Tuesday, 5 November 2013

Plot a graph with Arduino Yun

This is a short article, some "tips&tricks" if you need to plot a chart with data generated from the Arduino Yun.
I report it here, just to report my work.

This article starts from this: http://arduino.cc/en/Tutorial/TemperatureWebPanel that explain how to use the Bridge to capture data from a temperature Sensor and make the data accessible from a web page inside an sdcard on the Yun.

Plot a chart
My scripts, it helps to plot the last 5 temperatures.
You have to change a little bit the script on the page and replace some files.

1 - I've added this at the beginning of the arduino script:
float lastTemp[5];
to save the last 5 temperatures
2 - Replaced  this part
      client.print("Current time on the Yun: ");
      client.println(timeString);
      client.print("
Current temperature: ");
      client.print(temperature);
      client.print(" degrees C");
      client.print("
This sketch has been running since ");
      client.print(startString);
      client.print("
Hits so far: ");
      client.print(hits);
with this one:
      lastTemp[hits%5] = temperature;
      for(int i=0;i<5 br="" i="">        client.print(lastTemp);
        client.print(";");
      }
      client.println(timeString+";"+startString+";"+hits+";");


So the page from arduino now it retuns all the data plus the last 5 temperature read, separated by ";"

3 - I've replaced the files in /arduino/www/TemperatureWebPanel with the ones HERE: it uses jquery and jflot

This is the final plot:


This is not the rightway
My script plot the last 5 request read from the sensor, but the right way is to leave the arduino part to ciclic fetch the temperature and save it on a file on the sdcard.
The html/js page need to read the same file and plot the temperatures with the data from the file.
I will update it later with a new solution.

2 comments:

  1. This comment has been removed by the author.

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  2. Schau Dir doch mal den Code an.
    Da stimmt doch was nicht.

    Es muss wohl eher so aussehen.

    lastTemp[hits % 5] = temperature;
    for(int i=0;i<5; i++)
    {
    client.print(lastTemp[i]);
    client.print(";");
    }
    client.println(timeString+";"+startString+";"+hits+";");

    ReplyDelete