View source for MSP430G2553 as a watchdog

*TI launchpad 430 is supplied with [MSP430G2553 in DIP20 package] on board.
*Below is the code for a simple watchdog, 
:*P1.6 output is activated every ~12hours 
:*P1.4 polls for an active signal that resets (pets) the watchdog timer every 10ms.
*The output line P1.6 is used to drive a mosfet switch that is controlling the system power-supply, so it is HIGH most of the time and goes LOW for 10s every 12 hours (if not reset by P1.4 line)
*Current consumption measured at 70uA
*Tested with CCS5, IAR and Energia
*line P1.0, ~10ms interrupt measurement: [[File:msp430g2553_switch.JPG|400px]]
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*CCS5 and IAR Embedded Workbench 5.6 (kickstart license) code
<cpp>
//BUOY TIMER
#include <msp430g2553.h>
#define ten_ms    115 //230
#define one_sec   20000
#define time2reset 4320000 //2160000  //4320000 // 43200 sec is 3600sec/hour x 12 hours, int is at 10Hz
#define time2set   4321000 //2160500  //4321000 // 10 seconds active output
volatile unsigned long counter = 4319000; //  TESTING AT POWER ON, TURNS BUOY OFF FOR 10sec, 10sec after power-on

void main(void) {
  DCOCTL = CALDCO_1MHZ;            // Set DCO to 1MHz
  BCSCTL1 = CALBC1_1MHZ;           // Set DCO to 1MHz
  BCSCTL3 |= LFXT1S_2;             // Select VLO for ACLK

  WDTCTL = WDTPW + WDTHOLD;        // Stop watchdog timer, WILL BE ACTIVATED BY ISR
  P1REN = BIT7+BIT5+BIT4+BIT3+BIT2+BIT1;  // ENABLE P1 inputs PULL UP/DOWN
  P1OUT = 0;                       // P1 inputs  PULL-DOWN
  P2REN = BIT0 + BIT1 + BIT2 + BIT3 + BIT4 + BIT5;  // ENABLE P2 (6 available on chip) PULL UP/DOWN
  P1DIR |= BIT0;                   // Set P1.0 to output direction
  P1OUT &= ~BIT0;                  // Set the red LED off
  P1DIR |= BIT6;                   // Set P1.6 to output direction, contols the MOSFET-SWITCH
  P1OUT |= BIT6;                   // OUTPUT HIGH, BUOY IS ACTIVE
  TA0CCR0 = ten_ms;                // Count limit (16 bit), set the Interrupt period
  TA0CCTL0 = 0x10;                 // Enable Timer A0 interrupts, bit 4=1
  TA0CTL = TASSEL_1 + MC_1;        // Timer A0 with ACLK, count UP
 _BIS_SR(LPM3_bits + GIE);        // set LPM3,  interrupts enabled
}

#pragma vector=TIMER0_A0_VECTOR    // Timer0 A0 interrupt service routine
  __interrupt void Timer0_A0 (void) {
   WDTCTL = WDTPW + WDTCNTCL ;      //pet the dog
   P1OUT ^= BIT0;                   //isr is active, to oscilloscope
   counter = counter + 1;
   if (P1IN & BIT4) counter = 0;    // 10ms Polling for a timer-clear signal
   if (counter == time2reset)  {
     P1OUT &= ~BIT6;                // RESET output
   }
   else if (counter > time2set) {
     P1OUT |= BIT6;                 // SET output
     counter = 0;
   }
}
</cpp>


*Energia (sketch) code
<cpp>
volatile unsigned long counter = 4319000; //  TESTING AT POWER ON, TURNS BUOY OFF FOR 10sec, 10sec after power-on

void setup()
{
//BUOY TIMER
 #include <msp430g2553.h>
 #define ten_ms    115 //230
 #define one_sec   20000
 #define time2reset 4320000 //2160000  //4320000 // 43200 sec is 3600sec/hour x 12 hours, int is at 10Hz
 #define time2set   4321000 //2160500  //4321000 // 10 seconds active output
 
  DCOCTL = CALDCO_1MHZ;            // Set DCO to 1MHz
  BCSCTL1 = CALBC1_1MHZ;           // Set DCO to 1MHz
  BCSCTL3 |= LFXT1S_2;             // Select VLO for ACLK
 
  WDTCTL = WDTPW + WDTHOLD;        // Stop watchdog timer, WILL BE ACTIVATED BY ISR
  P1REN = BIT7+BIT5+BIT4+BIT3+BIT2+BIT1;  // ENABLE P1 inputs PULL UP/DOWN
  P1OUT = 0;                       // P1 inputs  PULL-DOWN
  P2REN = BIT0 + BIT1 + BIT2 + BIT3 + BIT4 + BIT5;  // ENABLE P2 (6 available on chip) PULL UP/DOWN
  P1DIR |= BIT0;                   // Set P1.0 to output direction
  P1OUT &= ~BIT0;                  // Set the red LED off
  P1DIR |= BIT6;                   // Set P1.6 to output direction, contols the MOSFET-SWITCH
  P1OUT |= BIT6;                   // OUTPUT HIGH, BUOY IS ACTIVE
  TA0CCR0 = ten_ms;                // Count limit (16 bit), set the Interrupt period
  TA0CCTL0 = 0x10;                 // Enable Timer A0 interrupts, bit 4=1
  TA0CTL = TASSEL_1 + MC_1;        // Timer A0 with ACLK, count UP
 _BIS_SR(LPM3_bits + GIE);        // set LPM3,  interrupts enabled
}

void loop()
{
  // put your main code here, to run repeatedly:  
}

#pragma vector=TIMER0_A0_VECTOR    // Timer0 A0 interrupt service routine
  __interrupt void Timer0_A0 (void) {
   WDTCTL = WDTPW + WDTCNTCL ;      //pet the dog
   P1OUT ^= BIT0;                   //isr is active, to oscilloscope
   counter = counter + 1;
   if (P1IN & BIT4) counter = 0;    // 10ms Polling for a timer-clear signal
   if (counter == time2reset)  {
     P1OUT &= ~BIT6;                // RESET output
   }
   else if (counter > time2set) {
     P1OUT |= BIT6;                 // SET output
     counter = 0;
   }
}
</cpp>


{{Cat1|MSP430}}