Revision 0:846bdf8c596c, committed 2018-10-16

Comitter:

kzar

Date:

Tue Oct 16 19:00:04 2018 +0000

Commit message:

Watchdog timer example using led

Changed in this revision

diff -r 000000000000 -r 846bdf8c596c main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Oct 16 19:00:04 2018 +0000
@@ -0,0 +1,56 @@
+#include "mbed.h"
+// LEDs used to indicate code activity and reset source
+DigitalOut myled3(LED3); //The pushbutton or power on caused a reset
+DigitalOut myled4(LED4); //The watchdog timer caused a reset
+
+//Pushbutton and led
+DigitalIn pb(p21);
+DigitalOut led(p23);
+ 
+// Simon's Watchdog code from
+// http://mbed.org/forum/mbed/topic/508/
+class Watchdog {
+public:
+// Load timeout value in watchdog timer and enable
+    void kick(float s) {
+        LPC_WDT->WDCLKSEL = 0x1;                // Set CLK src to PCLK
+        uint32_t clk = SystemCoreClock / 16;    // WD has a fixed /4 prescaler, PCLK default is /4
+        LPC_WDT->WDTC = s * (float)clk;
+        LPC_WDT->WDMOD = 0x3;                   // Enabled and Reset
+        kick();
+    }
+// "kick" or "feed" the dog - reset the watchdog timer
+// by writing this required bit pattern
+    void kick() {
+        LPC_WDT->WDFEED = 0xAA;
+        LPC_WDT->WDFEED = 0x55;
+    }
+};
+ 
+// Setup the watchdog timer
+Watchdog wdt;
+ 
+int main() {
+    int count = 0;
+    // On reset, indicate a watchdog reset or a pushbutton reset on LED 4 or 3
+    if ((LPC_WDT->WDMOD >> 2) & 1)
+        myled4 = 1; else myled3 = 1;
+        
+    // setup a 10 second timeout on watchdog timer hardware
+    // needs to be longer than worst case main loop exection time
+    wdt.kick(3.0);  
+ 
+ 
+    // Main program loop - resets watchdog once each loop iteration
+    // Would typically have a lot of code in loop with many calls
+    while (1) {
+        led = pb;
+        wait(.1);
+        if (count == 50) { 
+            while(1) {} 
+        }
+        count++;
+        // End of main loop so "kick" to reset watchdog timer and avoid a reset
+        wdt.kick();
+    }
+}

diff -r 000000000000 -r 846bdf8c596c mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Tue Oct 16 19:00:04 2018 +0000
@@ -0,0 +1,1 @@
+https://os.mbed.com/users/mbed_official/code/mbed/builds/a7c7b631e539
\ No newline at end of file