I bought a WiFly a while back but didn’t really do much with it. For those of you not in the know, a WiFly is a compact wireless device that you can buy on a little break-out board… or in this case, on an Arduino Shield.
The interface to the WiFly is pretty straight forward. You initialize the library then create a Client object. This Client object has typical filehandle-like methods such as read(), available(), println() etc.
In this example, I took my previous setup with 8-bit latches and used the LEDs to display output that I submitted to a webservice using the WiFly. The Webservice in question is a very simple php app that returns a single 8-bit hex number. Here’s the code:
<?php print '@'.dechex(time() % 255); ?>
The prepended ‘@’ sign is a flag value. Because read() returns just a single char, I wanted to skip through all of the http header information to the data. I stop when I encounter the first ‘@’.
I modified the latch setup I had by using two triplets of pins instead of sharing the single triple. This allowed me to independently control two latches. Here’s the final code for the project:
#include "WiFly.h"
int latchPin1 = 2;
int clockPin1 = 3;
int dataPin1 = 4;
int latchPin2 = 5;
int clockPin2 = 6;
int dataPin2 = 7;
Client client("www.tokyo3.com", 80);
void setup() {
Serial.begin(9600);
pinMode(latchPin1, OUTPUT);
pinMode(clockPin1, OUTPUT);
pinMode(dataPin1, OUTPUT);
pinMode(latchPin2, OUTPUT);
pinMode(clockPin2, OUTPUT);
pinMode(dataPin2, OUTPUT);
WiFly.begin();
if (!WiFly.join("ssid", "password")) {
Serial.println("Association failed.");
while (1) {
// Hang on failure.
}
}
}
int convert(char ch) {
if (ch >= '0' && ch <= '9') {
return ch - '0';
}
if (ch >= 'a' && ch <= 'f') {
return ch - 'a' + 10;
}
return 0;
}
int getWebValue() {
if (!client.connected()) {
Serial.println("Connecting...");
if (!client.connect()) {
return 0;
}
}
client.println("GET /arduino.php HTTP/1.1");
client.println("Host: www.tokyo3.com");
client.println();
char ch;
while (client.available()) {
ch = client.read();
Serial.print(ch);
if (ch == '@') {
break;
}
}
if (!client.available()) {
return 0;
}
int a = convert(client.read());
int b = convert(client.read());
return (a << 4) + b;
}
int count = 0;
void loop() {
int a = getWebValue();
if (count++ % 2 == 0) {
digitalWrite(latchPin1, LOW);
shiftOut(dataPin1, clockPin1, MSBFIRST, a);
digitalWrite(latchPin1, HIGH);
} else {
digitalWrite(latchPin2, LOW);
shiftOut(dataPin2, clockPin2, MSBFIRST, a);
digitalWrite(latchPin2, HIGH);
}
delay(1000);
}
Pretty simple for the most part. As with the WiFly examples, I use the Serial Monitor to echo print. Very useful when trying to figure out what you’re getting via network.
