1 | #include <msp430x20x3.h>
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2 |
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3 | #define LED_OUT BIT0 // Bit location for LED
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4 | #define SENSOR_PWR BIT7 // Bit location for power to sensor
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5 | #define THRESHOLD 50 // Threshold for motion
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6 |
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7 | static unsigned int result_old = 0; // Storage for last conversion
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8 | char LED_ENABLE = 1; // LED control
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9 |
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10 | void main(void)
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11 | {
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12 | WDTCTL = WDTPW+WDTTMSEL+WDTCNTCL+WDTSSEL; // ACLK/32768, int timer: ~10s
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13 | BCSCTL1 = CALBC1_1MHZ; // Set DCO to 1MHz
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14 | DCOCTL = CALDCO_1MHZ;
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15 | BCSCTL1 |= DIVA_2; // ACLK = VLO/4
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16 | BCSCTL3 |= LFXT1S_2;
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17 |
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18 | P1OUT = 0x10; // P1OUTs
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19 | P1SEL = 0x08; // Select VREF function
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20 | P1DIR = 0xEF; // Unused pins as outputs
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21 | P1REN |= 0x10; // P1.4 pullup
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22 | P1IE |= 0x10; // P1.4 interrupt enabled
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23 | P1IES |= 0x10; // P1.4 Hi/lo edge
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24 | P1IFG &= ~0x10; // P1.4 IFG cleared
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25 | P2OUT = 0x00 + SENSOR_PWR; // P2OUTs
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26 | P2SEL &= ~SENSOR_PWR; // P2.7 = GPIO
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27 | P2DIR = 0xff; // Unused pins as outputs
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28 |
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29 | SD16CTL = SD16VMIDON + SD16REFON + SD16SSEL_1;// 1.2V ref, SMCLK
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30 | SD16INCTL0 = SD16GAIN_4 + SD16INCH_4; // PGA = 4x, Diff inputs A4- & A4+
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31 | SD16CCTL0 = SD16SNGL + SD16IE; // Single conversion, 256OSR, Int enable
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32 | SD16CTL &= ~SD16VMIDON; // VMID off: used to settle ref cap
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33 | SD16AE = SD16AE1 + SD16AE2; // P1.1 & P1.2: A4+/- SD16_A inputs
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34 |
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35 | // Wait for PIR sensor to settle: 1st WDT+ interval
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36 | P1SEL |= LED_OUT; // Turn LED on with ACLK (for low Icc)
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37 | while(!(IFG1 & WDTIFG)); // ~5.4s delay: PIR sensor settling
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38 | P1SEL &= ~LED_OUT; // Turn LED off with ACLK (for low Icc)
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39 |
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40 | // Reconfig WDT+ for normal operation: interval of ~341msec
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41 | WDTCTL = WDTPW+WDTTMSEL+WDTCNTCL+WDTSSEL+WDTIS1;// ACLK/512, int timer: 341msec
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42 | BCSCTL1 |= DIVA_3; // ACLK = VLO/8
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43 | IE1 |= WDTIE; // Enable WDT interrupt
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44 |
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45 | _BIS_SR(LPM3_bits + GIE); // Enter LPM3 with interrupts
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46 | }
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47 |
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48 | /******************************************************
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49 | // SD16_A interrupt service routine
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50 | ******************************************************/
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51 | #pragma vector = SD16_VECTOR
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52 | __interrupt void SD16ISR(void)
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53 | { unsigned int result_new;
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54 |
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55 | SD16CTL &= ~SD16REFON; // Turn off SD16_A ref
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56 | result_new = SD16MEM0; // Save result (clears IFG)
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57 |
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58 | if (result_new > result_old) // Get difference between samples
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59 | result_old = result_new - result_old;
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60 | else
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61 | result_old = result_old - result_new;
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62 |
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63 | if (result_old > THRESHOLD) // If motion detected...
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64 | if (LED_ENABLE & 0x01)
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65 | P1OUT |= LED_OUT; // Turn LED on
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66 |
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67 | result_old = SD16MEM0; // Save last conversion
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68 |
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69 | __bis_SR_register_on_exit(SCG1+SCG0); // Return to LPM3 after reti
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70 | }
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71 |
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72 | /******************************************************
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73 | // Watchdog Timer interrupt service routine
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74 | ******************************************************/
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75 | #pragma vector=WDT_VECTOR
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76 | __interrupt void watchdog_timer(void)
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77 | {
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78 | if (!(P1OUT & LED_OUT)) // Has motion already been detected?
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79 | {
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80 | SD16CTL |= SD16REFON; // If no, turn on SD16_A ref
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81 | SD16CCTL0 |= SD16SC; // Set bit to start new conversion
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82 | __bic_SR_register_on_exit(SCG1+SCG0); // Keep DCO & SMCLK on after reti
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83 | }
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84 | else
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85 | P1OUT &= ~LED_OUT; // If yes, turn off LED, measure on next loop
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86 | }
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87 |
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88 | // Port 1 interrupt service routine
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89 | #pragma vector=PORT1_VECTOR
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90 | __interrupt void Port_1(void)
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91 | {
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92 | LED_ENABLE ^= 0x01; // Toggle LED enable for current measurement
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93 | P1IFG &= ~0x10; // P1.4 IFG cleared
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94 | }
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