// solar powered remote temperature/humidity/illumination sensor
// using xbee xb24 radio. 
// epv 2/2011

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include <avr/wdt.h>
#include <avr/sleep.h>
#include <util/delay.h>
#include "serial.h"
#include "sht15.h" 

#define MYREF _BV(REFS0)
#define BLINK() { PORTB |= _BV(0); _delay_ms(50); PORTB &= ~_BV(0); }
#define VDIV_ON() { PORTC |= _BV(3); }
#define VDIV_OFF() { PORTC &= ~_BV(3); }
#define WAKE_MODEM() { PORTD &= ~_BV(2); }
#define SLEEP_MODEM() { PORTD |= _BV(2); }
#define WAIT() { _delay_ms(100); getchar(); getchar(); getchar(); }
#define VDIV_CONST 155.00 // ratio of ADC value to voltage before divider
#define NUMSLEEPS 3 // 3 = about 25 seconds with "8" sec WDT

ISR(WDT_vect) { }
ISR(ADC_vect) { }

void go_to_sleep(void);

uint16_t read_adc(uint8_t chan)
{
  ADCSRA = _BV(ADEN) | _BV(ADPS2) | _BV(ADPS1) | _BV(ADPS0) | _BV(ADIE);
  set_sleep_mode(SLEEP_MODE_ADC);
  ADMUX = chan | MYREF;
  ADCSRA |= _BV(ADSC);
  sleep_mode();
  return(ADCW);
}

int main(void)
{
  uint16_t batt, light, sum, count=0;
  uint8_t i;
  double temp, rh; // data from SHT15
  
  char logline[58];
  FILE uart_str = FDEV_SETUP_STREAM(uart_putchar, uart_getchar, _FDEV_SETUP_RW);

  init_usart();
  _delay_ms(100);
  stdout = stdin = &uart_str; 

  // IO pins setup
  DDRB |= _BV(0);	// blue LED
  DDRD |= _BV(2); // wake line to XBee
  DDRD &= ~_BV(3); // CTS line from XBee
  DDRC |= _BV(3); // switch for battery voltage divider
  PORTC &= ~_BV(3); // leave it off
  DDRC |= (1<<5); // C5 = SHT15 clock line
  BLINK();
  sht_reset();
  WAKE_MODEM();

  _delay_ms(1020); printf("+++"); _delay_ms(1020);
  printf("ATCE0\r\n"); WAIT();
  printf("ATID3332\r\n"); WAIT(); // pan id
  printf("ATMY01\r\n"); WAIT();   // my address
  printf("ATDL02\r\n"); WAIT();   // dest address
  printf("ATSM1\r\n"); WAIT();    // cycl sleep mode, let pin wake it too
  printf("ATCN\r\n"); WAIT();     // back to cmd mode.

  BLINK();
  printf("I'm alive!\r\n");
  sei();
  _delay_ms(50);

  while(1) { 
    BLINK();
    // take data before powering up radio to save power.
    VDIV_ON(); _delay_ms(15); // SHT15 needs 11ms before talking to it
    batt=read_adc(2);
    light=read_adc(1);
    temp=sht_temp();
    rh=sht_humidity_comp(temp);
    VDIV_OFF();

    WAKE_MODEM();  // now we're drawing lots of current
    while((PIND & _BV(3)) != 0); // wait for CTS
    _delay_ms(20);
    memset(logline, 0, sizeof(logline));
    sprintf_P(logline,PSTR("unit2 %u %.2fv %.1f%% illum %.2f degF %.2f%% rh"), 
	      count++, batt / VDIV_CONST, light/10.24, (temp*9/5)+32, rh);
    sum=CalcCRC(0xFFFFFFFF, logline, sizeof(logline));
    printf("%s %04x\r\n", logline, sum);
    _delay_ms(90);
    SLEEP_MODEM();
    for(i=0; i<NUMSLEEPS; i++) 
      go_to_sleep();
  }
}

void go_to_sleep(void)
{
  // housekeeping, and hibernate until next wakeup
  SLEEP_MODEM();
  wdt_enable(WDTO_8S); // wake up every 8-10 sec
  WDTCSR |= _BV(WDIE); // watchdog just generates interrupt, not reset
  set_sleep_mode(SLEEP_MODE_PWR_DOWN); // complete shutdown
  ADCSRA &= ~_BV(ADEN); // turn off ADC
  sleep_mode();
  wdt_disable();
}