usb data acquisition circuit for digital chart recorder

[Jonathan Cline]

now built for use with the UV-1 or similar signal monitor

source code below, very simple

i'll make this into some cleaned up post later.  including schematic and bill of materials.

// UBW Microcontroller Analog Data Acquisition ; 

// Source code for processing.org application

//

// jcl...@ieee.org 2009-03 Initial version

// jcl...@ieee.org 2013-06-10 Enhancements for use with UV Monitor from Amersham Biosciences

// jcl...@ieee.org 2013-06-13 Add averaging line with data points

import processing.serial.*;

Serial ubw; // USB microcontroller communication

int loops = 0;

int[] xvals;

void setup() {

  String ubwVersion;

  boolean found;

  float tdelay;

  found = false;

  size(1000,500);

  background(0); // black

  frameRate(10); // sets draw rate

  stroke(255); // white

  xvals = new int[width];

  try {

    println(Serial.list());

    ubw = new Serial(this, Serial.list()[2], 9600); // serial rate doesnt matter

    tdelay=millis() + 5000;

    // Read firmware version from connected UBW Microcontroller; jcline 2009-03

    for (int i=0; millis() < tdelay ; i++) {

        // Get+Verify UBW version string, print to console

        ubw.write("v\n");

        delay(100);

        ubwVersion = ubw.readStringUntil('\n');

        if (ubwVersion != null) {

          if (ubwVersion.startsWith("UBW", 0)) {

            println("Found UBW attached to USB:\n");

            println(ubwVersion);

            found = true;

            break;

          }

        }

    }

  }

  catch (Exception e) {

    println("device access error\n");

  }

  if (found != true) {

    println("No UBW found, exit\n");

    exit();

  }

  else {

    ubw.write("C,255,255,255,1\n");

    ubw.write("CU,1,0\n");

    ubw.write("T,200,1\n"); // set timered update in millisec, A=1

    ubw.clear(); // flush

  }

}

// Microchip's firmware uses %4u output for output of analog data values

// Convert "0023" string to Int 23

Integer string4uToInt(String s) {

   char a[] = s.toCharArray();

   Integer i = 0;

   Integer v;

   // char array into positional math based on ASCII value

   v = byte(a[0]) - 48;

   i += v * 1000;

   v = byte(a[1]) - 48;

   i += v * 100;

   v = byte(a[2]) - 48;

   i += v * 10;

   v = byte(a[3]) - 48;

   i += v;

   return (i);

}

// Read analog data depending on framerate & draw graphical level indicator

void draw() {

  String cmd;

  String data;

  Integer val;

  loops++;

  if (loops > 20000) {

    noLoop();

    ubw.write("T,0,1\n"); // Turn off timered updates

    println("done\n");

    ubw.stop();

  }

  data = ubw.readStringUntil('\n'); // read timered update

  if (data == null) {

    return; // no periodic data yet

  }

  if (data.startsWith("A,", 0) == false) {

    println("bad input: "+data+"\n");

    return;

  }

  

  val = string4uToInt(data.substring(2, data.length()));

  println(val);

  val = val/5;

  

  for(int i=1; i<width; i++) {

    xvals[i-1] = xvals[i];

  }

  

  stroke(255, 0, 0);

  xvals[width-1] = height - val;

  

  background(248, 248, 248);

  for(int i=4, sum = 0, sumLast = 0; i<width; i++) {

    //point(i, xvals[i]); // See processing.org's example "mouse signals"

    //point(i, xvals[i]-1);

    sum = xvals[i];

    sum += xvals[i-1];

    sum += xvals[i-2];

    sum += xvals[i-3];

    sum += xvals[i-4];

    sum /= 5;

    

    //line(i, xvals[i], i, xvals[(i-1)]);

    point(i, xvals[i]);

    line(i, sum, i, sumLast);

    line(i, sum+1, i, sumLast+1);

    sumLast = sum;

  }

}

--
## Jonathan Cline
## jcl...@ieee.org
## Mobile: +1-805-617-0223
########################