Proximity GUI - Smart Devices and Systems for Wearable Applications

thresholds, the code switches on the LED stripes in relation with the TX-RX proximity. Figure A.2 shows the GUI.

The firmware code used for the MCU is the same presented in Para-graph A.1.

MCU FREQUENCY COUNTER ANDWIFI TRANSMISSION using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Net.Sockets;

using System.Threading;

using System.Net;

public class StateObject {

// Client socket.

public Socket workSocket = null;

// Size of receive buffer.

public const int BufferSize = 256;

// Receive buffer.

public byte[] buffer = new byte[BufferSize];

// Received data string.

public StringBuilder sb = new StringBuilder();

}

public class AsynchronousClient {

// The port number for the remote device.

private const int port = 255;

// ManualResetEvent instances signal completion.

private static ManualResetEvent connectDone = new ManualResetEvent(false);

private static ManualResetEvent sendDone = new ManualResetEvent(false);

private static ManualResetEvent receiveDone = new ManualResetEvent(false);

// The response from the remote device.

private static String response = String.Empty;

public static void StartClient() {

//---//Connect to a remote device

try {

// Establish the remote endpoint for the socket.

// The name of the

// remote device is "host.contoso.com".

//IPHostEntry ipHostInfo = Dns.GetHostEntry("192.168.43.102:255");

//IPAddress ipAddress = ipHostInfo.AddressList[0];

IPAddress ipAddress = IPAddress.Parse("192.168.43.102");

IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);

// Create a TCP/IP socket.

Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

// Connect to the remote endpoint.

client.BeginConnect(remoteEP,

new AsyncCallback(ConnectCallback), client);

connectDone.WaitOne();

// Send test data to the remote device.

Send(client, "This is a test<EOF>");

sendDone.WaitOne();

// Receive the response from the remote device.

Receive(client);

receiveDone.WaitOne();

// Write the response to the console.

Console.WriteLine("Response received : {0}", response);

// Release the socket.

A.2. Appendix Chapter 3 125

Console.WriteLine(e.ToString());

} }

private static void ConnectCallback(IAsyncResult ar) {

try {

// Retrieve the socket from the state object.

Socket client = (Socket)ar.AsyncState;

// Complete the connection.

client.EndConnect(ar);

Console.WriteLine("Socket connected to {0}", client.RemoteEndPoint.ToString());

// Signal that the connection has been made.

connectDone.Set();

private static void Receive(Socket client) {

try {

// Create the state object.

StateObject state = new StateObject();

state.workSocket = client;

// Begin receiving the data from the remote device.

client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,

private static void ReceiveCallback(IAsyncResult ar) {

try {

// Retrieve the state object and the client socket // from the asynchronous state object.

StateObject state = (StateObject)ar.AsyncState;

Socket client = state.workSocket;

// Read data from the remote device.

int bytesRead = client.EndReceive(ar);

if (bytesRead > 0)

{

// There might be more data, so store the data received so far.

response = Encoding.ASCII.GetString(state.buffer, 0, bytesRead);

Console.Write("{0}", response);

// All the data has arrived; put it in response.

if (state.sb.Length > 1) {

response = state.sb.ToString();

}

// Signal that all bytes have been received.

receiveDone.Set();

static void Send(Socket client, String data) {

// Convert the string data to byte data using ASCII encoding.

byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.

client.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), client);

}

private static void SendCallback(IAsyncResult ar) {

try {

// Retrieve the socket from the state object.

Socket client = (Socket)ar.AsyncState;

A.3. Appendix Chapter 5 127

// Complete sending the data to the remote device.

int bytesSent = client.EndSend(ar);

Console.WriteLine("Sent {0} bytes to server.", bytesSent);

sendDone.Set();

The following paragraph describes in depth two firmware codes used with the ATmega32u4 for the load and stretch monitoring system respectively.

The first firmware code presented is able to read an ADC the voltage variation, due to the FSR value into the voltage divider, and to convert into a force.

Then, the firmware for the stretch monitoring system consists in a fre-quency counter, explained in Paragraph A.1, and a code for the Bluetooth communication.

LOADMONITORINGSYSTEM- ∆R − to − ∆F

//Project: Load Monitorin System with FSR //Communication: Serial port

//Author: Matteo Stoppa - Istituto Italiano di Tecnologia

//Description: FSR measurements and R-to-F convertion

//MCU: ATmega32u4

#define NUMSAMPLES 50

int fsrPin1 = 0; // the FSR and 10K pulldown are connected to a0 int fsrReading1; // the analog reading from the FSR 1 resistor divider int fsrVoltage; // the analog reading converted to voltage 1

float fsrResistance; // The voltage converted to resistance 1, //can be very big so make "long"

float fsrConductance;

float fsrForce; // Finally, the resistance converted to force 1

float average;

float samples1[NUMSAMPLES];

uint8_t i;

int LEDpin = 13;

int LEDbrightness;

void setup(void) {

Serial.begin(9600); //We’ll send debugging information //via the Serial monitor.

}

void loop(void) {

fsrReading = analogRead(fsrPin);

//Serial.print("Sensor = ");

//Serial.println(fsrReading);

// analog voltage reading ranges from about 0 to 1023 // which maps to 0V to 5V (= 5000mV)

fsrVoltage1 = map(fsrReading, 0, 1023, 0, 5000);

//Serial.print("Sensor 1 in mV = ");

//Serial.println(fsrVoltage1);

LEDbrightness = map(fsrReading, 0, 1023, 0, 255);

// LED gets brighter the harder you press analogWrite(LEDpin, LEDbrightness);

if (fsrVoltage == 0 && fsrVoltage2 == 0) { Serial.println("No pressure");

} else {

// fsrVoltage is in millivolts so 5V fsrResistance = 5000 - fsrVoltage;

// 10K resistor

fsrResistance *= 10000;

fsrResistance /= fsrVoltage;

fsrResistance /= 1000;

//Serial.print("FSR resistance in Kohms = ");

//Serial.println(fsrResistance1,5);

//Serial.println(fsrResistance);

fsrConductance = 1 / (fsrResistance);

//Serial.print("Conductance in Siemens: ");

//Serial.println(fsrConductance1,5);

//AVERAGE//

// take N samples in a row, with a slight delay average = 0;

for (i=0; i< NUMSAMPLES; i++) { samples[i] = fsrResistance;

A.3. Appendix Chapter 5 129

average += samples[i]; // average all the samples out

delay(1);

}

average /= NUMSAMPLES;

average = 0;

for (i=0; i< NUMSAMPLES; i++) { samples[i] = fsrReading;

delay(1);

}

for (i=0; i< NUMSAMPLES; i++) { average += samples[i];

}

average /= NUMSAMPLES;

Serial.println(average);

//Serial.print("FSR resistance in Kohms = ");

//Serial.println(average,5);

// Use the FSR guide graphs to approximate the force (see datasheet) if (fsrConductance <= 0.07) {

average = fsrConductance * 555,556;

//Serial.print("Force in grams Sensor1: ");