X-Git-Url: http://git.rot13.org/?p=BML_sump2;a=blobdiff_plain;f=sump2%2Fsource%2Fmesa_ascii2nibble.v;fp=sump2%2Fsource%2Fmesa_ascii2nibble.v;h=7f8aa6c04a1ecfc54d402adf4af38d1e81376cd7;hp=0000000000000000000000000000000000000000;hb=b6ac52f611f53e96447a6bee178d418f14623985;hpb=bbafe3d7b73ed7bf085686eb333ea10a968bd40b

diff --git a/sump2/source/mesa_ascii2nibble.v b/sump2/source/mesa_ascii2nibble.v
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+/* ****************************************************************************
+-- Source file: mesa_ascii2nibble.v                
+-- Date:        October 4, 2015
+-- Author:      khubbard
+-- Description: Convert an ASCII character to a binary nibble.
+-- Language:    Verilog-2001 and VHDL-1993
+-- Simulation:  Mentor-Modelsim 
+-- Synthesis:   Lattice     
+-- License:     This project is licensed with the CERN Open Hardware Licence
+--              v1.2.  You may redistribute and modify this project under the
+--              terms of the CERN OHL v.1.2. (http://ohwr.org/cernohl).
+--              This project is distributed WITHOUT ANY EXPRESS OR IMPLIED
+--              WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY
+--              AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN OHL
+--              v.1.2 for applicable Conditions.
+--
+-- Revision History:
+-- Ver#  When      Who      What
+-- ----  --------  -------- ---------------------------------------------------
+-- 0.1   10.04.15  khubbard Creation
+-- ***************************************************************************/
+`default_nettype none // Strictly enforce all nets to be declared
+
+module mesa_ascii2nibble
+(
+  input  wire         clk,
+  input  wire         rx_char_en,
+  input  wire [7:0]   rx_char_d,
+  output reg          rx_nib_en,
+  output reg  [3:0]   rx_nib_d
+);// module mesa_ascii2nibble
+
+  reg  [4:0]   rx_nib_bin; // MSB is Valid Char Flag for "0"-"F"
+
+
+//-----------------------------------------------------------------------------
+// When UART receives an ASCII char, see if it is 0-9,a-f,A-F else toss   
+//-----------------------------------------------------------------------------
+always @ ( posedge clk ) begin : proc_rx  
+  rx_nib_d   <= rx_nib_bin[3:0];
+  rx_nib_en  <= rx_char_en & rx_nib_bin[4];
+end
+
+
+//-----------------------------------------------------------------------------
+// Convert ASCII to binary nibbles. Toss and ignore all other received chars
+// 0x30 = "0"
+// 0x39 = "9"
+// 0x41 = "A"
+// 0x46 = "F"
+// 0x61 = "a"
+// 0x66 = "f"
+//-----------------------------------------------------------------------------
+always @ ( * ) begin : proc_lut
+ begin
+  case( rx_char_d[7:0] )
+    8'h30   : rx_nib_bin[4:0] <= 5'h10;// 0
+    8'h31   : rx_nib_bin[4:0] <= 5'h11;
+    8'h32   : rx_nib_bin[4:0] <= 5'h12;
+    8'h33   : rx_nib_bin[4:0] <= 5'h13;
+    8'h34   : rx_nib_bin[4:0] <= 5'h14;
+    8'h35   : rx_nib_bin[4:0] <= 5'h15;
+    8'h36   : rx_nib_bin[4:0] <= 5'h16;
+    8'h37   : rx_nib_bin[4:0] <= 5'h17;
+    8'h38   : rx_nib_bin[4:0] <= 5'h18;
+    8'h39   : rx_nib_bin[4:0] <= 5'h19;// 9
+
+    8'h41   : rx_nib_bin[4:0] <= 5'h1A;// A
+    8'h42   : rx_nib_bin[4:0] <= 5'h1B;
+    8'h43   : rx_nib_bin[4:0] <= 5'h1C;
+    8'h44   : rx_nib_bin[4:0] <= 5'h1D;
+    8'h45   : rx_nib_bin[4:0] <= 5'h1E;
+    8'h46   : rx_nib_bin[4:0] <= 5'h1F;// F
+
+    8'h61   : rx_nib_bin[4:0] <= 5'h1A;// a
+    8'h62   : rx_nib_bin[4:0] <= 5'h1B;
+    8'h63   : rx_nib_bin[4:0] <= 5'h1C;
+    8'h64   : rx_nib_bin[4:0] <= 5'h1D;
+    8'h65   : rx_nib_bin[4:0] <= 5'h1E;
+    8'h66   : rx_nib_bin[4:0] <= 5'h1F;// f
+
+    default : rx_nib_bin[4:0] <= 5'h0F;
+  endcase
+ end
+end // proc_lut
+
+
+endmodule // mesa_ascii2nibble