Watchdog.cpp

00001 /// @file Watchdog.cpp provides the interface to the Watchdog module
00002 ///
00003 /// This provides basic Watchdog service for the mbed. You can configure
00004 /// various timeout intervals that meet your system needs. Additionally,
00005 /// it is possible to identify if the Watchdog was the cause of any 
00006 /// system restart.
00007 /// 
00008 /// Adapted from Simon's Watchdog code from http://mbed.org/forum/mbed/topic/508/
00009 ///
00010 /// @note Copyright © 2011 by Smartware Computing, all rights reserved.
00011 ///     This software may be used to derive new software, as long as
00012 ///     this copyright statement remains in the source file.
00013 /// @author David Smart
00014 ///
00015 #include "mbed.h"
00016 #include "Watchdog.h"
00017 
00018 
00019 #if defined( TARGET_LPC1768 )
00020 /// Watchdog gets instantiated at the module level
00021 Watchdog::Watchdog() {
00022     wdreset = (LPC_WDT->WDMOD >> 2) & 1;    // capture the cause of the previous reset
00023 }
00024 
00025 /// Load timeout value in watchdog timer and enable
00026 void Watchdog::Configure(float s) {
00027     LPC_WDT->WDCLKSEL = 0x1;                // Set CLK src to PCLK
00028     uint32_t clk = SystemCoreClock / 16;    // WD has a fixed /4 prescaler, PCLK default is /4
00029     LPC_WDT->WDTC = (uint32_t)(s * (float)clk);
00030     LPC_WDT->WDMOD = 0x3;                   // Enabled and Reset
00031     Service();
00032 }
00033 
00034 /// "Service", "kick" or "feed" the dog - reset the watchdog timer
00035 /// by writing this required bit pattern
00036 void Watchdog::Service() {
00037     LPC_WDT->WDFEED = 0xAA;
00038     LPC_WDT->WDFEED = 0x55;
00039 }
00040 
00041 /// get the flag to indicate if the watchdog causes the reset
00042 bool Watchdog::WatchdogCausedReset() {
00043     return wdreset;
00044 }
00045 #elif defined( TARGET_LPC4088 )
00046 /// Watchdog gets instantiated at the module level
00047 Watchdog::Watchdog() {
00048     wdreset = (LPC_WDT->MOD >> 2) & 1;    // capture the cause of the previous reset
00049 }
00050 
00051 /// Load timeout value in watchdog timer and enable
00052 void Watchdog::Configure(float s) {
00053     //LPC_WDT->CLKSEL = 0x1;                // Set CLK src to PCLK
00054     uint32_t clk = 500000 / 4;    // WD has a fixed /4 prescaler, and a 500khz oscillator
00055     LPC_WDT->TC = (uint32_t)(s * (float)clk);
00056     LPC_WDT->MOD = 0x3;                   // Enabled and Reset
00057     Service();
00058 }
00059 
00060 /// "Service", "kick" or "feed" the dog - reset the watchdog timer
00061 /// by writing this required bit pattern
00062 void Watchdog::Service() {
00063     LPC_WDT->FEED = 0xAA;
00064     LPC_WDT->FEED = 0x55;
00065 }
00066 
00067 /// get the flag to indicate if the watchdog causes the reset
00068 bool Watchdog::WatchdogCausedReset() {
00069     return wdreset;
00070 }
00071 #endif
00072