Resistance meter

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Revision as of 08:48, 23 May 2014 by Pkj (talk)
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Objective

The course will show you how to use Processing to display the graph of the ohmmeter value, and the ohmmeter will be achieved by microduino.

Equipment

  • Other Hardware Equipment
    • A USB cable
    • A 20k Ω resistor
    • A 104 ceramic capacitor
    • A bread board
    • A box of jumpers


Schematic Diagram

ResistanceMeterSchematics.jpg


Program

Referring to ResistanceMeter

processingResistanceMeter

Debugging

Step 1:Building hardware environment according to the schematic diagram, just as follows:

IResistanceMeterConnectionDiagram.jpg


Step 2:Here is the code we need:

The code of two ends (Processing and Microduino)

Microduino:

//Using filter algorithm to calculate resistance and displaying the data on Processing via serial output.

 //filter Algorithm
 float filter()
 {
   float sum = 0;
   for(int count = 0; count < N; count++)
   {
     sum += r;
     delay(5);
   }
   return (float)(sum / N);
 }

Processing:

//After getting the data of the first serial port, you can define or cache the data if there is a new line.

// is always my Microduino, so I open Serial.list()[0].
// Open whatever port is the one you're using.
myPort = new Serial(this, Serial.list()[0], 9600);
myPort.bufferUntil('\n'); // Trigger a SerialEvent on new line

//On the screeen, displaying the data received from Microduino in the form of graph and marking scale.

 String val = myPort.readStringUntil('\n');
 if (val != null) {
   if ("Infinity!!".equals(val)) {
     unit="resistancetoo big";
   } 
   else {
     if ("K ohm".equals(val)) {
       unit="K ohm";
     }
     else if (" ohm".equals(val)) {
       unit=" ohm";
     }
     else {
       val = trim(val);
       println(val);
       resistance=Float.parseFloat(val);
     }
   }
 }
 vals[vals.length-1] = 200-resistance;
 //Display scale
 text ( "200-", 370, 10); 
 text ( "--", 370, 50); 
 text ( "100-", 370, 100);
 text ( "--", 370, 150); 
 text ( "0-", 370, 200); 
 //show current num
 text ( resistance+unit, 0, 10);

Step 3:Uploading the code and compiling it successfully.

Step 4: Putting the resistor ready to measure between the yellow and the black lines on the graph, watching resistance on Processing.

Result

The graph will display the current resistance.

IResistanceMeterResult.jpg


Video