_tlast,
+    output o_tvalid,
+    input o_tready
+);
+
+    reg [31:0] sid;
+
+    //baud clock divider
+    reg [15:0] clkdiv;
+
+    //hold rx in disable until a tx event
+    reg rxd_enable;
+
+    //==================================================================
+    //== RXD capture and packet generation interface
+    //==================================================================
+    wire [7:0] rx_char;
+    wire fifo_empty;
+    wire fifo_read;
+    reg [11:0] seqnum;
+    wire pgen_trigger;
+    wire pgen_done;
+
+    //rx uart capture
+    simple_uart_rx #(.SIZE(SIZE)) simple_uart_rx
+    (
+        .clk(clk), .rst(rst),
+        .fifo_out(rx_char), .fifo_read(fifo_read), .fifo_level(), .fifo_empty(fifo_empty),
+        .clkdiv(clkdiv), .rx(rxd)
+    );
+
+    //packet generation - holds rx character
+    context_packet_gen context_packet_gen
+    (
+        .clk(clk), .reset(rst), .clear(1'b0),
+        .trigger(pgen_trigger),
+        .seqnum(seqnum),
+        .sid({sid[15:0], sid[31:16]}),
+        .body({56'b0, rx_char}),
+        .vita_time(64'b0),
+
+        .done(pgen_done),
+        .o_tdata(o_tdata), .o_tlast(o_tlast), .o_tvalid(o_tvalid), .o_tready(o_tready)
+    );
+
+    //state machine to manage pgen and rx uart
+    reg [1:0] rxd_state;
+    localparam RXD_STATE_RECV_CHAR = 0;
+    localparam RXD_STATE_PGEN_TRIG = 1;
+    localparam RXD_STATE_WAIT_DONE = 2;
+    localparam RXD_STATE_READ_FIFO = 3;
+
+    always @(posedge clk) begin
+        if (rst) begin
+            seqnum <= 12'b0;
+            rxd_state <= RXD_STATE_RECV_CHAR;
+        end
+        else case (rxd_state)
+
+        RXD_STATE_RECV_CHAR: begin
+            if (!fifo_empty && rxd_enable) rxd_state <= RXD_STATE_PGEN_TRIG;
+        end
+
+        RXD_STATE_PGEN_TRIG: begin
+            rxd_state <= RXD_STATE_WAIT_DONE;
+        end
+
+        RXD_STATE_WAIT_DONE: begin
+            if (pgen_done) rxd_state <= RXD_STATE_READ_FIFO;
+        end
+
+        RXD_STATE_READ_FIFO: begin
+            rxd_state <= RXD_STATE_RECV_CHAR;
+            seqnum <= seqnum + 1'b1;
+        end
+
+        endcase //rxd_state
+    end
+
+    assign fifo_read = (rxd_state == RXD_STATE_READ_FIFO) || (!rxd_enable);
+    assign pgen_trigger = (rxd_state == RXD_STATE_PGEN_TRIG);
+
+    //==================================================================
+    //== TXD generation and packet control interface
+    //==================================================================
+    wire [7:0] tx_char;
+    wire fifo_write;
+    wire fifo_full;
+
+    simple_uart_tx #(.SIZE(SIZE)) simple_uart_tx
+    (
+        .clk(clk), .rst(rst),
+        .fifo_in(tx_char), .fifo_write(fifo_write), .fifo_level(), .fifo_full(fifo_full),
+        .clkdiv(clkdiv), .baudclk(), .tx(txd)
+    );
+
+    //state machine to manage control and tx uart
+    reg [1:0] txd_state;
+    localparam TXD_STATE_RECV_CHDR = 0;
+    localparam TXD_STATE_RECV_TIME = 1;
+    localparam TXD_STATE_RECV_BODY = 2;
+    localparam TXD_STATE_DROP_FIFO = 3;
+
+    always @(posedge clk) begin
+        if (rst) begin;
+            txd_state <= TXD_STATE_RECV_CHDR;
+            rxd_enable <= 1'b0;
+        end
+        if (i_tvalid && i_tready) case (txd_state)
+
+        TXD_STATE_RECV_CHDR: begin
+            txd_state <= (i_tdata[61])? TXD_STATE_RECV_TIME : TXD_STATE_RECV_BODY;
+            sid <= i_tdata[31:0];
+        end
+
+        TXD_STATE_RECV_TIME: begin
+            txd_state <= TXD_STATE_RECV_BODY;
+        end
+
+        TXD_STATE_RECV_BODY: begin
+            txd_state <= (i_tlast)? TXD_STATE_RECV_CHDR : TXD_STATE_DROP_FIFO;
+            clkdiv <= i_tdata[47:32];
+            rxd_enable <= 1'b1;
+        end
+
+        TXD_STATE_DROP_FIFO: begin
+            if (i_tlast) txd_state <= TXD_STATE_RECV_CHDR;
+        end
+
+        endcase //txd_state
+    end
+
+    assign tx_char = i_tdata[7:0];
+    assign fifo_write = (txd_state == TXD_STATE_RECV_BODY) && i_tvalid && i_tready;
+    assign i_tready = !fifo_full;
+
+endmodule // cvita_uart
-- 
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