added nexys_video files and docs for picosoc_demo

xc7/picosoc_demo/Makefile

@@ -16,6 +16,9 @@ else ifeq ($(TARGET),arty_100)
 else ifeq ($(TARGET),nexys4ddr)
   SOURCES += ${current_dir}/nexys4ddr.v
   PCF := ${current_dir}/nexys4ddr.pcf
+else ifeq ($(TARGET),nexys_video)
+  SOURCES += ${current_dir}/nexysvideo.v
+  PCF := ${current_dir}/nexysvideo.pcf
 else
   SOURCES += ${current_dir}/basys3.v
   PCF := ${current_dir}/basys3.pcf

xc7/picosoc_demo/README.rst

@@ -26,6 +26,11 @@ This example features a picorv32 soft CPU and a SoC based on it. To build the pi
 
    TARGET="basys3" make -C picosoc_demo
 
+.. code-block:: bash
+   :name: example-picosoc-nexys_video-group
+
+   TARGET="nexys_video" make -C picosoc_demo
+
 At completion, the bitstreams are located in the build directory:
 
 .. code-block:: bash

xc7/picosoc_demo/nexysvideo.pcf

@@ -0,0 +1,26 @@
+# 100 MHz CLK
+set_io clk R4
+
+# UART
+set_io rx V18
+set_io tx AA19
+
+# LEDs
+set_io led[0] T14
+set_io led[1] T15
+set_io led[2] T16
+set_io led[3] U16
+set_io led[4] V15
+set_io led[5] W16
+set_io led[6] W15
+set_io led[7] Y13
+
+# SWs 
+set_io sw[0] E22
+set_io sw[1] F21
+set_io sw[2] G21
+set_io sw[3] G22
+set_io sw[4] H17
+set_io sw[5] J16
+set_io sw[6] K13
+set_io sw[7] M17

xc7/picosoc_demo/nexysvideo.v

@@ -0,0 +1,86 @@
+/*
+ *  PicoSoC - A simple example SoC using PicoRV32
+ *
+ *  Copyright (C) 2017  Clifford Wolf <clifford@clifford.at>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+module top (
+	input clk,
+
+	output tx,
+	input rx,
+
+    input [7:0] sw,
+	output [7:0] led,
+);
+
+	wire clk_bufg;
+	BUFG bufg (.I(clk), .O(clk_bufg));
+
+	reg [5:0] reset_cnt = 0;
+	wire resetn = &reset_cnt;
+
+	always @(posedge clk_bufg) begin
+		reset_cnt <= reset_cnt + !resetn;
+	end
+
+	wire        iomem_valid;
+	reg         iomem_ready;
+	wire [3:0]  iomem_wstrb;
+	wire [31:0] iomem_addr;
+	wire [31:0] iomem_wdata;
+	reg  [31:0] iomem_rdata;
+
+	reg [31:0] gpio;
+
+	assign led = gpio[7:0];
+
+	always @(posedge clk_bufg) begin
+		if (!resetn) begin
+			gpio <= 0;
+		end else begin
+			iomem_ready <= 0;
+			if (iomem_valid && !iomem_ready && iomem_addr[31:24] == 8'h 03) begin
+				iomem_ready <= 1;
+				iomem_rdata <= {2{sw, gpio[7:0]}};
+				if (iomem_wstrb[0]) gpio[7:0] <= iomem_wdata[7:0];
+				if (iomem_wstrb[1]) gpio[15:8] <= iomem_wdata[15:8];
+				if (iomem_wstrb[2]) gpio[23:16] <= iomem_wdata[23:16];
+				if (iomem_wstrb[3]) gpio[31:24] <= iomem_wdata[31:24];
+			end
+		end
+	end
+
+	picosoc_noflash soc (
+		.clk(clk_bufg),
+		.resetn(resetn),
+
+		.ser_tx(tx),
+		.ser_rx(rx),
+
+		.irq_5(1'b0),
+		.irq_6(1'b0),
+		.irq_7(1'b0),
+
+		.iomem_valid(iomem_valid),
+		.iomem_ready(iomem_ready),
+		.iomem_wstrb(iomem_wstrb),
+		.iomem_addr(iomem_addr),
+		.iomem_wdata(iomem_wdata),
+		.iomem_rdata(iomem_rdata)
+	);
+
+endmodule