implement watchdog

1 files changed, 43 insertions, 6 deletions

diff --git a/main.c b/main.c
index 4a299e9..809d432 100644
--- a/main.c
+++ b/main.c
@@ -30,11 +30,16 @@
  * with the EP80579 standard ACPI subsystem. Likewise for the reset button.
  */
 
+/* define WATCHDOG to get one :) */
+#define WATCHDOG
+//#undef WATCHDOG
+
 /* define TRACE_SERIAL to get debugging traces capabilities on the
  * MSP430 serial port
  * WARNING: This might disable some functions too, check the code
  * to see exactly what that does in this particular version */
-#define TRACE_SERIAL
+//#define TRACE_SERIAL
+#undef TRACE_SERIAL
 
 /* define LOOP_REBOOT if you want that the board reboot forever
  * define it to the number of ms to spend in the WAIT_STOP state.
@@ -239,7 +244,9 @@ int main(void)
 {
   u16 state, resetState;
 
-  WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer to prevent time out reset
+#ifndef WATCHDOG
+  WDTCTL = WDTPW | WDTHOLD;
+#endif /* WATCHDOG */
 
   __disable_interrupt();
 
@@ -433,6 +440,11 @@ int main(void)
 #pragma vector = TIMERA1_VECTOR
 __interrupt void Timer_A(void)
 {
+#ifdef WATCHDOG
+  /* ACLK (VLO) /64 => T belongs to [0.016; 0.0032] s */
+  WDTCTL = WDTPW | WDCNTCL | WDTSSEL | WTDIS1 | WTDIS0;
+#endif /* WATCHDOG */
+
   if (!(P1IN & START_SW1_N))
     SW1State++;
   else
@@ -491,15 +503,40 @@ static void InitPorts(void)
 
 static void GlobalInit(void)
 {
+  /******** MCLK SMCLK ACLK Configuration ********/
+
   /* freq selection procedure compliant with errata BCL12
    * (potentially switching from RSEL < 12 to > 13)
    */
   DCOCTL = 0;
-  BCSCTL1 = CALBC1_12MHZ;
+                        /* LFXT1 low freq (to allow for VLO), ACLK will be /1 */
+  BCSCTL1 = CALBC1_12MHZ & ~(XTS | DIVA0 | DIVA1);
   DCOCTL = CALDCO_12MHZ;
 
-  TACTL = TASSEL_2 + ID_3 + TACLR + TAIE + MC_1; // SMCLK + div by 8 + reset +
-                                                 // enable interrupt + UP
+  BCSCTL3 = LFXT1S_2 /* VLO */;
+
+  /* Status here:
+   *    MCLK and SMCLK from DCO, 12MHz nominal.
+   *    ACLK from VLOCLK, 4 -> 20kHz.
+   */
+
+
+#ifdef WATCHDOG
+  /******** Watchdog early configuration ********/
+
+                            /* ACLK   /8192 */
+  WDTCTL = WDTPW + WDCNTCL + WDTSSEL + WTDIS0;
+  /* This initial WDT will expire in 0.4 to 2.1 s
+   * Note that it will be reconfigured to expire with shorter intervals
+   * starting from the next clearing.
+   */
+#endif /* WATCHDOG */
+
+
+  /********  Timer A configuration ********/
+
+  TACTL = TASSEL_2 | ID_3 | TACLR | TAIE | MC_1; // SMCLK | div by 8 | reset |
+                                                 // enable interrupt | UP
 
   // Calibrated DCO Frequencies - Tolerance Over Temperature 0C to 85C
   //
@@ -517,5 +554,5 @@ static void GlobalInit(void)
   // >>> 1539 / 1500000. * 1.025
   // 0.00105165                       1.052 ms max
 
-  TACCR0 = 1539 + 1; /* TA16 errata */
+  TACCR0 = 1539 + 1; /* TA16 errata => + 1 => so T belongs to [1.000 ; 1.053] */
 }