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//----------------------------------------------------------------------------
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// Copyright (C) 2001 Authors
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//
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// This source file may be used and distributed without restriction provided
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// that this copyright statement is not removed from the file and that any
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// derivative work contains the original copyright notice and the associated
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// disclaimer.
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//
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// This source file is free software; you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This source is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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// License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with this source; if not, write to the Free Software Foundation,
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// Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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//
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//----------------------------------------------------------------------------
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//
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olivier.gi |
// *File Name: omsp_watchdog.v
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olivier.gi |
//
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// *Module Description:
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// Watchdog Timer
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//
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// *Author(s):
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// - Olivier Girard, olgirard@gmail.com
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//
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//----------------------------------------------------------------------------
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olivier.gi |
// $Rev: 34 $
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// $LastChangedBy: olivier.girard $
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// $LastChangedDate: 2009-12-29 20:10:34 +0100 (Tue, 29 Dec 2009) $
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//----------------------------------------------------------------------------
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olivier.gi |
`include "timescale.v"
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`include "openMSP430_defines.v"
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olivier.gi |
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olivier.gi |
module omsp_watchdog (
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olivier.gi |
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// OUTPUTs
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nmi_evt, // NMI Event
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per_dout, // Peripheral data output
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wdtifg_set, // Set Watchdog-timer interrupt flag
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wdtpw_error, // Watchdog-timer password error
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wdttmsel, // Watchdog-timer mode select
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// INPUTs
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aclk_en, // ACLK enable
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dbg_freeze, // Freeze Watchdog counter
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mclk, // Main system clock
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nmi, // Non-maskable interrupt (asynchronous)
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nmie, // Non-maskable interrupt enable
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per_addr, // Peripheral address
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per_din, // Peripheral data input
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per_en, // Peripheral enable (high active)
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per_wen, // Peripheral write enable (high active)
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puc, // Main system reset
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smclk_en, // SMCLK enable
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wdtie // Watchdog timer interrupt enable
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);
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// OUTPUTs
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//=========
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output nmi_evt; // NMI Event
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output [15:0] per_dout; // Peripheral data output
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output wdtifg_set; // Set Watchdog-timer interrupt flag
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output wdtpw_error; // Watchdog-timer password error
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output wdttmsel; // Watchdog-timer mode select
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// INPUTs
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//=========
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input aclk_en; // ACLK enable
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input dbg_freeze; // Freeze Watchdog counter
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input mclk; // Main system clock
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input nmi; // Non-maskable interrupt (asynchronous)
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input nmie; // Non-maskable interrupt enable
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input [7:0] per_addr; // Peripheral address
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input [15:0] per_din; // Peripheral data input
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input per_en; // Peripheral enable (high active)
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input [1:0] per_wen; // Peripheral write enable (high active)
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input puc; // Main system reset
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input smclk_en; // SMCLK enable
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input wdtie; // Watchdog timer interrupt enable
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//=============================================================================
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// 1) PARAMETER DECLARATION
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//=============================================================================
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// Register addresses
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parameter WDTCTL = 9'h120;
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// Register one-hot decoder
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parameter WDTCTL_D = (512'h1 << WDTCTL);
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//============================================================================
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// 2) REGISTER DECODER
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//============================================================================
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// Register address decode
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reg [511:0] reg_dec;
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always @(per_addr)
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case ({per_addr,1'b0})
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WDTCTL : reg_dec = WDTCTL_D;
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default: reg_dec = {512{1'b0}};
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endcase
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// Read/Write probes
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wire reg_write = |per_wen & per_en;
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wire reg_read = ~|per_wen & per_en;
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// Read/Write vectors
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wire [511:0] reg_wr = reg_dec & {512{reg_write}};
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wire [511:0] reg_rd = reg_dec & {512{reg_read}};
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//============================================================================
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// 3) REGISTERS
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//============================================================================
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// WDTCTL Register
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//-----------------
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// WDTNMI & WDTSSEL are not implemented and therefore masked
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reg [7:0] wdtctl;
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wire wdtctl_wr = reg_wr[WDTCTL];
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always @ (posedge mclk or posedge puc)
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if (puc) wdtctl <= 8'h00;
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else if (wdtctl_wr) wdtctl <= per_din[7:0] & 8'hd7;
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wire wdtpw_error = wdtctl_wr & (per_din[15:8]!=8'h5a);
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wire wdttmsel = wdtctl[4];
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//============================================================================
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// 3) REGISTERS
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//============================================================================
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// Data output mux
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wire [15:0] wdtctl_rd = {8'h69, wdtctl} & {16{reg_rd[WDTCTL]}};
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wire [15:0] per_dout = wdtctl_rd;
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//=============================================================================
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// 4) NMI GENERATION
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//=============================================================================
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// Synchronization state
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reg [2:0] nmi_sync;
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always @ (posedge mclk or posedge puc)
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if (puc) nmi_sync <= 3'h0;
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else nmi_sync <= {nmi_sync[1:0], nmi};
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// Edge detection
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wire nmi_re = ~nmi_sync[2] & nmi_sync[0] & nmie;
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wire nmi_fe = nmi_sync[2] & ~nmi_sync[0] & nmie;
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// NMI event
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wire nmi_evt = wdtctl[6] ? nmi_fe : nmi_re;
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//=============================================================================
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// 5) WATCHDOG TIMER
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//=============================================================================
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// Watchdog clock source selection
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//---------------------------------
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wire clk_src_en = wdtctl[2] ? aclk_en : smclk_en;
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// Watchdog 16 bit counter
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//--------------------------
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reg [15:0] wdtcnt;
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wire wdtcnt_clr = (wdtctl_wr & per_din[3]) | wdtifg_set;
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always @ (posedge mclk or posedge puc)
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if (puc) wdtcnt <= 16'h0000;
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else if (wdtcnt_clr) wdtcnt <= 16'h0000;
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else if (~wdtctl[7] & clk_src_en & ~dbg_freeze) wdtcnt <= wdtcnt+16'h0001;
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// Interval selection mux
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//--------------------------
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reg wdtqn;
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always @(wdtctl or wdtcnt)
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case(wdtctl[1:0])
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2'b00 : wdtqn = wdtcnt[15];
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2'b01 : wdtqn = wdtcnt[13];
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2'b10 : wdtqn = wdtcnt[9];
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default: wdtqn = wdtcnt[6];
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endcase
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// Watchdog event detection
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//-----------------------------
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reg wdtqn_dly;
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always @ (posedge mclk or posedge puc)
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if (puc) wdtqn_dly <= 1'b0;
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else wdtqn_dly <= wdtqn;
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wire wdtifg_set = (~wdtqn_dly & wdtqn) | wdtpw_error;
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olivier.gi |
endmodule // omsp_watchdog
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`include "openMSP430_undefines.v"
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