msp430f2013 ulp pir 0-00.c

MSP430F2013的超低功耗运动检测仪功能描述

//*****************************************************************************
//  Code for application report SLAA283 - "Ultra-low Power Motion Detection
//    using the MSP430F2013"
//
//  Version 0-00
//
//  Version Summary:
//  0-00 released 12-22-2005- Initial release
//
//  Z. Albus
//  Texas Instruments Inc.
//  December 2005
//  Built with IAR Embedded Workbench Version: 3.30B
//*****************************************************************************
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//******************************************************************************
#include  <msp430x20x3.h>

#define   LED_OUT         BIT0              // Bit location for LED
#define   SENSOR_PWR      BIT7              // Bit location for power to sensor
#define   THRESHOLD       50                // Threshold for motion

static unsigned int result_old = 0;         // Storage for last conversion

void main(void)
{
  WDTCTL = WDTPW+WDTTMSEL+WDTCNTCL+WDTSSEL; // ACLK/32768, int timer: ~10s
  BCSCTL1 = CALBC1_1MHZ;                    // Set DCO to 1MHz
  DCOCTL = CALDCO_1MHZ;
  BCSCTL1 |= DIVA_2;                        // ACLK = VLO/4
  BCSCTL3 |= LFXT1S_2;

  P1OUT = 0x10;                             // P1OUTs
  P1SEL = 0x08;                             // Select VREF function
  P1DIR = 0xEF;                             // Unused pins as outputs
  P2OUT = 0x00 + SENSOR_PWR;                // P2OUTs
  P2SEL &= ~SENSOR_PWR;                     // P2.7 = GPIO
  P2DIR = 0xff;                             // Unused pins as outputs

  SD16CTL = SD16VMIDON + SD16REFON + SD16SSEL_1;// 1.2V ref, SMCLK
  SD16INCTL0 = SD16GAIN_4 + SD16INCH_4;     // PGA = 4x, Diff inputs A4- & A4+
  SD16CCTL0 =  SD16SNGL + SD16IE;           // Single conversion, 256OSR, Int enable
  SD16CTL &= ~SD16VMIDON;                   // VMID off: used to settle ref cap
  SD16AE = SD16AE1 + SD16AE2;               // P1.1 & P1.2: A4+/- SD16_A inputs

  // Wait for PIR sensor to settle: 1st WDT+ interval
  P1SEL |= LED_OUT;                         // Turn LED on with ACLK (for low Icc)
  while(!(IFG1 & WDTIFG));                  // ~5.4s delay: PIR sensor settling
  P1SEL &= ~LED_OUT;                        // Turn LED off with ACLK (for low Icc)

  // Reconfig WDT+ for normal operation: interval of ~341msec
  WDTCTL = WDTPW+WDTTMSEL+WDTCNTCL+WDTSSEL+WDTIS1;// ACLK/512, int timer: 341msec
  BCSCTL1 |= DIVA_3;                        // ACLK = VLO/8
  IE1 |= WDTIE;                             // Enable WDT interrupt

  _BIS_SR(LPM3_bits + GIE);                 // Enter LPM3 with interrupts
}

/******************************************************
// SD16_A interrupt service routine
******************************************************/
#pragma vector = SD16_VECTOR
__interrupt void SD16ISR(void)
{ unsigned int result_new;

  SD16CTL &= ~SD16REFON;                    // Turn off SD16_A ref
  result_new = SD16MEM0;                    // Save result (clears IFG)

  if (result_new > result_old)              // Get difference between samples
    result_old = result_new - result_old;
  else
    result_old = result_old - result_new;

  if (result_old > THRESHOLD)               // If motion detected...
     P1OUT |= LED_OUT;                      // Turn LED on

  result_old = SD16MEM0;                    // Save last conversion

  __bis_SR_register_on_exit(SCG1+SCG0);     // Return to LPM3 after reti
}

/******************************************************
// Watchdog Timer interrupt service routine
******************************************************/
#pragma vector=WDT_VECTOR
__interrupt void watchdog_timer(void)
{
  if (!(P1OUT & LED_OUT))                   // Has motion already been detected?
  {
    SD16CTL |= SD16REFON;                   // If no, turn on SD16_A ref
    SD16CCTL0 |= SD16SC;                    // Set bit to start new conversion
    __bic_SR_register_on_exit(SCG1+SCG0);   // Keep DCO & SMCLK on after reti
  }
  else
    P1OUT &= ~LED_OUT;                      // If yes, turn off LED, measure on next loop
}