1 //----------------------------------------------------------------------------
2 // Copyright (C) 2001 Authors
4 // This source file may be used and distributed without restriction provided
5 // that this copyright statement is not removed from the file and that any
6 // derivative work contains the original copyright notice and the associated
9 // This source file is free software; you can redistribute it and/or modify
10 // it under the terms of the GNU Lesser General Public License as published
11 // by the Free Software Foundation; either version 2.1 of the License, or
12 // (at your option) any later version.
14 // This source is distributed in the hope that it will be useful, but WITHOUT
15 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 // FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17 // License for more details.
19 // You should have received a copy of the GNU Lesser General Public License
20 // along with this source; if not, write to the Free Software Foundation,
21 // Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 //----------------------------------------------------------------------------
25 // *File Name: omsp_mem_backbone.v
27 // *Module Description:
28 // Memory interface backbone (decoder + arbiter)
31 // - Olivier Girard, olgirard@gmail.com
33 //----------------------------------------------------------------------------
35 // $LastChangedBy: olivier.girard $
36 // $LastChangedDate: 2009-12-29 20:10:34 +0100 (Tue, 29 Dec 2009) $
37 //----------------------------------------------------------------------------
38 `include "timescale.v"
39 `include "openMSP430_defines.v"
41 module omsp_mem_backbone (
44 dbg_mem_din, // Debug unit Memory data input
45 dmem_addr, // Data Memory address
46 dmem_cen, // Data Memory chip enable (low active)
47 dmem_din, // Data Memory data input
48 dmem_wen, // Data Memory write enable (low active)
49 eu_mdb_in, // Execution Unit Memory data bus input
50 fe_mdb_in, // Frontend Memory data bus input
51 fe_pmem_wait, // Frontend wait for Instruction fetch
52 per_addr, // Peripheral address
53 per_din, // Peripheral data input
54 per_wen, // Peripheral write enable (high active)
55 per_en, // Peripheral enable (high active)
56 pmem_addr, // Program Memory address
57 pmem_cen, // Program Memory chip enable (low active)
58 pmem_din, // Program Memory data input (optional)
59 pmem_wen, // Program Memory write enable (low active) (optional)
62 dbg_halt_st, // Halt/Run status from CPU
63 dbg_mem_addr, // Debug address for rd/wr access
64 dbg_mem_dout, // Debug unit data output
65 dbg_mem_en, // Debug unit memory enable
66 dbg_mem_wr, // Debug unit memory write
67 dmem_dout, // Data Memory data output
68 eu_mab, // Execution Unit Memory address bus
69 eu_mb_en, // Execution Unit Memory bus enable
70 eu_mb_wr, // Execution Unit Memory bus write transfer
71 eu_mdb_out, // Execution Unit Memory data bus output
72 fe_mab, // Frontend Memory address bus
73 fe_mb_en, // Frontend Memory bus enable
74 mclk, // Main system clock
75 per_dout, // Peripheral data output
76 pmem_dout, // Program Memory data output
77 puc // Main system reset
82 output [15:0] dbg_mem_din; // Debug unit Memory data input
83 output [`DMEM_MSB:0] dmem_addr; // Data Memory address
84 output dmem_cen; // Data Memory chip enable (low active)
85 output [15:0] dmem_din; // Data Memory data input
86 output [1:0] dmem_wen; // Data Memory write enable (low active)
87 output [15:0] eu_mdb_in; // Execution Unit Memory data bus input
88 output [15:0] fe_mdb_in; // Frontend Memory data bus input
89 output fe_pmem_wait; // Frontend wait for Instruction fetch
90 output [7:0] per_addr; // Peripheral address
91 output [15:0] per_din; // Peripheral data input
92 output [1:0] per_wen; // Peripheral write enable (high active)
93 output per_en; // Peripheral enable (high active)
94 output [`PMEM_MSB:0] pmem_addr; // Program Memory address
95 output pmem_cen; // Program Memory chip enable (low active)
96 output [15:0] pmem_din; // Program Memory data input (optional)
97 output [1:0] pmem_wen; // Program Memory write enable (low active) (optional)
101 input dbg_halt_st; // Halt/Run status from CPU
102 input [15:0] dbg_mem_addr; // Debug address for rd/wr access
103 input [15:0] dbg_mem_dout; // Debug unit data output
104 input dbg_mem_en; // Debug unit memory enable
105 input [1:0] dbg_mem_wr; // Debug unit memory write
106 input [15:0] dmem_dout; // Data Memory data output
107 input [14:0] eu_mab; // Execution Unit Memory address bus
108 input eu_mb_en; // Execution Unit Memory bus enable
109 input [1:0] eu_mb_wr; // Execution Unit Memory bus write transfer
110 input [15:0] eu_mdb_out; // Execution Unit Memory data bus output
111 input [14:0] fe_mab; // Frontend Memory address bus
112 input fe_mb_en; // Frontend Memory bus enable
113 input mclk; // Main system clock
114 input [15:0] per_dout; // Peripheral data output
115 input [15:0] pmem_dout; // Program Memory data output
116 input puc; // Main system reset
119 //=============================================================================
121 //=============================================================================
126 // Execution unit access
127 wire eu_dmem_cen = ~(eu_mb_en & (eu_mab>=(`DMEM_BASE>>1)) &
128 (eu_mab<((`DMEM_BASE+`DMEM_SIZE)>>1)));
129 wire [15:0] eu_dmem_addr = eu_mab-(`DMEM_BASE>>1);
131 // Debug interface access
132 wire dbg_dmem_cen = ~(dbg_mem_en & (dbg_mem_addr[15:1]>=(`DMEM_BASE>>1)) &
133 (dbg_mem_addr[15:1]<((`DMEM_BASE+`DMEM_SIZE)>>1)));
134 wire [15:0] dbg_dmem_addr = dbg_mem_addr[15:1]-(`DMEM_BASE>>1);
138 wire [`DMEM_MSB:0] dmem_addr = ~dbg_dmem_cen ? dbg_dmem_addr[`DMEM_MSB:0] : eu_dmem_addr[`DMEM_MSB:0];
139 wire dmem_cen = dbg_dmem_cen & eu_dmem_cen;
140 wire [1:0] dmem_wen = ~(dbg_mem_wr | eu_mb_wr);
141 wire [15:0] dmem_din = ~dbg_dmem_cen ? dbg_mem_dout : eu_mdb_out;
146 parameter PMEM_OFFSET = (16'hFFFF-`PMEM_SIZE+1);
148 // Execution unit access (only read access are accepted)
149 wire eu_pmem_cen = ~(eu_mb_en & ~|eu_mb_wr & (eu_mab>=(PMEM_OFFSET>>1)));
150 wire [15:0] eu_pmem_addr = eu_mab-(PMEM_OFFSET>>1);
153 wire fe_pmem_cen = ~(fe_mb_en & (fe_mab>=(PMEM_OFFSET>>1)));
154 wire [15:0] fe_pmem_addr = fe_mab-(PMEM_OFFSET>>1);
156 // Debug interface access
157 wire dbg_pmem_cen = ~(dbg_mem_en & (dbg_mem_addr[15:1]>=(PMEM_OFFSET>>1)));
158 wire [15:0] dbg_pmem_addr = dbg_mem_addr[15:1]-(PMEM_OFFSET>>1);
161 // ROM Interface (Execution unit has priority)
162 wire [`PMEM_MSB:0] pmem_addr = ~dbg_pmem_cen ? dbg_pmem_addr[`PMEM_MSB:0] :
163 ~eu_pmem_cen ? eu_pmem_addr[`PMEM_MSB:0] : fe_pmem_addr[`PMEM_MSB:0];
164 wire pmem_cen = fe_pmem_cen & eu_pmem_cen & dbg_pmem_cen;
165 wire [1:0] pmem_wen = ~dbg_mem_wr;
166 wire [15:0] pmem_din = dbg_mem_dout;
168 wire fe_pmem_wait = (~fe_pmem_cen & ~eu_pmem_cen);
172 //--------------------
173 wire dbg_per_en = dbg_mem_en & (dbg_mem_addr[15:9]==7'h00);
174 wire eu_per_en = eu_mb_en & (eu_mab[14:8]==7'h00);
176 wire [7:0] per_addr = dbg_mem_en ? dbg_mem_addr[8:1] : eu_mab[7:0];
177 wire [15:0] per_din = dbg_mem_en ? dbg_mem_dout : eu_mdb_out;
178 wire [1:0] per_wen = dbg_mem_en ? dbg_mem_wr : eu_mb_wr;
179 wire per_en = dbg_mem_en ? dbg_per_en : eu_per_en;
181 reg [15:0] per_dout_val;
182 always @ (posedge mclk or posedge puc)
183 if (puc) per_dout_val <= 16'h0000;
184 else per_dout_val <= per_dout;
188 //---------------------------------
189 // Whenever the frontend doesn't access the ROM, backup the data
191 // Detect whenever the data should be backuped and restored
193 always @(posedge mclk or posedge puc)
194 if (puc) fe_pmem_cen_dly <= 1'b0;
195 else fe_pmem_cen_dly <= fe_pmem_cen;
197 wire fe_pmem_save = ( fe_pmem_cen & ~fe_pmem_cen_dly) & ~dbg_halt_st;
198 wire fe_pmem_restore = (~fe_pmem_cen & fe_pmem_cen_dly) | dbg_halt_st;
200 reg [15:0] pmem_dout_bckup;
201 always @(posedge mclk or posedge puc)
202 if (puc) pmem_dout_bckup <= 16'h0000;
203 else if (fe_pmem_save) pmem_dout_bckup <= pmem_dout;
205 // Mux between the ROM data and the backup
206 reg pmem_dout_bckup_sel;
207 always @(posedge mclk or posedge puc)
208 if (puc) pmem_dout_bckup_sel <= 1'b0;
209 else if (fe_pmem_save) pmem_dout_bckup_sel <= 1'b1;
210 else if (fe_pmem_restore) pmem_dout_bckup_sel <= 1'b0;
212 assign fe_mdb_in = pmem_dout_bckup_sel ? pmem_dout_bckup : pmem_dout;
215 // Execution-Unit data Mux
216 //---------------------------------
218 // Select between peripherals, RAM and ROM
219 reg [1:0] eu_mdb_in_sel;
220 always @(posedge mclk or posedge puc)
221 if (puc) eu_mdb_in_sel <= 2'b00;
222 else eu_mdb_in_sel <= {~eu_pmem_cen, per_en};
225 assign eu_mdb_in = eu_mdb_in_sel[1] ? pmem_dout :
226 eu_mdb_in_sel[0] ? per_dout_val : dmem_dout;
228 // Debug interface data Mux
229 //---------------------------------
231 // Select between peripherals, RAM and ROM
232 reg [1:0] dbg_mem_din_sel;
233 always @(posedge mclk or posedge puc)
234 if (puc) dbg_mem_din_sel <= 2'b00;
235 else dbg_mem_din_sel <= {~dbg_pmem_cen, dbg_per_en};
238 assign dbg_mem_din = dbg_mem_din_sel[1] ? pmem_dout :
239 dbg_mem_din_sel[0] ? per_dout_val : dmem_dout;
242 endmodule // omsp_mem_backbone
244 `include "openMSP430_undefines.v"