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Topic: WiFi Shield minus USB to Arduino/Computer Question (Read 1 time) previous topic - next topic


I just picked up the WiFi Shield from Arduino. After using the shields example code (SimpleWiFiWebServer) and combining it to some LED Strip coding, I was able to control the RGB LED Strip from a web interface.

The WiFi shield is connected to an Arduino Mega, the LED strip is connected to a 5V wall plug, and the Arduino is connected to my laptop via a USB Cable.

Its seems like I must run (load) the sketch and launch the Arduino Serial Monitor for the shield to connect to my network. Must I do this everytime? What would I need to do to sever the USB cable from the Arduino?



Here is my code:

Code: [Select]
  WiFi Web Server LED Blink

A simple web server that lets you blink an LED via the web.
This sketch will print the IP address of your WiFi Shield (once connected)
to the Serial monitor. From there, you can open that address in a web browser
to turn on and off the LED on pin 6.

If the IP address of your shield is yourAddress:
http://yourAddress/H turns the LED on
http://yourAddress/L turns it off

This example is written for a network using WPA encryption. For
WEP or WPA, change the Wifi.begin() call accordingly.

* WiFi shield attached
* LED attached to pin 6

created 25 Nov 2012
by Tom Igoe
#include <SPI.h>
#include <WiFi.h>
#include <Adafruit_NeoPixel.h>

// Parameter 1 = number of pixels in strip
// Parameter 2 = pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_RGB     Pixels are wired for RGB bitstream
//   NEO_GRB     Pixels are wired for GRB bitstream
//   NEO_KHZ400  400 KHz bitstream (e.g. FLORA pixels)
//   NEO_KHZ800  800 KHz bitstream (e.g. High Density LED strip)

Adafruit_NeoPixel strip = Adafruit_NeoPixel(120, 6, NEO_GRB + NEO_KHZ800);

char ssid[] = "EnGeniusE27B20";      //  your network SSID (name)
//char pass[] = "secretPassword";   // your network password
//int keyIndex = 0;                 // your network key Index number (needed only for WEP)

int status = WL_IDLE_STATUS;
WiFiServer server(80);

void setup() {
  strip.show(); // Initialize all pixels to 'off'
  pinMode(6, OUTPUT);      // set the LED pin mode
  Serial.begin(9600);      // initialize serial communication

  // check for the presence of the shield:
  if (WiFi.status() == WL_NO_SHIELD) {
    Serial.println("WiFi shield not present");
    while(true);        // don't continue

  // attempt to connect to Wifi network:
  while ( status != WL_CONNECTED) {
    Serial.print("Attempting to connect to Network named: ");
    Serial.println(ssid);                   // print the network name (SSID);

    // Connect to WPA/WPA2 network. Change this line if using open or WEP network:   
    status = WiFi.begin(ssid);
    // wait 5 seconds for connection:
  server.begin();                           // start the web server on port 80
  printWifiStatus();                        // you're connected now, so print out the status

void loop() {
  WiFiClient client = server.available();   // listen for incoming clients

  if (client) {                             // if you get a client,
    Serial.println("new client");           // print a message out the serial port
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected()) {            // loop while the client's connected
      if (client.available()) {             // if there's bytes to read from the client,
        char c = client.read();             // read a byte, then
        Serial.write(c);                    // print it out the serial monitor
        if (c == '\n') {                    // if the byte is a newline character

          // if the current line is blank, you got two newline characters in a row.
          // that's the end of the client HTTP request, so send a response:
          if (currentLine.length() == 0) { 
            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
            // and a content-type so the client knows what's coming, then a blank line:   
            client.println("HTTP/1.1 200 OK");

            // the content of the HTTP response follows the header:
            client.print("Click <a href=\"/H\">here</a> to run Scanner<br>");
            client.print("Click <a href=\"/L\">here</a> to run Swipe<br>");

            // The HTTP response ends with another blank line:
            // break out of the while loop:
          else {      // if you got a newline, then clear currentLine:
            currentLine = "";
        else if (c != '\r') {    // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine

        // Check to see if the client request was "GET /H" or "GET /L":
        if (currentLine.endsWith("GET /H") == 1 ) {
                    scanner(127,0,127, 10); // Violet

        //if (currentLine.endsWith("GET /H")) {
          //scanner(127,0,127, 10); // Violet
        if (currentLine.endsWith("GET /L") == 1) {
          colorFollow(strip.Color(127,0,127), 10); //Violet
    // close the connection:
    Serial.println("client disonnected");

void printWifiStatus() {
  // print the SSID of the network you're attached to:
  Serial.print("SSID: ");

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

  // print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("signal strength (RSSI):");
  Serial.println(" dBm");
  // print where to go in a browser:
  Serial.print("To see this page in action, open a browser to http://");

void colorFollow(uint32_t c, uint8_t wait) {
  for(uint16_t k=0; k<strip.numPixels()*2; k++)
      strip.setPixelColor(k, c);

// "Larson scanner" = Cylon/KITT bouncing light effect
void scanner(uint8_t r, uint8_t g, uint8_t b, uint8_t wait) {
  int i, j, pos, dir;

  pos = 0;
  dir = 1;

  for(i=0; i<((strip.numPixels()-1) * 4); i++) {
    // Draw 5 pixels centered on pos.  setPixelColor() will clip
    // any pixels off the ends of the strip, no worries there.
    // we'll make the colors dimmer at the edges for a nice pulse
    // look
    strip.setPixelColor(pos - 2, strip.Color(r/4, g/4, b/4));
    strip.setPixelColor(pos - 1, strip.Color(r/2, g/2, b/2));
    strip.setPixelColor(pos, strip.Color(r, g, b));
    strip.setPixelColor(pos + 1, strip.Color(r/2, g/2, b/2));
    strip.setPixelColor(pos + 2, strip.Color(r/4, g/4, b/4));

    // If we wanted to be sneaky we could erase just the tail end
    // pixel, but it's much easier just to erase the whole thing
    // and draw a new one next time.
    for(j=-2; j<= 2; j++)
        strip.setPixelColor(pos+j, strip.Color(0,0,0));
    // Bounce off ends of strip
    pos += dir;
    if(pos < 0) {
      pos = 1;
      dir = -dir;
    } else if(pos >= strip.numPixels()) {
      pos = strip.numPixels() - 2;
      dir = -dir;

How can I establish a connection with out a USB cable going to the Arduino from my laptop?


From http://arduino.cc/en/Guide/ArduinoWiFiShield#toc1

To use the shield, mount it on top of an Arduino board (e.g. the Uno). To upload sketches to the board, connect it to your computer with a USB cable as you normally would. Once the sketch has been uploaded, you can disconnect the board from your computer and power it with an external power supply.

As soon as I disconnect the USB cable, the webpage freezes and displays a no-connection error.

Any suggestions?


Power was the issue, I took a 9V connector and soldered it to a 2.1mm jack. I then had the LEDs powered from a 5V wall pack.

Once I ran the sketch from the Arduino IDE, I launched the Serial Monitor and waited for the device to connect.

Once connected, I unplugged the USB and the signal maintained it's link to the network.

Case solved, I wasn't supplying enough power and signal dropped.

Here is the setup:

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