Real Time Bar Charts in arduino

Question

I have written a test program to see that my pressure sensor is working correctly and it does.

int redpin = 10;
int greenpin = 9;
int bluepin = 8;
int presurepin = 0;

//Program variables
int time = 100;
int presure = 0;
int thresholddown = 19;
int thresholdup = 52;
int color = 0;
int red   = 0;
int green = 0;
int blue  = 0;
int relesepresure = 1;

void setup() {
  pinMode(redpin, OUTPUT);
  pinMode(greenpin, OUTPUT);
  pinMode(bluepin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Read presure
  presure = analogRead(presurepin);

  // For bug finding purpose
  delay(time);
  Serial.print(presure);
  Serial.print("   ");
  Serial.println(color);

  // High presure = 0 low = 300-500
  // If high presure change color and wait until presure is low to send out the color
  if (presure < thresholddown && relesepresure == 1){
    if (color == 0){
          red   = 0;
          green = 0;
          blue  = 0;
          color = color + 1;
    }
    else if (color == 1) {
          red   = 1;
          green = 0;
          blue  = 0;
          color = color + 1;
    }
    else if (color == 2) {
          red   = 0;
          green = 1;
          blue  = 0;
          color = color + 1;
    }
    else if (color == 3) {
          red   = 0;
          green = 0;
          blue  = 1;
          color = color + 1;
    }
    else if (color == 4) {
          // Yellow
          red   = 1;
          green = 1;
          blue  = 0;
          color = 1;

    }
    // Turn of light while tile is presured
    digitalWrite(redpin,   0);   // Write current values to LED pins
    digitalWrite(greenpin, 0);
    digitalWrite(bluepin,  0);
    relesepresure = 0;
  }
  else if (presure > thresholdup && relesepresure == 0){
      //Send color to tile
      digitalWrite(redpin,   red);
      digitalWrite(greenpin, green);
      digitalWrite(bluepin,  blue);
      relesepresure = 1;
  }
}

So in this code above, what I want to do is to store all the times the functions write either red, green, blue, yellow, etc. and display it on a computer screen in real time bar graphs. Something like Flot Examples but with bars.

So naturally I need to do somehing like this:

else if (color == 3) {

      //Color3++;
      //Update the bar graph with the new values (Color1,0),(Color2,1), (Color3,2), (Color4,3) where the numbers inside the paragraph are the x,y values of the graph.

      red   = 0;
      green = 0;
      blue  = 1;
      color = color + 1;
}

How can this be achieved since Arduino is a very limited language? I was thinking about writing these variable values to a simple .json file and read them from there with jQuery, but I don't know how to do that either. Is there a smarter solution?

I'm using an Arduino Mega .

Answer 1

First, you are going to have something going between JQuery and the Arduino Mega. Some of your options are:

• Access the arudino through a usb cable and use some sort of server based technology to access it, such as php. There is an example of how to do this here:

http://wanderr.com/jay/controlling-arduino-via-serial-usb-php/2010/12/28/

• Use an ethernet or wifi shield and provide the data back in the format of your choice. This would add about $30-60 to your cost but make the arduino part of this project self contained and not require a computer for it to run.

• if you want it wireless you could look into bluetooth and zigbee recievers. you would still need a server and something like php with this option.

• for flash, you typically use something called a serial socket server. There is more inforamation about this on the Aruduino Playground . It is possible you could also access the same type of server through jquery directly. This would be similar to the first option and would require a direct usb connection to the computer.

If you wanted to try something different, I would recommend looking at processing and firmata as there are lots of examples of how take data from an arduino and create some sort of visual based on that data.