Light flashes more times than it's asked to - arduino

Question

I am trying to get my LED to flash when the hypotenuse enters certain range. But it seems like it's passing that value of hypotenuse range more times than it should. LED Flashes for about good 30 -40 times before it goes back to being normal. Not sure how to fix this problem.
This is my processing code:
import processing.serial.*;
float r_height; // rise of the slope
float r_width; // run of the slope
float hypotnuse; // hypotenuse of the right angle
int d = 20; // diameter of the chocolate
float x ; // x of the chocolate destination
float y ; // y of the chocolate destination
int ledGlow; // how much the LED will glow
Serial myPort; // serial port object
void setup () {
size (510, 510); // size of the canvas
String portName = Serial.list()[8]; // my arduino port
myPort = new Serial(this, portName, 9600);
background (0); // color of the background
fill(204); // fill of the ellipse
ellipseMode (CORNER); //Ellipse mode
x = 0; //The placement on initial X for chocolate
y = 0; // the placement on initial Y for chocolate
ellipse (x, y, d, d); // ellipse
frameRate (30);
}
void draw () {
r_height = mouseY - y; // rise
r_width = mouseX - x; //run
hypotnuse = sqrt (( (sq(r_height)) + (sq (r_width)))); //A^2 +B^2 = C^2
ledGlow = 255 - (round (hypotnuse/2.84)); // flipping the values
myPort.write(ledGlow); // The value being sent to the Arduino
println (ledGlow);
}
This is the arduino code:
float val; // Data received from the serial port
int ledPin = 9;
void setup() {
pinMode(ledPin, OUTPUT); // Set pin as OUTPUT
Serial.begin(9600); // Start serial communication at 9600 bps
}
void loop() {
if (Serial.available())
{ // If data is available to read,
val = Serial.read(); // read it and store it in val
// long steps2move = val.toInt();
}
if (val > 230) {
analogWrite (ledPin, 255) ; // I have already tried digitalWrite
delay (100);
analogWrite (ledPin, 1) ;
delay (100);
}
else if (val < 230) {
analogWrite(ledPin, val);
}
}
UPDATED ARDUINO:
float val; // Data received from the serial port
int ledPin = 9; // Set the pin to digital I/O 13
unsigned long currentTime = 0;
unsigned long pastTime = 0;
int currentState = 0;
int wait = 0;
void setup() {
pinMode(ledPin, OUTPUT); // Set pin as OUTPUT
Serial.begin(9600); // Start serial communication at 9600 bps
}
void loop() {
if (Serial.available())
{ // If data is available to read,
val = Serial.read(); // read it and store it in val
// long steps2move = val.toInt();
}
if (val > 230) {
pastTime = currentTime;
currentTime = millis();
unsigned long timePassed = currentTime - pastTime;
if(timePassed >= wait)
{
switch(currentState )
{
case 0:
digitalWrite(9, HIGH);
wait = 500;
currentState = 1;
break;
case 1:
digitalWrite(9, LOW);
wait = 500;
currentState = 0;
break;
}
}
}
else if (val < 230) {
analogWrite(ledPin, val/2);
}
}

Answer 1

The processing code is presumably writing out to serial constantly. However, when the hypotenuse enters the range you've set, the Arduino has those delay() calls. I think that will be causing it to lag behind, so it keeps flashing while it clears the backlog of serial data that came in during the delays.
I think a better approach is to avoid using delay() at all, so the Arduino can handle the serial data as fast as possible. On each loop, it should first grab the latest serial data (if there is any). Based on that, it should figure out and store what the LED should currently be doing (i.e. whether it should be flashing, or else what brightness it should be).
After that (regardless of whether any serial data was actually received), the LED can be updated from the stored state. Remember not to use delay() for the flashing though. Instead, you could keep track of the last time it flashed on, and figure out if 100 ms has passed since then (using millis()). If so, switch it off. If another 100 ms has passed, switch it back on.
This approach decouples the flash timing from the serial data, so hopefully it should work better.