Diff: main.cpp

Revision:

0:c1e30d3d8237

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Aug 30 13:17:29 2018 +0000
@@ -0,0 +1,65 @@
+#include "mbed.h"
+
+// LEDs used to indicate code activity and reset source
+DigitalOut myled1(LED1); //in main loop part 1
+DigitalOut myled2(LED2); //in main loop part 2
+
+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;
+    }
+};
+
+
+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) {
+        printf("\n\nWDT reset\n");
+    } else {
+        printf("\n\nnice reset\n");
+    }
+
+// setup a 5 second timeout on watchdog timer hardware
+// needs to be longer than worst case main loop exection time
+    wdt.kick(5.0);
+
+    printf("going in while 1\n");
+// Main program loop - resets watchdog once each loop iteration
+// Would typically have a lot of code in loop with many calls
+    while (1) {
+        myled1 = 1; //Flash LEDs 1 & 2 to indicate normal loop activity
+        wait(.5);
+        myled1 = 0;
+        myled2 = 1;
+        wait(.5);
+        // Simulate a fault lock up with an infinite while loop, but only after 10 loop iterations
+        if (count == 10) {
+            printf("software stuck\n");
+            while (1) {
+            }
+        };
+
+// LED 2 will stay on during the fault
+        myled2 = 0;
+        count ++;
+// End of main loop so "kick" to reset watchdog timer and avoid a reset
+        wdt.kick();
+    }
+}
\ No newline at end of file