Photon IoT Gateway

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
#include <OneWire.h>

extern "C" {
  #include "user_interface.h"
}

//#define  DEBUG_SERIAL

// The arbitrary name for this device
#define DEVICE_NAME       "iot"

// Wifi network name
#define WIFI_SSID         "MyNetwork"

// Wifi network password
#define WIFI_PASS         "p455w0rd"

// UDP port to broadcast on
#define BROADCAST_PORT     9877

// UDP IP address to broadcast to
#define BROADCAST_ADDRESS "255.255.255.255"

// External "status" LED
#define LED_PIN            14

// How long to sleep
#define SLEEP_DURATION     55

// How long to wait (in seconds) before going back to sleep
#define POST_DATA_DELAY    1

bool statusLED = false;
uint16_t timeToConnect = 0;

char packetBuffer[UDP_TX_PACKET_MAX_SIZE];

OneWire ds(5);

WiFiUDP udp;

float t = 185;

void setup() {
#ifdef DEBUG_SERIAL
  Serial.begin(115200);
  Serial.println("");
  Serial.println("BEGIN");
#endif
  timeToConnect = millis();
  
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, HIGH);
  
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  
  udp.begin(BROADCAST_PORT);
}

void loop() {
  readSensors();
  sendData();
}


void readSensors() {
  // Loop until we get a reasonable value
  while(t>150) {
    t = getTempF();
    delay(50);
  }
}


void sendData() {
  digitalWrite(LED_PIN, LOW);
  
  // Connect to the wifi network
  if(connect()) {
    // Assemble the UDP packet
    udp.beginPacket(BROADCAST_ADDRESS, BROADCAST_PORT);
    
    String str = String(DEVICE_NAME)+";f:"+String(t, 2)+"|g,conn:"+String(millis()-timeToConnect)+"|g";
    
    str += ";"+checksum(str);
    
    char data[str.length()];
    str.toCharArray(data, str.length()+1);
        
  #ifdef DEBUG_SERIAL
    Serial.print("> ");
    Serial.print(str.length()+1);
    Serial.print(": ");
    Serial.println(data);
  #endif
    
    // Send the packet!
    udp.write(data, str.length());
    udp.endPacket();
    
    // Wait for things to settle down
    delay(POST_DATA_DELAY*1000);
    
    // Disconnect from wifi
    WiFi.disconnect();
    
    digitalWrite(LED_PIN, HIGH);
    
#ifdef DEBUG_SERIAL
    Serial.print("Sleeping for ");
    Serial.println(SLEEP_DURATION);
#endif
    
    // Go to sleep!
    system_deep_sleep_set_option(0);
    system_deep_sleep(SLEEP_DURATION * 1000000);
  }

  digitalWrite(LED_PIN, HIGH);
}


float getTempC() {
  byte data[12];
  byte addr[8];
  
  if(!ds.search(addr)) {
    ds.reset_search();
    return -1000;
  }
  
  if(OneWire::crc8(addr, 7)!=addr[7]) {
#ifdef DEBUG_SERIAL
    Serial.println("CRC is not valid!");
#endif
    return -1000;
  }
  
  if(addr[0] != 0x10 && addr[0] != 0x28) {
#ifdef DEBUG_SERIAL
    Serial.println("Device is not recognized");
#endif
    return -1000;
  }
  
  ds.reset();
  ds.select(addr);
  ds.write(0x44, 1);
  
  byte present = ds.reset();
  ds.select(addr);
  ds.write(0xBE);
  
  for(uint8_t i=0; i<9; i++) {
    data[i] = ds.read();
  }
  
  ds.reset_search();
  
  byte MSB = data[1];
  byte LSB = data[0];
  
  float tempRead = ((MSB<<8) | LSB);
  return tempRead/16;
}


float getTempF() {
  return getTempC() * 9/5 + 32;
}


uint8_t ord(char b) {
  uint8_t a;
  a = b-'0';
  return a;
}


String checksum(String s) {
  uint16_t crc = 0;
  
  for(uint8_t i=0; i<s.length(); i++) {
    crc += ord(s.charAt(i));
  }
  
  return String(crc, HEX);
}


bool connect() {
 #ifdef DEBUG_SERIAL
   Serial.print("Connecting: ");
 #endif
 
  while(WiFi.status() != WL_CONNECTED) {
    if(millis()%100==0) {
#ifdef DEBUG_SERIAL
      Serial.print(".");
#endif
      statusLED = !statusLED;
      digitalWrite(LED_PIN, statusLED);
      delay(1);
    }
  }
  
#ifdef DEBUG_SERIAL
  Serial.println(" done!");
#endif

  return true;
}