// *****************************************************************************
// Fred's LegoLight software
// The majority of this code is from:
// Code for application report SLAA283 - "Ultra-low Power Motion Detection using the MSP430F2013"
// PWM info from http://www.msp430launchpad.com/2010/07/timers-and-clocks-and-pwm-oh-my.html
// ******************************************************************************
#include  <msp430f2013.h>

#define PIR_THRESHOLD   50              	// Threshold for motion
#define LIGHT_ON_TIME   60					// x about .5s = 30s
#define FADE_STEP		50

// P1
#define LED_OUT         BIT0              	// Bit location for LED
#define LIGHT_OUT       BIT6

// P2
#define SENSOR_PWR      BIT7              	// Bit location for power to sensor

static unsigned int result_old = 0;         // Storage for last PIR conversion
static int lightTimer = 0;
static volatile int dutyCycle = 0;

void main(void)
{
  // Use WD to wait about 10s
  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;

  P1DIR = LED_OUT | LIGHT_OUT;
  P1OUT = LED_OUT;
  P1SEL = LIGHT_OUT;						// TA1

  P2OUT = SENSOR_PWR;
  P2DIR = SENSOR_PWR;
  P2SEL = 0x00;

  // Let PIR settle for 10s
  while(!(IFG1 & WDTIFG));
  P1OUT &= ~LED_OUT;

  // Set up PWM using Timer A
  CCR0 = 1000;                            	// PWM Period
  CCTL1 = OUTMOD_7;                         // CCR1 reset/set
  CCR1 = 0;                               	// Initial CCR1 PWM duty cycle
  TACTL = TASSEL_2 + MC_1;                  // SMCLK, up mode

  CCR1 = dutyCycle;

  // 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


  SD16CTL = SD16VMIDON + SD16REFON + SD16SSEL_1; // 1.2V ref, SMCLK
  SD16AE = SD16AE1 | SD16AE2;                     // P1.1 & P1.2:  A4+/- SD16_A inputs
  SD16CTL &= ~SD16VMIDON;                        // VMID off: used to settle ref cap


  _BIS_SR(LPM0_bits + GIE);
}

void adcStartReadPIR(void)
{
    SD16INCTL0 = SD16GAIN_4 + SD16INCH_4;       // PGA = 4x, Diff inputs A4- & A4+
    SD16CCTL0 =  SD16SNGL + SD16IE;             // Single conversion, 256OSR, Int enable
    SD16CTL |= SD16REFON;                   	// If no, turn on SD16_A ref
    SD16CCTL0 |= SD16SC;                        // Set bit to start new conversion
}


#pragma vector = SD16_VECTOR
__interrupt void SD16ISR(void)
{
    //checkPIR();
    // See if we've had movement
    volatile unsigned int result_new;
    volatile unsigned int change;

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

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

    result_old = SD16MEM0;                    // Save last conversion

    // If motion detected...
    if (change > PIR_THRESHOLD)
    {
        // LED indicator
        P1OUT |= LED_OUT;

        // Reset counter
        lightTimer = LIGHT_ON_TIME;

    }
    else
    {
        P1OUT &= ~LED_OUT;
    }

     __bis_SR_register_on_exit(LPM0_bits);
}

// Watchdog Timer interrupt service routine
#pragma vector=WDT_VECTOR
__interrupt void watchdog_timer(void)
{

    // Light on?
    if (lightTimer > 0)
    {
    	// Fade up Light
    	if (dutyCycle < 1000) {
    		dutyCycle += FADE_STEP;
    		CCR1 = dutyCycle;
    	}

        // Tick, tick, tick
    	lightTimer--;
    	// We need to keep SMCLK on as we're using PWM
    	__bic_SR_register_on_exit(LPM0_bits);
    }
    else
    {
    	// Fade down light is off
    	if (dutyCycle > 0)
    	{
    		dutyCycle -= FADE_STEP;
    		CCR1 = dutyCycle;
    	}
    	// We can save some battery using low power mode 3
    	__bic_SR_register_on_exit(LPM3_bits);
    }

    // Has motion already been detected?
    if (P1OUT & LED_OUT)
        P1OUT &= ~LED_OUT;  // If yes, turn off LED, measure on next loop
    else
        adcStartReadPIR();

}

// Port 1 interrupt service routine
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{

}