Published March 23, 2016 © GPL3+

Self Sustained WiFi Sensor Node

A sensor node that publishes Temperature, Ambient Light, Humidity, Atmospheric Pressure to the cloud and does not need battery replacement.

AdvancedFull instructions provided2,398

Things used in this project

Hardware components

RedBear WiFi Micro Kit

Texas Instruments HDC1080

Texas Instruments OPT3001

Texas Instruments BQ25505

Solar Panel (2W, 5.5V)

Texas Instruments TPS63001

LiPo Battery

NXP MPL3115A2

AAA or AA Battery x 2

Story

A little while ago i got really interested in ultralow power applications and Energy Harvesting. After researching for a while i chose to do some projects that exploit energy harvesting. For my parts selection i decided to go with TI’s BQ25505 and BQ25570. I designed shields for my WiFi Micro (it uses TI's CC3200 SoC) keeping in mind that my input energy is Solar.

BQ25505 and BQ25570 are specifically designed to efficiently extract the microwatts to milliwatts of power generated from a variety of DC energy harvesting, high-impedance sources like photo-voltaic (solar) or thermal electric generators (TEGs) without collapsing those sources.

For the sensing part i decided to go with ultralow power Digital Sensors (all of them are I2C interface) so that the overall power consumed by the microcontroller and the sensor hub is reduced by a significant amount. The sensors are as follows -

HDC1080 - Texas Instruments - Humidity and Temperature Sensor

OPT3001 - Texas Instruments - Ambient Light Sensor

MPL3115A2 - Freescale - Atmospheric Pressure and Temperature Sensor

caption (optional)

I designed the energy harvesting shields for CC3200 using Eagle and got it manufactured and after that soldered everything. After that I tested it thoroughly under various scenarios and i am glad to say that it performed perfectly under all situations.

1 / 4

I have taken extensive oscilloscope measurement screen shots to show that it works as it should under various scenarios. I will upload them on my Github page after properly classifying them.

Schematics

Code

// Best code so far, works with both router and mobile phone hotspot!!. The graphing also works!!.
#include <adafruitmpl.h>
#include <HDC1050-v2.h>
#include <utils.h>
#include <OPT3001.h>
//#include <SPI.h>
#include <WiFi.h>
//#include <WiFiClient.h>
//#include <WiFiServer.h>
#include <Wire.h>
opt3001 instance;
uint32_t resultt =0;
HDC1000 mySensor;
Adafruit_MPL3115A2 baro = Adafruit_MPL3115A2();
float pascals;
float altm ;
float tempC ;
float hdctemp ;
float hdchumi ;

// your network name also called SSID
char ssid[] = "******";
// your network password
char password[] = "*******";
// your network key Index number (needed only for WEP)
int keyIndex = 0;

WiFiServer server(80);
int i = 0;
void setup() {
  Serial.begin(115200);      // initialize serial communication
  pinMode(RED_LED, OUTPUT);      // set the LED pin mode
  instance.begin();
  mySensor.begin();
  baro.begin();
  // attempt to connect to Wifi network:
  Serial.print("Attempting to connect to Network named: ");
  // print the network name (SSID);
  Serial.println(ssid);
  // Connect to WPA/WPA2 network. Change this line if using open or WEP network:
  WiFi.begin(ssid, password);
  while ( WiFi.status() != WL_CONNECTED) {
    // print dots while we wait to connect
    Serial.print(".");
    delay(300);
  }

  Serial.println("\nYou're connected to the network");
  Serial.println("Waiting for an ip address");

  while (WiFi.localIP() == INADDR_NONE) {
    // print dots while we wait for an ip addresss
    Serial.print(".");
    delay(300);
  }

  // you're connected now, so print out the status
  printWifiStatus();

  Serial.println("Starting webserver on port 80");
  server.begin();                           // start the web server on port 80
  Serial.println("Webserver started!");

}
void loop() {
  getSensorData();
//  resultt = instance.readResult();
//  //Serial.println(resultt);
//  float pascals = baro.getPressure();
//  float altm = baro.getAltitude();
//  float tempC = baro.getTemperature();
//  double hdctemp = mySensor.getTemp();
//  double hdchumi = mySensor.getHumi();

  // listen for incoming clients
  WiFiClient client = server.available();
  if (client) {
    Serial.println("new client");
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        Serial.write(c);
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html; charset=utf-8");
          //Content-Type: text/html; charset=utf-8
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println("Access-Control-Allow-Origin: *"); //comment this line if u are facing issues showing things on webpage.
          client.println();
          //client.println("<!DOCTYPE HTML>");
          //client.println("<html>");
          client.println("<html>");
          client.print("LUX:");
          client.print(resultt);
          client.print(";");
          client.print("Temperature:");
          client.print(hdctemp);
          client.print(";Humidity:");
          client.print(hdchumi);
          client.print(";");
          client.print("  ");
          client.print("Hg:");
          client.print(pascals/3377);
          client.print(";Height:");
          client.print(altm); //client.print("m ");
          client.print(";Temp:");
          client.print(tempC); //client.print("*C");
          client.println("<br>");
          client.println("</html>");
          client.println();
          break;
        }
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        }
        else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);

    // close the connection:
    client.stop();
    Serial.println("client disonnected");
  }
  i++;
}
void printWifiStatus() {
  // print the SSID of the network you're attached to:
  Serial.print("Network Name: ");
  Serial.println(WiFi.SSID());

  // print your WiFi shield's IP address:
  IPAddress ip = WiFi.localIP();
  Serial.print("IP Address: ");
  Serial.println(ip);

  // print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("signal strength (RSSI):");
  Serial.print(rssi);
  Serial.println(" dBm");
}
void getSensorData(){
  resultt = instance.readResult();
  Serial.println(resultt);
  pascals = baro.getPressure();
  Serial.println(pascals);
  altm = baro.getAltitude();
  Serial.println(altm);
  tempC = baro.getTemperature();
  Serial.println(tempC);
  hdctemp = mySensor.getTemp();
  Serial.println(hdctemp);
  hdchumi = mySensor.getHumi();
  Serial.println(hdchumi);
  //float pascals = baro.getPressure();
  // Our weather page presents pressure in Inches (Hg)
  // Use http://www.onlineconversion.com/pressure.htm for other units
  // Serial.print(pascals/3377); Serial.println(" Inches (Hg)");
  //
  // float altm = baro.getAltitude();
  // Serial.print(altm); Serial.println(" meters");
  //
  // float tempC = baro.getTemperature();
  // Serial.print(tempC); Serial.println("*C");
}

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8" >
    <title>Smoothie Chart Example</title>
    <script type="text/javascript" src="smoothie.js"></script>
    <script type="text/javascript" src="jquery.js"></script>

  </head>
  <body>

    <canvas id="mycanvas" width="1300" height="600"></canvas>

    <script type="text/javascript">
    //var smoothie = new SmoothieChart();
    //smoothie.streamTo(document.getElementById("mycanvas"));

var line1 = new TimeSeries();
var line2 = new TimeSeries();
var line3 = new TimeSeries();
var line4 = new TimeSeries();
var line5 = new TimeSeries();
setInterval(function(getRequest) {
  // Do something every 5 seconds

$.get('http://192.168.0.102/').done(function(response) {
  var a = response.split(/[;]+/);
  var b = a[0].split(/[:]+/);
  var c = a[1].split(/[:]+/);
  var d = a[2].split(/[:]+/);
  var e = a[3].split(/[:]+/);
  var f = a[4].split(/[:]+/);

  var
    x = Date.parse(new Date()+1000) ,
    y = Number.parseFloat(b[1]) ,
    z = Number.parseFloat(c[1]) ,
    g = Number.parseFloat(d[1]) ,
    h = Number.parseFloat(e[1]) ,
    i = Number.parseFloat(f[1])
    ;

    //setInterval(function() {
      line1.append(new Date().getTime(), y);
      line2.append(new Date().getTime(), z);
      line3.append(new Date().getTime(), g);
      line4.append(new Date().getTime(), h);
      line5.append(new Date().getTime(), i);
    //}, 2000);
});
}, 2000);

// Add a random value to each line every second


// Add to SmoothieChart
//smoothie.addTimeSeries(line1);
//smoothie.addTimeSeries(line2);
function myYRangeFunction(range) {
  // TODO implement your calculation using range.min and range.max
  var min = -20;
  var max = 100;
  return {min: min, max: max};
}

var smoothie = new SmoothieChart({ millisPerPixel:34, yRangeFunction:myYRangeFunction,timestampFormatter:SmoothieChart.timeFormatter, grid: { sharpLines:true, strokeStyle: 'rgb(125, 0, 0)', fillStyle: 'rgb(255, 255, 255)', lineWidth: 1, millisPerLine: 250, verticalSections: 6 } });
      smoothie.addTimeSeries(line1, { strokeStyle: 'rgb(0, 255, 0)', lineWidth: 3 });
      smoothie.addTimeSeries(line2, { strokeStyle: 'rgb(255, 0, 255)', lineWidth: 3 });
      smoothie.addTimeSeries(line3, { strokeStyle: 'rgb(249,233,34)', lineWidth: 3 });
      smoothie.addTimeSeries(line4, { strokeStyle: 'rgb(255,255,255)', lineWidth: 3 });
      smoothie.addTimeSeries(line5, { strokeStyle: 'rgb(29,171,201)', lineWidth: 3 });

smoothie.addTimeSeries(line1, {lineWidth:4,strokeStyle:'rgba(0,0,0,0.13)'});
smoothie.streamTo(document.getElementById("mycanvas"), 2000 /*delay*/);
</script>
</body>
</html>