--- /dev/null
+//----------------------------------------------------------------------------
+// Copyright (C) 2001 Authors
+//
+// This source file may be used and distributed without restriction provided
+// that this copyright statement is not removed from the file and that any
+// derivative work contains the original copyright notice and the associated
+// disclaimer.
+//
+// This source file is free software; you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This source is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+// License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this source; if not, write to the Free Software Foundation,
+// Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+//
+//----------------------------------------------------------------------------
+//
+// *File Name: omsp_watchdog.v
+//
+// *Module Description:
+// Watchdog Timer
+//
+// *Author(s):
+// - Olivier Girard, olgirard@gmail.com
+//
+//----------------------------------------------------------------------------
+// $Rev: 34 $
+// $LastChangedBy: olivier.girard $
+// $LastChangedDate: 2009-12-29 20:10:34 +0100 (Tue, 29 Dec 2009) $
+//----------------------------------------------------------------------------
+`include "timescale.v"
+`include "openMSP430_defines.v"
+
+module omsp_watchdog (
+
+// OUTPUTs
+ nmi_evt, // NMI Event
+ per_dout, // Peripheral data output
+ wdtifg_set, // Set Watchdog-timer interrupt flag
+ wdtpw_error, // Watchdog-timer password error
+ wdttmsel, // Watchdog-timer mode select
+
+// INPUTs
+ aclk_en, // ACLK enable
+ dbg_freeze, // Freeze Watchdog counter
+ mclk, // Main system clock
+ nmi, // Non-maskable interrupt (asynchronous)
+ nmie, // Non-maskable interrupt enable
+ per_addr, // Peripheral address
+ per_din, // Peripheral data input
+ per_en, // Peripheral enable (high active)
+ per_wen, // Peripheral write enable (high active)
+ puc, // Main system reset
+ smclk_en, // SMCLK enable
+ wdtie // Watchdog timer interrupt enable
+);
+
+// OUTPUTs
+//=========
+output nmi_evt; // NMI Event
+output [15:0] per_dout; // Peripheral data output
+output wdtifg_set; // Set Watchdog-timer interrupt flag
+output wdtpw_error; // Watchdog-timer password error
+output wdttmsel; // Watchdog-timer mode select
+
+// INPUTs
+//=========
+input aclk_en; // ACLK enable
+input dbg_freeze; // Freeze Watchdog counter
+input mclk; // Main system clock
+input nmi; // Non-maskable interrupt (asynchronous)
+input nmie; // Non-maskable interrupt enable
+input [7:0] per_addr; // Peripheral address
+input [15:0] per_din; // Peripheral data input
+input per_en; // Peripheral enable (high active)
+input [1:0] per_wen; // Peripheral write enable (high active)
+input puc; // Main system reset
+input smclk_en; // SMCLK enable
+input wdtie; // Watchdog timer interrupt enable
+
+
+//=============================================================================
+// 1) PARAMETER DECLARATION
+//=============================================================================
+
+// Register addresses
+parameter WDTCTL = 9'h120;
+
+
+// Register one-hot decoder
+parameter WDTCTL_D = (512'h1 << WDTCTL);
+
+
+//============================================================================
+// 2) REGISTER DECODER
+//============================================================================
+
+// Register address decode
+reg [511:0] reg_dec;
+always @(per_addr)
+ case ({per_addr,1'b0})
+ WDTCTL : reg_dec = WDTCTL_D;
+ default: reg_dec = {512{1'b0}};
+ endcase
+
+// Read/Write probes
+wire reg_write = |per_wen & per_en;
+wire reg_read = ~|per_wen & per_en;
+
+// Read/Write vectors
+wire [511:0] reg_wr = reg_dec & {512{reg_write}};
+wire [511:0] reg_rd = reg_dec & {512{reg_read}};
+
+
+//============================================================================
+// 3) REGISTERS
+//============================================================================
+
+// WDTCTL Register
+//-----------------
+// WDTNMI & WDTSSEL are not implemented and therefore masked
+
+reg [7:0] wdtctl;
+
+wire wdtctl_wr = reg_wr[WDTCTL];
+
+always @ (posedge mclk or posedge puc)
+ if (puc) wdtctl <= 8'h00;
+ else if (wdtctl_wr) wdtctl <= per_din[7:0] & 8'hd7;
+
+wire wdtpw_error = wdtctl_wr & (per_din[15:8]!=8'h5a);
+wire wdttmsel = wdtctl[4];
+
+
+//============================================================================
+// 3) REGISTERS
+//============================================================================
+
+// Data output mux
+wire [15:0] wdtctl_rd = {8'h69, wdtctl} & {16{reg_rd[WDTCTL]}};
+
+wire [15:0] per_dout = wdtctl_rd;
+
+
+//=============================================================================
+// 4) NMI GENERATION
+//=============================================================================
+
+// Synchronization state
+reg [2:0] nmi_sync;
+always @ (posedge mclk or posedge puc)
+ if (puc) nmi_sync <= 3'h0;
+ else nmi_sync <= {nmi_sync[1:0], nmi};
+
+// Edge detection
+wire nmi_re = ~nmi_sync[2] & nmi_sync[0] & nmie;
+wire nmi_fe = nmi_sync[2] & ~nmi_sync[0] & nmie;
+
+// NMI event
+wire nmi_evt = wdtctl[6] ? nmi_fe : nmi_re;
+
+
+//=============================================================================
+// 5) WATCHDOG TIMER
+//=============================================================================
+
+// Watchdog clock source selection
+//---------------------------------
+wire clk_src_en = wdtctl[2] ? aclk_en : smclk_en;
+
+
+// Watchdog 16 bit counter
+//--------------------------
+reg [15:0] wdtcnt;
+
+wire wdtcnt_clr = (wdtctl_wr & per_din[3]) | wdtifg_set;
+
+always @ (posedge mclk or posedge puc)
+ if (puc) wdtcnt <= 16'h0000;
+ else if (wdtcnt_clr) wdtcnt <= 16'h0000;
+ else if (~wdtctl[7] & clk_src_en & ~dbg_freeze) wdtcnt <= wdtcnt+16'h0001;
+
+
+// Interval selection mux
+//--------------------------
+reg wdtqn;
+
+always @(wdtctl or wdtcnt)
+ case(wdtctl[1:0])
+ 2'b00 : wdtqn = wdtcnt[15];
+ 2'b01 : wdtqn = wdtcnt[13];
+ 2'b10 : wdtqn = wdtcnt[9];
+ default: wdtqn = wdtcnt[6];
+ endcase
+
+
+// Watchdog event detection
+//-----------------------------
+reg wdtqn_dly;
+
+always @ (posedge mclk or posedge puc)
+ if (puc) wdtqn_dly <= 1'b0;
+ else wdtqn_dly <= wdtqn;
+
+wire wdtifg_set = (~wdtqn_dly & wdtqn) | wdtpw_error;
+
+
+endmodule // omsp_watchdog
+
+`include "openMSP430_undefines.v"
projects / fpga / openmsp430.git / blobdiff