Team Members: David Kim, Kevin Wang

Overview

The idea of this project is to have a robot drive towards a sound source. The sound source is located through triangulation, and a sound map would be printed from the IoT chip to a website. The mbed first waits for a trigger to be sent from the web server. Once this occurs, the mbed starts to listen for 2 seconds. After that time, sends a location to the web server so show the origin of the sound source, and the robot then turns and moves towards the location.

Parts List

• mbed LPC1768 board
• Adafruit SPW2430 Mems Microphone (3)

• Sparkfun TB6612FNG Dual Motor Driver Carrier

• Sparkfun ESP8266 Wifi Chip

• Sparkfun ROB-12629 Encoder Kit (2)

• Sparkfun ROB-1330 Shadowbot Chassis
• Sparkfun ROB-13302 DC motors (2)
• Rechargable 5V battery

Schematic

Video

Code

// ESP8266 Static page WEB server to control Mbed

#include "mbed.h"
#include "Motor.h"
#include "HALLFX_ENCODER.h"

Serial pc(USBTX, USBRX);
Serial esp(p28, p27); // tx, rx
LocalFileSystem local("local");               // Create the local filesystem under the name "local"


// Standard Mbed LED definitions
DigitalOut  led1(LED1);
DigitalOut  led2(LED2);
DigitalOut  led3(LED3);
DigitalOut  led4(LED4);

// some test values to show on web page
AnalogIn   Ain1(p18);
AnalogIn   Ain2(p19);

/*
char ssid[32] = "hsd";     // enter WiFi router ssid inside the quotes
char pwd [32] = "austin123"; // enter WiFi router password inside the quotes
*/
float temperature, AdcIn, Ht;
float R1=100000, R2=10000; // resistor values to give a 10:1 reduction of measured AnalogIn voltage
char Vcc[10];
char Temp[10];

// things for sending/receiving data over serial
volatile int tx_in=0;
volatile int tx_out=0;
volatile int rx_in=0;
volatile int rx_out=0;
const int buffer_size = 4095;
char tx_buffer[buffer_size+1];
char rx_buffer[buffer_size+1];
void Tx_interrupt();
void Rx_interrupt();
void send_line();
void read_line();

int DataRX;
int update;
int count;
char cmdbuff[1024];
char replybuff[4096];
char webdata[4096]; // This may need to be bigger depending on WEB browser used
char webbuff[4096];     // Currently using 1986 characters, Increase this if more web page data added
char timebuf[30];
void SendCMD(),getreply(),ReadWebData(),startserver();
void gettime(),setRTC(),gettemp(),getbattery();
char rx_line[1024];
int port        =80;  // set server port
int SERVtimeout =5;    // set server timeout in seconds in case link breaks.
struct tm t;
// manual set RTC values
int minute      =00;    // 0-59
int hour        =12;    // 2-23
int dayofmonth  =26;    // 1-31
int month       =8;     // 1-12
int year        =15;    // last 2 digits

float mic1val;
float mic2val;
float mic3val;

float mic1max = -1000.0;
float mic2max = -1000.0;
float mic3max = -1000.0;

int mic1sample;
int mic2sample;
int mic3sample;

// MOTOR DECLARATION---------------------------------------------------------

HALLFX_ENCODER EncL(p12);
HALLFX_ENCODER EncR(p13);
Motor mL(p26, p25, p24);                        // pwm, fwd, rev left motor 
Motor mR(p21, p22, p23);                        // pwm, fwd, rev right motor

// constants
float pi = 3.141592654;
//int enc_count_wheel = 384; 
int enc_count_wheel = 300;                      // encoder count for 1 wheel revolution = 48 gear ratio * 8 poles
float d_wheel = 65.0;                           // wheel diameter = 65 mm
float c_wheel = d_wheel*pi;                     // wheel circumference =~ 204.2 mm
float d_chassis = 155.0;                         // axle length = 155 mm
float c_chassis = d_chassis*pi;                 // chassis circumference =~ 486.94
int enc_count_chassis = 1831;                   // encoder count for 1 chassis revolution = c_chassis/c_wheel*384 = 1831
float mm_2_enc_count = enc_count_wheel/c_wheel; // converts mm to encoder count


float degree;
float encDistToMove;
float xCoord;
float yCoord;

uint32_t mic1Timer;
uint32_t mic2Timer;
uint32_t mic3Timer;
AnalogIn mic1(p16);
AnalogIn mic2(p17);
AnalogIn mic3(p15);
//Timer tim;
Timeout triggerTimeout;
bool triggerD = false;
bool listeningForTrigger = true;

void enableTrigger() {
    listeningForTrigger = true;
    sprintf(cmdbuff, "count,time,analog1,analog2=0,\"%s\",\"%s\",\"%s\"\r\n","N/A","N/A","here");
    SendCMD();
}

void startMics() {
    triggerD = false;
    printf("\n\rstart");
    sprintf(cmdbuff, "count,time,analog1,analog2=0,\"%s\",\"%s\",\"%s\"\r\n","N/A","N/A","here");
    SendCMD();
    mic1max = -1000.0;
    mic2max = -1000.0;
    mic3max = -1000.0;
    //tim.start();
    printf("\n\r");
    //printf("%d\n\r", tim.read_us());
    for(int i=0; i<24000; i++) {
        
        //read mic values
        mic1val = ((mic1 * 500.0)-98.0)/1.1;
        mic2val = ((mic2 * 500.0)-98.0)/1.1;
        mic3val = ((mic3 * 500.0)-98.0)/1.1;
        
        // Obtain the sample at which the maximum value occurs
        if (mic1val > mic1max){
            mic1max = mic1val;
            mic1sample = i;
            //mic1Timer = tim.read_us();
        }
        if (mic2val > mic2max){
            mic2max = mic2val;
            mic2sample = i;
            //mic2Timer = tim.read_us();
        }
        if (mic3val > mic3max){
            mic3max = mic3val;
            mic3sample = i;
            //mic3Timer = tim.read_us();
        }
    }
    printf(" mic1max %f; sample %d\n\r mic2max %f; sample %d\n\r mic3max %f; sample %d\n\r",mic1max, mic1sample,mic2max, mic2sample,mic3max, mic3sample);
    //printf("Mic 1 time: %f\n\r", mic1Timer / 1000000.0); // timer is in milliseconds
    //printf("Mic 2 time: %f\n\r", mic2Timer / 1000000.0);
    //printf("Mic 3 time: %f\n\r", mic3Timer / 1000000.0);
    //printf("End time: %f\n\r", tim.read());
    printf("\n\r");
    
    float k = 4.61; // calibration constant 
    float diff;
    
    // sound closest to mic1
    if (mic1sample <= mic2sample && mic1sample <= mic3sample){
        diff = mic2sample - mic3sample;
        // if diff < 0, sound is closer to mic 2
        degree = k*diff;
        if (degree < -60.0){
            degree = -60.0;
            }
        else if (degree > 60){
            degree = 60.0;
            }
    }
        
    // sound closest to mic2
    else if (mic2sample <= mic1sample && mic2sample <= mic3sample){
        diff = mic3sample - mic1sample;
        // if diff < 0, sound is closer to mic 3
        degree = k*diff - 120.0;
        if (degree < -180.0){
            degree = -180.0;
            }
        else if (degree > -60.0){
            degree = -60.0;
            }
    }
        
    // sound closest to mic3
    else {
        diff = mic1sample - mic2sample;
        // if diff < 0, sound is closer to mic 3
        degree = k*diff + 120.0;
            if (degree < 60.0){
            degree = 60.0;
            }
            else if (degree > 180.0){
            degree = 180.0;
            }
    }
    printf("sample diff: %f, degree: %f",diff,degree);
}

void turnMotors() {
    // coordinates (mm)
    xCoord = (500.0*cos(degree*pi/180.0));
    yCoord = (500.0*sin(degree*pi/180.0));
    printf("Start\n\r");
    printf("start motor, moving to (%f, %f)\n\r", xCoord, yCoord);
    sprintf(cmdbuff, "count,time,analog1,analog2=3,\"%f\",\"%f\",\"%s\"\r\n",xCoord/100.0,yCoord/100.0,"here");
    SendCMD();
    
    // convert coordinates to encoder counts
    float mmDistToMove = sqrt(xCoord * xCoord + yCoord * yCoord);
    encDistToMove = mmDistToMove * mm_2_enc_count;
    printf("distance (mm): %f\n\r", mmDistToMove);
    
    // convert coordiantes to heading
    float angleRadians = atan2(yCoord, xCoord);
    float angleDegrees = angleRadians*180.0/pi;
    bool CW = false;
    
    // if angle is between -180 and 0, turn CW
    if (angleDegrees < 0){
        angleDegrees = -angleDegrees;
        CW = true;
        printf("angle CW(deg): %f\n\r", angleDegrees);
    }
    // if angle is between 0 and 180, turn CCW 
    else{
        printf("angle CCW(deg): %f\n\r", angleDegrees);
    }
   
    float mmDistToTurn = angleDegrees/(360.0)*c_chassis;
    float encDistToTurn = mmDistToTurn * mm_2_enc_count;
    wait (0.25);
    
    // Turning
    
    printf("turning: %f\n\r", angleDegrees);
    
    // turn CW or CCW depending on angle
    float speedR;
    // CW
    if (CW){
        mL.speed(0.45);
        mR.speed(-0.45);
        speedR = -0.45;
        }
    // CCW    
    else{
        mL.speed(-0.45);
        mR.speed(0.45);
        speedR = 0.45;
        }
   
    int leftRead = 0;
    int rightRead = 0;
    float newspeedR = 0;
    EncL.reset();
    EncR.reset();
    
    while(leftRead + rightRead < 1.5*encDistToTurn) {
        
        // get encoder values
        leftRead = EncL.read();
        rightRead = EncR.read();
        
        // use difference to adjust motor speeds
        int diff = leftRead - rightRead;
        if (CW){
            newspeedR = speedR - float(diff / 25.0);
        }
        else{
            newspeedR = speedR + float(diff / 25.0);
        }
        if (newspeedR > 0.95){
            newspeedR = 0.95;
            }
        
        printf("%i %f\n\r",diff,newspeedR);
        mR.speed(newspeedR);
        wait(0.1);    
    }
    
    // stop motors
    mL.speed(0.2);
    mR.speed(0.2);
   
    // Reset encoders 
    EncR.reset();
    EncL.reset();
    wait(0.5);
}

void moveToDest() {
    
    // initialize speed
    mL.speed(0.8);
    mR.speed(0.8);
    
    //Encoder Reset
    EncR.reset();
    EncL.reset();
    
    int speedR = 0.8;
    int leftRead = 0;
    int rightRead = 0;
    pc.printf("\n\rmoveToDest\n\r");
    
    while(leftRead + rightRead < 2*encDistToMove) {
        
        // get encoder values
        leftRead = EncL.read();
        rightRead = EncR.read();
        
        // use difference to adjust motor speeds
        int diff = leftRead - rightRead;
        float newspeedR = speedR + float(diff / 35.0);
            if (newspeedR > 0.95){
            newspeedR = 0.95;
            }
        mR.speed(newspeedR);
        wait(0.1);      
    }
    // Encoder Reset
    EncR.reset();
    EncL.reset();
    
    // Stop motors
    mR.speed(0.2);
    mL.speed(0.2);
    
    sprintf(cmdbuff, "count,time,analog1,analog2=5,\"%s\",\"%s\",\"%s\"\r\n","N/A","N/A","here");
    SendCMD();
    triggerTimeout.attach(&enableTrigger, 5.0);
}

int main()
{
    ////////////////////////////////////////////////////
    // STEP 1: Set up IOT
    ////////////////////////////////////////////////////
    mR.speed(0.2);
    mL.speed(0.2);
    pc.baud(9600);
    esp.baud(9600);
    led1=1,led2=0,led3=0, led4=0;
    // Setup a serial interrupt function to receive data
    esp.attach(&Rx_interrupt, Serial::RxIrq);
    // Setup a serial interrupt function to transmit data
    esp.attach(&Tx_interrupt, Serial::TxIrq);
    if (time(NULL) < 1420070400) {
        setRTC();
    }
    startserver();
    DataRX=0;
    count=0;
    triggerD = false;
    
    led2 = 1;
    while(1) {
        if(DataRX==1) {
            ReadWebData();
            esp.attach(&Rx_interrupt, Serial::RxIrq);
        }
        if(update==1) // update time, hit count, and analog levels in the HUZZAH chip
        {
            // get new values
            gettime();
            gettemp();
            getbattery();
            count++;
            // send new values
            //count = rand() % 7;
            //sprintf(cmdbuff, "count,time,analog1,analog2=5,\"%s\",\"%s\",\"%s\"\r\n","5","-5","here");
            //SendCMD();
            //getreply();
            if (triggerD && listeningForTrigger) {
                listeningForTrigger = false;
                startMics();
                sprintf(cmdbuff, "count,time,analog1,analog2=2,\"%s\",\"%s\",\"%s\"\r\n","N/A","N/A","here");
                SendCMD();
                turnMotors();
                moveToDest();    
            }
            update=0;
        }
        
    }
}

// Reads and processes GET and POST web data
void ReadWebData()
{
    wait_ms(200);
    esp.attach(NULL,Serial::RxIrq);
    DataRX=0;
    memset(webdata, '\0', sizeof(webdata));
    strcpy(webdata, rx_buffer);
    memset(rx_buffer, '\0', sizeof(rx_buffer));
    rx_in = 0;
    rx_out = 0;
    pc.printf("WEBDATA_KEVIN____S\n\r");
    pc.printf(webdata);
    pc.printf("WEBDATA_KEVIN____E\n\r");
    // check web data for form information
    if( strstr(webdata, "check=led1v") != NULL ) {
        led1=!led1;
    }
    if( strstr(webdata, "check=led2v") != NULL ) {
        led2=!led2;
    }
    if( strstr(webdata, "check=led3v") != NULL ) {
        led3=!led3;
    }
    if( strstr(webdata, "check=led4v") != NULL ) {
        led4=!led4;
    }
    if( strstr(webdata, "POST") != NULL ) { // set update flag if POST request
        update=1;
        triggerD = true;
    }
    if( strstr(webdata, "GET") != NULL && strstr(webdata, "favicon") == NULL ) { // set update flag for GET request but do not want to update for favicon requests
        update=1;
    }
}
// Starts webserver
void startserver()
{
    gettime();
    gettemp();
    getbattery();
    pc.printf("++++++++++ Resetting ESP ++++++++++\r\n");
    strcpy(cmdbuff,"node.restart()\r\n");
    SendCMD();
    wait(2);
    getreply();
    
    pc.printf("\n++++++++++ Starting Server ++++++++++\r\n> ");

    // initial values
    sprintf(cmdbuff, "count,time,analog1,analog2=5,\"%s\",\"%s\",\"%s\"\r\n",timebuf,Temp,Vcc);
    SendCMD();
    getreply();
    wait(0.5);

    //create server
    sprintf(cmdbuff, "srv=net.createServer(net.TCP,%d)\r\n",SERVtimeout);
    SendCMD();
    getreply();
    wait(0.5);
    strcpy(cmdbuff,"srv:listen(80,function(conn)\r\n");
    SendCMD();
    getreply();
    wait(0.3);
        strcpy(cmdbuff,"conn:on(\"receive\",function(conn,payload) \r\n");
        SendCMD();
        getreply();
        wait(0.3);
        
        //print data to mbed
        strcpy(cmdbuff,"print(payload)\r\n");
        SendCMD();
        getreply();
        wait(0.2);
       
        //web page data
        pc.printf("Opening file..\n\r");
        FILE *fp = fopen("/local/index.txt", "r");  // Open "out.txt" on the local file system for writing
        char buffer[256];
        while(fgets(buffer, 256, fp)) {
            strcpy(cmdbuff,buffer);
            pc.printf("cmdbuff: %s\n\r", cmdbuff);
            SendCMD();
            getreply();
            wait(0.4);
        }
        fclose(fp);
        pc.printf("File closed\n\r");
        /*strcpy(cmdbuff,"conn:send('<!DOCTYPE html><html><body><h1>ESP8266 Mbed IoT Web Controller</h1>')\r\n");
        SendCMD();
        getreply();
        wait(0.4);
        strcpy(cmdbuff,"conn:send('Hit count: '..count..'')\r\n");
        SendCMD();
        getreply();
        wait(0.2);
        strcpy(cmdbuff,"conn:send('<br>Last hit (based on mbed RTC time): '..time..'<br><hr>')\r\n");
        SendCMD();
        getreply();
        wait(0.4);
        strcpy(cmdbuff,"conn:send('Analog 1: '..analog1..' V<br>Analog 2: '..analog2..' V<br><hr>')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff,"conn:send('<form method=\"POST\"')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff, "conn:send('<p><input type=\"checkbox\" name=\"check\" value=\"led1v\"> flip LED1')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff, "conn:send('<p><input type=\"text\" name=\"check\" value=\"led2v\"> flip LED2')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff, "conn:send('<p><input type=\"checkbox\" name=\"check\" value=\"led3v\"> flip LED3')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff, "conn:send('<p><input type=\"checkbox\" name=\"check\" value=\"led4v\"> flip LED4')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff,"conn:send('<p><input type=\"submit\" value=\"send-refresh\"></form>')\r\n");
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff, "conn:send('<p><h2>How to use:</h2><ul><li>Select a checkbox to flip on/off</li><li>Click Send-Refresh to send data and refresh values</li></ul></body></html>')\r\n");
        SendCMD();
        getreply();
        wait(0.5); */
        // end web page data
        strcpy(cmdbuff, "conn:on(\"sent\",function(conn) conn:close() end)\r\n"); // close current connection
        SendCMD();
        getreply();
        wait(0.3);
        strcpy(cmdbuff, "end)\r\n");
        SendCMD();
        getreply();
        wait(0.2);
    strcpy(cmdbuff, "end)\r\n");
    SendCMD();
    getreply();
    wait(0.2);

    strcpy(cmdbuff, "tmr.alarm(0, 1000, 1, function()\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff, "if wifi.sta.getip() == nil then\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff, "print(\"Connecting to AP...\\n\")\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff, "else\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff, "ip, nm, gw=wifi.sta.getip()\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff,"print(\"IP Address: \",ip)\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff,"tmr.stop(0)\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff,"end\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    strcpy(cmdbuff,"end)\r\n");
    SendCMD();
    getreply();
    wait(0.2);
    
    pc.printf("\n\n++++++++++ Ready ++++++++++\r\n\n");
}


// ESP Command data send
void SendCMD()
{
    int i;
    char temp_char;
    bool empty;
    i = 0;
// Start Critical Section - don't interrupt while changing global buffer variables
    NVIC_DisableIRQ(UART1_IRQn);
    empty = (tx_in == tx_out);
    while ((i==0) || (cmdbuff[i-1] != '\n')) {
// Wait if buffer full
        if (((tx_in + 1) % buffer_size) == tx_out) {
// End Critical Section - need to let interrupt routine empty buffer by sending
            NVIC_EnableIRQ(UART1_IRQn);
            while (((tx_in + 1) % buffer_size) == tx_out) {
            }
// Start Critical Section - don't interrupt while changing global buffer variables
            NVIC_DisableIRQ(UART1_IRQn);
        }
        tx_buffer[tx_in] = cmdbuff[i];
        i++;
        tx_in = (tx_in + 1) % buffer_size;
    }
    if (esp.writeable() && (empty)) {
        temp_char = tx_buffer[tx_out];
        tx_out = (tx_out + 1) % buffer_size;
// Send first character to start tx interrupts, if stopped
        esp.putc(temp_char);
    }
// End Critical Section
    NVIC_EnableIRQ(UART1_IRQn);
    return;
}

// Get Command and ESP status replies
void getreply()
{
    read_line();
    sscanf(rx_line,replybuff);
}
 
// Read a line from the large rx buffer from rx interrupt routine
void read_line() {
    int i;
    i = 0;
// Start Critical Section - don't interrupt while changing global buffer variables
    NVIC_DisableIRQ(UART1_IRQn);
// Loop reading rx buffer characters until end of line character
    while ((i==0) || (rx_line[i-1] != '\r')) {
// Wait if buffer empty
        if (rx_in == rx_out) {
// End Critical Section - need to allow rx interrupt to get new characters for buffer
            NVIC_EnableIRQ(UART1_IRQn);
            while (rx_in == rx_out) {
            }
// Start Critical Section - don't interrupt while changing global buffer variables
            NVIC_DisableIRQ(UART1_IRQn);
        }
        rx_line[i] = rx_buffer[rx_out];
        i++;
        rx_out = (rx_out + 1) % buffer_size;
    }
// End Critical Section
    NVIC_EnableIRQ(UART1_IRQn);
    rx_line[i-1] = 0;
    return;
}
 
 
// Interupt Routine to read in data from serial port
void Rx_interrupt() {
    DataRX=1;
    //led3=1;
// Loop just in case more than one character is in UART's receive FIFO buffer
// Stop if buffer full
    while ((esp.readable()) && (((rx_in + 1) % buffer_size) != rx_out)) {
        rx_buffer[rx_in] = esp.getc();
// Uncomment to Echo to USB serial to watch data flow
        pc.putc(rx_buffer[rx_in]);
        rx_in = (rx_in + 1) % buffer_size;
    }
    //led3=0;
    return;
}
 
 
// Interupt Routine to write out data to serial port
void Tx_interrupt() {
    //led2=1;
// Loop to fill more than one character in UART's transmit FIFO buffer
// Stop if buffer empty
    while ((esp.writeable()) && (tx_in != tx_out)) {
        esp.putc(tx_buffer[tx_out]);
        tx_out = (tx_out + 1) % buffer_size;
    }
    //led2=0;
    return;
}

void gettime()
{
    time_t seconds = time(NULL);
    strftime(timebuf,50,"%H:%M:%S %a %d %b %y", localtime(&seconds));
}

void setRTC()
{
    t.tm_sec = (0);             // 0-59
    t.tm_min = (minute);        // 0-59
    t.tm_hour = (hour);         // 0-23
    t.tm_mday = (dayofmonth);   // 1-31
    t.tm_mon = (month-1);       // 0-11  "0" = Jan, -1 added for Mbed RCT clock format
    t.tm_year = ((year)+100);   // year since 1900,  current DCF year + 100 + 1900 = correct year
    set_time(mktime(&t));       // set RTC clock
}
// Analog in example
void getbattery()
{
    AdcIn=Ain1.read();
    Ht = (AdcIn*3.3); // set the numeric to the exact MCU analog reference voltage for greater accuracy
    sprintf(Vcc,"%2.3f",Ht);
}
// Temperature example
void gettemp()
{
 
    AdcIn=Ain2.read();
    Ht = (AdcIn*3.3); // set the numeric to the exact MCU analog reference voltage for greater accuracy  
    sprintf(Temp,"%2.3f",Ht);
}

Have this labeled as index.txt in the mbed local file system. IoT chip should be configured to a network prior to running the code.

conn:send('<!DOCTYPE html>')

conn:send('<html>')

conn:send('<head>')

conn:send('<title>ECE 4180 - Blind Dog</title>')

conn:send('</head>')

conn:send('<body>')

conn:send('<style>')

conn:send('h3 { visibility: hidden; }')

conn:send('</style>')

conn:send('<h1>ECE 4180 - Blind Dog</h1>')
conn:send('<h3>Status code: <p id="inStat">'..count..'</p></h3>')
conn:send('<br>X coord: <p id="x">'..time..'</p><br><hr>')
conn:send('Y coord: <p id="y">'..analog1..'</p><br><h3>Analog 2: '..analog2..' V</h3><br><hr>')

conn:send('')

conn:send('<h2>Status:</h2>')

conn:send('<h2 id="status">Waiting for trigger...</h2>')

conn:send('<form method="POST">')

conn:send('<button id="button">GO!</button>')

conn:send('</form>')

conn:send('<canvas id="myCanvas" width="600" height="400" style="border:1px solid #000000;">')

conn:send('</canvas>')

conn:send('</body>')
conn:send('<script src="http://yourjavascript.com/30312385242/script.js"></script>')

conn:send('</html>')