ttn_temphumi_battery.ino

/*******************************************************************************
 * Code adapted for the Node Building Workshop using a modified LoraTracker board
 * 
 * 
 * 
 * 
 * Copyright (c) 2015 Thomas Telkamp and Matthijs Kooijman
 *
 * Permission is hereby granted, free of charge, to anyone
 * obtaining a copy of this document and accompanying files,
 * to do whatever they want with them without any restriction,
 * including, but not limited to, copying, modification and redistribution.
 * NO WARRANTY OF ANY KIND IS PROVIDED.
 *
 * This example will send Temperature and Humidity
 * using frequency and encryption settings matching those of
 * the The Things Network. Application will 'sleep' 7x8 seconds (56 seconds)
 *
 * This uses OTAA (Over-the-air activation), where where a DevEUI and
 * application key is configured, which are used in an over-the-air
 * activation procedure where a DevAddr and session keys are
 * assigned/generated for use with all further communication.
 *
 * Note: LoRaWAN per sub-band duty-cycle limitation is enforced (1% in
 * g1, 0.1% in g2), but not the TTN fair usage policy (which is probably
 * violated by this sketch when left running for longer)!

 * To use this sketch, first register your application and device with
 * the things network, to set or generate an AppEUI, DevEUI and AppKey.
 * Multiple devices can use the same AppEUI, but each device has its own
 * DevEUI and AppKey.
 *
 * Do not forget to define the radio type correctly in config.h.
 *
 *******************************************************************************/

#include <avr/sleep.h>
#include <avr/wdt.h>
#include <lmic.h>
#include <hal/hal.h>
#include <SPI.h>
#include "LowPower.h"
#include <Wire.h>
#include "i2c.h"

#include "i2c_SI7021.h"
SI7021 si7021;
#include <Arduino.h>

int sleepcycles = 7;  // every sleepcycle will last 8 secs, total sleeptime will be sleepcycles * 8 sec
bool joined = false;
bool sleeping = false;
#define LedPin 10     // pin 13 LED is not used, because it is connected to the SPI port
#define BatteryThreshold 320  // depending on voltage divider and experiments

// This EUI must be in little-endian format, so least-significant-byte
// first. When copying an EUI from ttnctl output, this means to reverse
// the bytes. For TTN issued EUIs the last bytes should be 0xD5, 0xB3,
// 0x70.
 
static const u1_t DEVEUI[8]  = { };
static const u1_t APPEUI[8] = {  };

// This key should be in big endian format (or, since it is not really a
// number but a block of memory, endianness does not really apply). In
// practice, a key taken from ttnctl can be copied as-is.
// The key shown here is the semtech default key.
static const u1_t APPKEY[16] = { };

// provide APPEUI (8 bytes, LSBF)
void os_getArtEui (u1_t* buf) {
  memcpy(buf, APPEUI, 8);
}

// provide DEVEUI (8 bytes, LSBF)
void os_getDevEui (u1_t* buf) {
  memcpy(buf, DEVEUI, 8);
}

// provide APPKEY key (16 bytes)
void os_getDevKey (u1_t* buf) {
  memcpy(buf, APPKEY, 16);
}

static osjob_t sendjob;
static osjob_t initjob;

// Pin mapping is hardware specific.
// Pin mapping
const lmic_pinmap lmic_pins = {
    .nss = 8,
    .rxtx = LMIC_UNUSED_PIN,
    .rst = 9,
    .dio = {2,5, LMIC_UNUSED_PIN}, //DIO0 and DIO1 connected
};


void onEvent (ev_t ev) {
  int i,j;
  switch (ev) {
    case EV_SCAN_TIMEOUT:
      Serial.println(F("EV_SCAN_TIMEOUT"));
      break;
    case EV_BEACON_FOUND:
      Serial.println(F("EV_BEACON_FOUND"));
      break;
    case EV_BEACON_MISSED:
      Serial.println(F("EV_BEACON_MISSED"));
      break;
    case EV_BEACON_TRACKED:
      Serial.println(F("EV_BEACON_TRACKED"));
      break;
    case EV_JOINING: 
      Serial.println(F("EV_JOINING"));
      break;
    case EV_JOINED:
      Serial.println(F("EV_JOINED"));
      // Disable link check validation (automatically enabled
      // during join, but not supported by TTN at this time).
      LMIC_setLinkCheckMode(0);
      digitalWrite(LedPin,LOW);
      // after Joining a job with the values will be sent.
      joined = true;
      break;
    case EV_RFU1:
      Serial.println(F("EV_RFU1"));
      break;
    case EV_JOIN_FAILED:
      Serial.println(F("EV_JOIN_FAILED"));
      break;
    case EV_REJOIN_FAILED:
      Serial.println(F("EV_REJOIN_FAILED"));
      // Re-init
      os_setCallback(&initjob, initfunc);      
      break;
    case EV_TXCOMPLETE:
      sleeping = true;
        if (LMIC.dataLen) {
        // data received in rx slot after tx
        // if any data received, a LED will blink
        // this number of times, with a maximum of 10
        Serial.print(F("Data Received: "));
        Serial.println(LMIC.frame[LMIC.dataBeg],HEX);
        i=(LMIC.frame[LMIC.dataBeg]);
        // i (0..255) can be used as data for any other application
        // like controlling a relay, showing a display message etc.
        if (i>10){
          i=10;     // maximum number of BLINKs
        }
          for(j=0;j<i;j++)
          {
            digitalWrite(LedPin,HIGH);
            delay(200);
            digitalWrite(LedPin,LOW);
            delay(400);
          }
      }
      Serial.println(F("EV_TXCOMPLETE (includes waiting for RX windows)"));
      delay(50);  // delay to complete Serial Output before Sleeping

      // Schedule next transmission
      // next transmission will take place after next wake-up cycle in main loop
      break;
    case EV_LOST_TSYNC:
      Serial.println(F("EV_LOST_TSYNC"));
      break;
    case EV_RESET:
      Serial.println(F("EV_RESET"));
      break;
    case EV_RXCOMPLETE:
      // data received in ping slot
      Serial.println(F("EV_RXCOMPLETE"));
      break;
    case EV_LINK_DEAD:
      Serial.println(F("EV_LINK_DEAD"));
      break;
    case EV_LINK_ALIVE:
      Serial.println(F("EV_LINK_ALIVE"));
      break;
    default:
      Serial.println(F("Unknown event"));
      break;
  }
}


void do_send(osjob_t* j) {
  byte buffer[2];  
  float humi,temp;
  int16_t t_value, h_value, s_value;
    si7021.getHumidity(humi);
    si7021.getTemperature(temp);
    si7021.triggerMeasurement();
    // getting sensor values
    Serial.print(F("TEMP: "));
    Serial.print(temp);
    Serial.print(F(" HUMI: "));
    Serial.print(humi);
    temp = constrain(temp,-24,40);  //temp in range -24 to 40 (64 steps)
    humi=constrain(humi,20,100);    //humi in range 20 to 100 (80 steps)
    int sensorValue = analogRead(A0); // battery voltage
  // print out the value you read:
    Serial.print(F(" Battery: "));
    Serial.println(sensorValue);
  // Vout = Vin * (R2/(R1+R2))
  // Vout = Vin * (4700/(100000+4700)), 0.135V - 3V battery
  // Vout = Vin * (10000/(100000+10000)), 0,273V - 3V battery
  // Vout = Vin * (11000/(91000+11000)), 0,323V - 3V battery
  // INTERNAL: 1.1V -> 0.001V per count
  // 3V battery -> 0.135V -> 135 (4k7 on R2)
  // 3V battery -> 0.273V -> 273 (10K on R2)
  // 3V battery -> 0.324V -> 324 (11K/91K)

        t_value=int16_t((temp*(100/6.25)+2400/6.25)); //0.0625 degree steps with offset
                                                      // no negative values
        Serial.print(F("decoded TEMP: "));
        Serial.print(t_value,HEX);
        h_value=int16_t((humi-20)/5); //5% steps, offset 20.
                Serial.print(F(" decoded HUMI: "));
        Serial.print(h_value,HEX);
        s_value=(h_value<<10) + t_value;  // putting the bits in the right place
        Serial.print(F(" decoded sent: "));
        Serial.println(s_value,HEX);
        buffer[0]=s_value&0xFF; //lower byte
        buffer[1]=s_value>>8;   //higher byte
        if (sensorValue>BatteryThreshold)
        {
          Serial.println(F("Battery OK"));
         }
         else
        {
          Serial.println(F("Battery LOW"));
          buffer[1]=buffer[1]+0x80; //warning in bit 15.
         }
        
    // Check if there is not a current TX/RX job running
  if (LMIC.opmode & OP_TXRXPEND) {
    Serial.println(F("OP_TXRXPEND, not sending"));
  } else {
    // Prepare upstream data transmission at the next possible time.
    LMIC_setTxData2(1, (uint8_t*) buffer, 2 , 0);
    Serial.println(F("Sending: "));
  }
}


// initial job
static void initfunc (osjob_t* j) {
    // reset MAC state
    LMIC_reset();
    // start joining
    LMIC_startJoining();
    // init done - onEvent() callback will be invoked...
}

void setup()
  {
  Serial.begin(115200);
  Serial.println(F("Starting"));
  Serial.print(F("Probe SI7021: "));
  if (si7021.initialize()) Serial.println(F("Sensor found!"));
    else
    {
        Serial.println(F("Sensor missing"));
        while(1) {}; // Program will stop if there is no sensor
    }
   analogReference(INTERNAL); //reference will be 1,1V internal on 3.3V Arduino
  // LED is connected to pin 10, if this port is NOT set as output before
  // SPI initialization, it will be used as SS (Slave Select) and controlled by the SPI module
      pinMode(LedPin, OUTPUT); 
  os_init();
  // Reset the MAC state. Session and pending data transfers will be discarded.
  os_setCallback(&initjob, initfunc);
  LMIC_reset();
}


void loop()
{
    // start OTAA JOIN
    if (joined==false)
    {

      os_runloop_once();
      
    }
    else
    {  
      do_send(&sendjob);    // Sent sensor values
      while(sleeping == false)
      {
        os_runloop_once();
      }
      sleeping = false;
      for (int i=0;i<sleepcycles;i++)
      {
          LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);    //sleep 8 seconds
      }
    }
      
      digitalWrite(LedPin,((millis()/100) % 2) && (joined==false)); // only blinking when joining and not sleeping
    
}