hello i'm a newbie...any one can help me i wanna make water level sensor using srf04 and arduino uno...but i have a problem in processing program...i wanna read output from sensor and send data from processing to arduino to limit the water level.... thanks 
i wanna read output from sensor
It would be better to have the Arduino do that.
and send data from processing to arduino
What data?
to limit the water level
A ping type sensor can not limit the water level. Shutting off a valve, maybe...
PaulS:
It would be better to have the Arduino do that.
What data?
A ping type sensor can not limit the water level. Shutting off a valve, maybe...
yeah i wanna limit the water level or turn off the valve... but i have a problem with processing program...
i can't send float or int value... for example like 1.5 or 2.0 or 3.2 an etc
do you have a suggestion?? thanks before 
PaulS:
.
What data?
data is the distance from sensor to water .....
i can't send float or int value.
Why not? Everyone else can. Where IS your code?
PaulS:
Why not? Everyone else can. Where IS your code?
my arduino code :
char val; // Data received from the serial port
int ledPin = 4; // Set the pin to digital I/O 4
int ledPin0 = 7;
void setup() {
pinMode(ledPin, OUTPUT);
pinMode(ledPin0, OUTPUT); // Set pin as OUTPUT
Serial.begin(9600); // Start serial communication at 9600 bps
}
void loop() {
while (Serial.available()) { // If data is available to read,
val = Serial.read(); // read it and store it in val
}
if (val == '1') { // If H was received
digitalWrite(ledPin, LOW);
digitalWrite(ledPin0, LOW);// turn the LED on
Serial.print("hurung");
Serial.print("\n");
} else {
digitalWrite(ledPin, HIGH);
digitalWrite(ledPin0, HIGH); // Otherwise turn it OFF
//Serial.print("parem");
Serial.print(val);
Serial.print("\n");
}
delay(100); // Wait 100 milliseconds for next reading
}
and the processing code :
import processing.serial.*;
ButtonA ok_button;// the button
ButtonB reset_button;
int clk = 1; // number of times the button is clicked
Serial myPort; // Create object from Serial class
String val; // Data received from the serial port
String a=" ";
void setup() {
size (600, 350);
smooth();
// I know that the first port in the serial list on my mac
// is always my FTDI adaptor, so I open Serial.list()[0].
// On Windows machines, this generally opens COM1.
// Open whatever port is the one you're using.
String portName = Serial.list()[0];
myPort = new Serial(this, portName, 9600);
myPort.bufferUntil('\n');
// create the button object
ok_button = new ButtonA("OK", 20, 20, 100, 50);
reset_button = new ButtonB("Reset", 20, 80, 100, 50);
}
void draw() {
background(0);
textSize(14);
fill(255, 255, 255, 255);
textAlign(LEFT);
text("Masukan Daya Tampung = "+ a + " Liter", 20, 160);//untuk mengatur koordinat text
text(val ,20,180);
// draw a square if the mouse curser is over the button
if (ok_button.MouseIsOver()) {
rect(20, 20, 100, 50);
}
else if (reset_button.MouseIsOver()){
rect(20, 80, 100, 50);
}
else{
// hide the square if the mouse cursor is not over the button
}
// draw the button in the window
ok_button.Draw();
reset_button.Draw();
}
void serialEvent (Serial myPort){
val = myPort.readStringUntil('\n');
if(val != null){
val=trim(val);
}
}
void keyPressed(){
if( key >= '0' && key <= '9' ){
a+=str(key);
}
}
//perintah if untuk mengecek apakah tombol di tekan atau tidak
void mousePressed()
{
if (ok_button.MouseIsOver()) {
// perintah untuk mencetak jika tombol di klik
myPort.write(a);
//myPort.write("\n");
a=" ";
}
else if (reset_button.MouseIsOver()) {// If mouse is not over square,
myPort.write('H'); // send an L otherwise
//print("no click");
a=" ";
}
}
// the Button class
class ButtonA {
String label; // label tombol
float x; // kordinat x tombol
float y; // top left corner y position
float w; // variable untuk lebar tobol
float h; // variable untuk tinggi tombol
// constructor
ButtonA(String labelA, float xpos, float ypos, float widthA, float heightA) {
label = labelA;
x = xpos;
y = ypos;
w = widthA;
h = heightA;
}
void Draw() {
fill(218);
stroke(141);
rect(x, y, w, h, 10);
textAlign(CENTER, CENTER);
fill(0);
text(label, x + (w / 2), y + (h / 2));
}
boolean MouseIsOver() {
if (mouseX > x && mouseX < (x + w) && mouseY > y && mouseY < (y + h)) {
return true;
}
return false;
}
}
class ButtonB {
String label; // label tombol
float x; // top left corner x position
float y; // top left corner y position
float w; // variable untuk lebar tobol
float h; // variable untuk tinggi tombol
// constructor
ButtonB(String labelB, float xpos, float ypos, float widthB, float heightB) {
label = labelB;
x = xpos;
y = ypos;
w = widthB;
h = heightB;
}
void Draw() {
fill(218);
stroke(141);
rect(x, y, w, h, 10);
textAlign(CENTER, CENTER);
fill(0);
text(label, x + (w / 2), y + (h / 2));
}
boolean MouseIsOver() {
if (mouseX > x && mouseX < (x + w) && mouseY > y && mouseY < (y + h)) {
return true;
}
return false;
}
}
first I try to make the led on before I try ultrasonic sensor... if i type 1 char the led can turn on... but if I type 2 char in processing it not work... I very confused...confuse about send serial from processing to arduino with 2 digit number ..
for example : 20 or 10 and etc...
thanks before my friend...sori if my grammer so bad...
while (Serial.available()) { // If data is available to read,
val = Serial.read(); // read it and store it in val
}
If Processing sends "20", what will be in val, when the while loop ends?
PaulS:
while (Serial.available()) { // If data is available to read,
val = Serial.read(); // read it and store it in val
}
If Processing sends "20", what will be in val, when the while loop ends?
big thanks very very much paul.... my problem is solved... thank