https://blackmesalabs.wordpress.com/2016/10/24/sump2-96-msps-logic-analyzer-for-22/

[BML_sump2] / sump2 / source / mesa_ascii2nibble.v

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+/* ****************************************************************************\r
+-- Source file: mesa_ascii2nibble.v                \r
+-- Date:        October 4, 2015\r
+-- Author:      khubbard\r
+-- Description: Convert an ASCII character to a binary nibble.\r
+-- Language:    Verilog-2001 and VHDL-1993\r
+-- Simulation:  Mentor-Modelsim \r
+-- Synthesis:   Lattice     \r
+-- License:     This project is licensed with the CERN Open Hardware Licence\r
+--              v1.2.  You may redistribute and modify this project under the\r
+--              terms of the CERN OHL v.1.2. (http://ohwr.org/cernohl).\r
+--              This project is distributed WITHOUT ANY EXPRESS OR IMPLIED\r
+--              WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY\r
+--              AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN OHL\r
+--              v.1.2 for applicable Conditions.\r
+--\r
+-- Revision History:\r
+-- Ver#  When      Who      What\r
+-- ----  --------  -------- ---------------------------------------------------\r
+-- 0.1   10.04.15  khubbard Creation\r
+-- ***************************************************************************/\r
+`default_nettype none // Strictly enforce all nets to be declared\r
+\r
+module mesa_ascii2nibble\r
+(\r
+  input  wire         clk,\r
+  input  wire         rx_char_en,\r
+  input  wire [7:0]   rx_char_d,\r
+  output reg          rx_nib_en,\r
+  output reg  [3:0]   rx_nib_d\r
+);// module mesa_ascii2nibble\r
+\r
+  reg  [4:0]   rx_nib_bin; // MSB is Valid Char Flag for "0"-"F"\r
+\r
+\r
+//-----------------------------------------------------------------------------\r
+// When UART receives an ASCII char, see if it is 0-9,a-f,A-F else toss   \r
+//-----------------------------------------------------------------------------\r
+always @ ( posedge clk ) begin : proc_rx  \r
+  rx_nib_d   <= rx_nib_bin[3:0];\r
+  rx_nib_en  <= rx_char_en & rx_nib_bin[4];\r
+end\r
+\r
+\r
+//-----------------------------------------------------------------------------\r
+// Convert ASCII to binary nibbles. Toss and ignore all other received chars\r
+// 0x30 = "0"\r
+// 0x39 = "9"\r
+// 0x41 = "A"\r
+// 0x46 = "F"\r
+// 0x61 = "a"\r
+// 0x66 = "f"\r
+//-----------------------------------------------------------------------------\r
+always @ ( * ) begin : proc_lut\r
+ begin\r
+  case( rx_char_d[7:0] )\r
+    8'h30   : rx_nib_bin[4:0] <= 5'h10;// 0\r
+    8'h31   : rx_nib_bin[4:0] <= 5'h11;\r
+    8'h32   : rx_nib_bin[4:0] <= 5'h12;\r
+    8'h33   : rx_nib_bin[4:0] <= 5'h13;\r
+    8'h34   : rx_nib_bin[4:0] <= 5'h14;\r
+    8'h35   : rx_nib_bin[4:0] <= 5'h15;\r
+    8'h36   : rx_nib_bin[4:0] <= 5'h16;\r
+    8'h37   : rx_nib_bin[4:0] <= 5'h17;\r
+    8'h38   : rx_nib_bin[4:0] <= 5'h18;\r
+    8'h39   : rx_nib_bin[4:0] <= 5'h19;// 9\r
+\r
+    8'h41   : rx_nib_bin[4:0] <= 5'h1A;// A\r
+    8'h42   : rx_nib_bin[4:0] <= 5'h1B;\r
+    8'h43   : rx_nib_bin[4:0] <= 5'h1C;\r
+    8'h44   : rx_nib_bin[4:0] <= 5'h1D;\r
+    8'h45   : rx_nib_bin[4:0] <= 5'h1E;\r
+    8'h46   : rx_nib_bin[4:0] <= 5'h1F;// F\r
+\r
+    8'h61   : rx_nib_bin[4:0] <= 5'h1A;// a\r
+    8'h62   : rx_nib_bin[4:0] <= 5'h1B;\r
+    8'h63   : rx_nib_bin[4:0] <= 5'h1C;\r
+    8'h64   : rx_nib_bin[4:0] <= 5'h1D;\r
+    8'h65   : rx_nib_bin[4:0] <= 5'h1E;\r
+    8'h66   : rx_nib_bin[4:0] <= 5'h1F;// f\r
+\r
+    default : rx_nib_bin[4:0] <= 5'h0F;\r
+  endcase\r
+ end\r
+end // proc_lut\r
+\r
+\r
+endmodule // mesa_ascii2nibble\r