I am trying to figure out the last two examples in the book Getting Started with Arduino by Forest Mims
I just started chapter 6/Talking to the Cloud, and have run into a problem. Which gives an example of processing and Arduino talking to each other.
The problem I have run into is located in the processing sketch which I tried to make glow red, and bold on the code for quick reference and also quoted below
URL url = new URL(feed); // An object to represent the URL
- the problem when I upload the sketch on processor it says
cannot find a class or type named "URL"
- What does this mean? Can someone help me fix it?
The code for the processing sketch is located here
http://cdn.makezine.com/make/books/getstartedarduino/eg/Example_08A.txt
For convenience, I have posted this code below
// Example 08A: Arduino networked lamp
// parts of the code are inspired
// by a blog post by Tod E. Kurt (todbot.com)
//
// Copy and paste this example into an empty Processing sketch
import processing.serial.*;
String feed = "http://blog.makezine.com/index.xml";
int interval = 10; // retrieve feed every 60 seconds;
int lastTime; // the last time we fetched the content
int love = 0;
int peace = 0;
int arduino = 0;
int light = 0; // light level measured by the lamp
Serial port;
color c;
String cs;
String buffer = ""; // Accumulates characters coming from Arduino
PFont font;
void setup() {
size(640,480);
frameRate(10); // we don't need fast updates
font = loadFont("HelveticaNeue-Bold-32.vlw");
fill(255);
textFont(font, 32);
// IMPORTANT NOTE:
// The first serial port retrieved by Serial.list()
// should be your Arduino. If not, uncomment the next
// line by deleting the // before it, and re-run the
// sketch to see a list of serial ports. Then, change
// the 0 in between [ and ] to the number of the port
// that your Arduino is connected to.
//println(Serial.list());
String arduinoPort = Serial.list()[0];
port = new Serial(this, arduinoPort, 9600); // connect to Arduino
lastTime = 0;
fetchData();
}
void draw() {
background( c );
int n = (interval - ((millis()-lastTime)/1000));
// Build a colour based on the 3 values
c = color(peace, love, arduino);
cs = "#" + hex(c,6); // Prepare a string to be sent to Arduino
text("Arduino Networked Lamp", 10,40);
text("Reading feed:", 10, 100);
text(feed, 10, 140);
text("Next update in "+ n + " seconds",10,450);
text("peace" ,10,200);
text(" " + peace, 130, 200);
rect(200,172, peace, 28);
text("love ",10,240);
text(" " + love, 130, 240);
rect(200,212, love, 28);
text("arduino ",10,280);
text(" " + arduino, 130, 280);
rect(200,252, arduino, 28);
// write the colour string to the screen
text("sending", 10, 340);
text(cs, 200,340);
text("light level", 10, 380);
rect(200, 352,light/10.23,28); // this turns 1023 into 100
if (n <= 0) {
fetchData();
lastTime = millis();
}
port.write(cs); // send data to Arduino
if (port.available() > 0) { // check if there is data waiting
int inByte = port.read(); // read one byte
if (inByte != 10) { // if byte is not newline
buffer = buffer + char(inByte); // just add it to the buffer
}
else {
// newline reached, let's process the data
if (buffer.length() > 1) { // make sure there is enough data
// chop off the last character, it's a carriage return
// (a carriage return is the character at the end of a
// line of text)
buffer = buffer.substring(0,buffer.length() -1);
// turn the buffer from string into an integer number
light = int(buffer);
// clean the buffer for the next read cycle
buffer = "";
// We're likely falling behind in taking readings
// from Arduino. So let's clear the backlog of
// incoming sensor readings so the next reading is
// up-to-date.
port.clear();
}
}
}
}
void fetchData() {
// we use these strings to parse the feed
String data;
String chunk;
// zero the counters
love = 0;
peace = 0;
arduino = 0;
try {
[b][glow=red,2,300]URL url = new URL(feed); // An object to represent the URL [/glow][/b]
// prepare a connection
URLConnection conn = url.openConnection();
conn.connect(); // now connect to the Website
// this is a bit of virtual plumbing as we connect
// the data coming from the connection to a buffered
// reader that reads the data one line at a time.
BufferedReader in = new
BufferedReader(new InputStreamReader(conn.getInputStream()));
// read each line from the feed
while ((data = in.readLine()) != null) {
StringTokenizer st =
new StringTokenizer(data,"\"<>,.()[] ");// break it down
while (st.hasMoreTokens()) {
// each chunk of data is made lowercase
chunk= st.nextToken().toLowerCase() ;
if (chunk.indexOf("love") >= 0 ) // found "love"?
love++; // increment love by 1
if (chunk.indexOf("peace") >= 0) // found "peace"?
peace++; // increment peace by 1
if (chunk.indexOf("arduino") >= 0) // found "arduino"?
arduino++; // increment arduino by 1
}
}
// Set 64 to be the maximum number of references we care about.
if (peace > 64) peace = 64;
if (love > 64) love = 64;
if (arduino > 64) arduino = 64;
peace = peace * 4; // multiply by 4 so that the max is 255,
love = love * 4; // which comes in handy when building a
arduino = arduino * 4; // colour that is made of 4 bytes (ARGB)
}
catch (Exception ex) { // If there was an error, stop the sketch
ex.printStackTrace();
System.out.println("ERROR: "+ex.getMessage());
}
}
The code for the arduino is located here http://cdn.makezine.com/make/books/getstartedarduino/eg/Example_08B.txt
and as I did previously, I copied the code below for convenience.
// Example 08B: Arduino Networked Lamp
//
// Copy and paste this example into an empty Arduino sketch
#define SENSOR 0
#define R_LED 9
#define G_LED 10
#define B_LED 11
#define BUTTON 12
int val = 0; // variable to store the value coming from the sensor
int btn = LOW;
int old_btn = LOW;
int state = 0;
char buffer[7] ;
int pointer = 0;
byte inByte = 0;
byte r = 0;
byte g = 0;
byte b = 0;
void setup() {
Serial.begin(9600); // open the serial port
pinMode(BUTTON, INPUT);
}
void loop() {
val = analogRead(SENSOR); // read the value from the sensor
Serial.println(val); // print the value to
// the serial port
if (Serial.available() >0) {
// read the incoming byte:
inByte = Serial.read();
// If the marker's found, next 6 characters are the colour
if (inByte == '#') {
while (pointer < 6) { // accumulate 6 chars
buffer[pointer] = Serial.read(); // store in the buffer
pointer++; // move the pointer forward by 1
}
// now we have the 3 numbers stored as hex numbers
// we need to decode them into 3 bytes r, g and b
r = hex2dec(buffer[1]) + hex2dec(buffer[0]) * 16;
g = hex2dec(buffer[3]) + hex2dec(buffer[2]) * 16;
b = hex2dec(buffer[5]) + hex2dec(buffer[4]) * 16;
pointer = 0; // reset the pointer so we can reuse the buffer
}
}
btn = digitalRead(BUTTON); // read input value and store it
// Check if there was a transition
if ((btn == HIGH) && (old_btn == LOW)){
state = 1 - state;
}
old_btn = btn; // val is now old, let's store it
if (state == 1) { // if the lamp is on
analogWrite(R_LED, r); // turn the leds on
analogWrite(G_LED, g); // at the colour
analogWrite(B_LED, b); // sent by the computer
} else {
analogWrite(R_LED, 0); // otherwise turn off
analogWrite(G_LED, 0);
analogWrite(B_LED, 0);
}
delay(100); // wait 100ms between each send
}
int hex2dec(byte c) { // converts one HEX character into a number
if (c >= '0' && c <= '9') {
return c - '0';
} else if (c >= 'A' && c <= 'F') {
return c - 'A' + 10;
}
}