Solar lamp msp430

main.c

#include <msp430.h>
#include <stdbool.h>

/**
 * slim solarlampje.
 * Doel:
 * aan net voor zonsopgang tot zonsopgang,
 * aan na zonsondergang, maar beperkte tijd (niet hele nacht)
 * dus de "vorige" zonsondergang/opgang onthouden.
 *
 * tellertje van langer dan 24 uur, en steeds resetten bij zonsopgang
 * dan dus bij zonsondergang aan en teller opslaan, bij donkerteller+ietsvan2uur weer uit
 * Als het licht is uit en tellerwaarde opslaan en daarna teller resetten naar 0
 * Dan bij lichtteller-ietsvan2uur aan. En bij licht weer uit ^
 *
 * zonnepaneel om te bepalen of het donker is. Met hysterese van I/O pin en spanningsdeler.
 * (Als dat niet werkt, kan het nog met de ADC)
 *
 */

/* 1 tick = approximately 1,3 -ish seconds. */

#define BEFORESUNRISE 6000 /* ticks before sunrise that LED should turn on. */
/* - previous sunrise is used for this and it waits untill actual sunrise, so it might be on longer */

#define AFTERSUNDOWN 6000 /* Ticks that LED should stay ON after sundown (unless sunrise happens first)*/

#define SUNSTATETICKS 15 /* ticks that sun needs to be up/down cumulative before changing state*/

void main(void)
{
    WDTCTL = WDTPW | WDTHOLD;       // stop watchdog timer
    P1DIR = 0x41;                   // configure P1.0 and P1.6 as output
    // only use pull-up when testing with switch, not with actual solar panel
    //P1REN = (1<<3);                 // enable resistor on P1.3 (switch)
    //P1OUT |= (1<<3);                // pull-up switch
    P2DIR = 0xFF;
    P2OUT = 0x00;

    /* set up timer A for compare interrupt each 1.01s (but clock is variable, so approx 1 s)*/
    TACCR0 = 190;   // Compare value. 12kHz/8/8/190 ~ 1 Hz
    TACCTL0 = CCIE; // enable compare interrupt
    TACTL = TASSEL_1 | ID_3 | MC_1; // ACLK /8, count up to TACCR0

    unsigned long tick, sunup_anticipate=12,sundown_timer=52; /* with tick at 1s and starting from sunup, */
    unsigned int sunstate=SUNSTATETICKS;
    bool onceatsunrise=true, onceatsundown=true, IsSunUp=true;


    /* switch clock from default 1.1M  DCO tot 12 kHz VLOVLK (for low power)
     * and divide by 8 (max division) to slow loop down (and even lower power)
     *
     *  So MCU and pheripherals run at 12/8=1.5 kHz
     *  */
    BCSCTL1 = XT2OFF | DIVA_3;
    BCSCTL2 = SELM_3 | DIVM_3 | DIVS_3 | SELS; /* VLOCLK/8  for MCLK and SMCLK */
    BCSCTL3 = LFXT1S_2; /* VLOCLK (XTS==0)*/

    while(1)
    {
        //P1OUT ^= (1<<0); /* toggle P1.0 for debug*/
        P1OUT = P1OUT&0xFE | IsSunUp; /* P1.0 shows if sun is up or down, for debug */

        tick++;
        if(IsSunUp && onceatsunrise){
            sunup_anticipate = tick - BEFORESUNRISE;
            P1OUT &= ~(1<<6); // uit bij zonsopgang
            tick = 0; /* sync timer to sun */
            onceatsunrise = false; /* do not keep resetting */
            onceatsundown = true; /* prime for sundown */
            }
        if(!IsSunUp && onceatsundown){
            sundown_timer = tick + AFTERSUNDOWN;
            P1OUT |= (1<<6); /* LED on after sundown */
            onceatsundown = false; /* do not keep setting timer / resetting timer */
            onceatsunrise = true; /* prime for sunrise */
        }
        if((onceatsundown==false) && (onceatsunrise==false)){ /* if ever a cosmic ray or EMC or anything causes both to be false, set both true*/
            onceatsunrise = true;
            onceatsundown = true;
        }

        if(tick==sundown_timer){
            P1OUT &= ~(1<<6); // off
        }
        if((tick==sunup_anticipate)&&(IsSunUp==false)){
            P1OUT |= (1<<6); // on
        }

        /* determine if sun is up or down (and filter out clouds etc by needing TBD ticks (30? 60?) of accumulated light or dark). */
        if( (P1IN & 1<<3)==0)
        { /* for now, use I/O with its pin hysteresis as a comparator. If needed, ADC could be used instead, but rather not */
            if(sunstate>0) sunstate--;
        }
        else
        {
            if(sunstate<SUNSTATETICKS) sunstate++;
        }

        if(sunstate>=SUNSTATETICKS-1) IsSunUp = true; else if(sunstate<2) IsSunUp = false;

        __bis_SR_register(LPM3_bits + GIE);       // Enter LPM3 (Untill timer interrupt, so: sleep for approximately 1 s. This makes each tick about 1,3 s.)
        /*TODO: disable this sleep-mode by commenting above line for faster testing.*/
    }
}

#pragma vector=TIMERA0_VECTOR
__interrupt void timera (void)
{
 __bic_SR_register_on_exit(LPM3_bits);                 // Clear LPM3 bits from 0(SR)
}