Your code is working just fine.


48 = the ascii code for the "0" character (the value you're getting from the sensor).
13 = the ascii code for carriage return
10 = the ascii code for a line feed.

You're seeing the 13 and 10 because "println" adds them to trigger a new line.  In the the arduino debug terminal you'd just see a bunch of zeros with line breaks because it will interpret the bytes as ascii characters.  In processing, the serial library will just read them as raw values which is what you're experiencing.

It sounds like the pressure sensor might not be connected/working properly if you're only seeing zeros (the 48's) though.

That depends on the resolution you need for the sensor values.

If you don't need the full 0 to 1024 range provided by the analog pin, you can use "map" to adjust the value so it's only between 0 and 255 then use Serial.print() and just send the raw byte (use BYTE instead of DEC). Then the data received by processing would directly reflect the sensor value.

Note: in the example below, the serial output from the arduino will look like nonsense if you view it in the debug terminal.

Something like this (arduino code) -
Code:

int pressurePin = 5;
int var;
 
void setup() {
    Serial.begin(9600);
    pinMode(pressurePin, INPUT);
}
 
void loop() {
    var = analogRead(pressurePin);
    var = map(var, 0, 1023, 0, 255);
    Serial.print(var, BYTE);
}
 

If you DO need the full 0 to 1024 range, you will have to send more than one byte to represent the value.  I can help with that if you need it, but if you're just getting started I would recommend you stick to the simpler way I listed here..