It’s a beagleboard clone with the exception that this version comes packed with a RJ45 10/100Mb ethernet connection, bluetooth and  802.11b/g wifi. Oh and the price is about the same as a beagleboard (it’s actually cheaper then a BB when you opt for the non-wifi version).

Here are some specs from the ISEE website:

• TI OMAP35x pin compatible family multicore processor
• ARM CORTEX A8 core
• DSP TMS320C64x+ core
• POWERVR SGX 530 core (OpenGL® ES 2.0, OpenGL® ES 1.0 , OpenVG)
• IVA2.2 (Video Hardware Accelerators)
• DDR RAM plus NAND Flash Package on Package (PoP) memories (on OMAP chip)
• Linux BSP available (Board Support Package)
• Ethernet 10/100 Mb BaseT.
• Wifi IEEE 802.11b/g + Bluetooth 2.0 (Integrated antenna).
• Compatibility with a huge collection of USB peripherals including hubs, keyboards, mice, web cameras, and much more.
• MicroSD connector.
• DVI-D for connecting digital computer monitors.
• Stereo audio in and out for a microphone and headphones or speakers.
• Expansion connector with I/O, SPI, UART…
• Expansion connector with access LCD lines.
• Wall plug 5 Vdc or JST input.
• RS-485 Transceiver.
• 2 ADC : 1 and 3 MSP/s.
• Temperature Range: -40 to +80º C.
• EMI and EMC precertificate. CE compliant.

Did I mention it’s really small? As in ‘Djeez that sure is really small!’.

I’ve mounted the IGEPv2 board on a lego structure to make (dis)connecting cables a bit easier and to prevent static discharges of causing any mayhem. The mounting holes in the pcb are spaced equal to the offset in the lego beams so there was no need for drilling or hotglue.

Of course this is just fine for use on your desktop but rather useless when trying to protect your precious board from the (or atleast some) elements. So I wanted an affordable case. ISEE sells a housing for 15EUR, but as I forgot to order one when ordering the board, the price of shipping about doubles that figure, crossing it from the list of options. Specialcomp has a housing for $29 making it even less of an option.

Borglabs has a cool tutorial on how to hack a $5 soap box to make an enclosure. This is definitely the best value for money you’ll get.

I liked the specialcomp acrylic housing but disliked the pricetag. So I deciced to make my own. I fired up sketchup and looked for a model of the IGEP board in the store, none were found. So as any sensible human being would do, instead of just using a box with some holes as a mockup, I had to draw the thing myself.

Some renders of the 3D-model:

Most of the parts were just downloaded from the store and I don’t take any credit for them. I just wanted a 3D model where connector positions were accurate enough to design a case.

The model is on a 1/1 scale and the .kmz file can be downloaded here : igepv2_revB_board

I’m getting some errors uploading the model to the sketchup store but I’ll post a link when it’s done.

Only thing left to do now is design a case. And when I have a few spare moments, I will.

So watch out for a future post with a 3D model of a case and probably some instructions on how to reproduce and assemble one yourself.

Notes :

• for this setup the connections are made on the ethernet shield instead of directly on the arduino. Since Fritzing misses a library with external shield I used the arduino, the pinout stays the same either way.
• check the DS18B20 datasheet for the specifications on hooking up the sensor in parasite or powered mode

Schematics :

The arduino reads the sensors every 10 seconds and passes the data to a php script on your website; which then stores the data in a text file. A second script generates a line chart of the collected data.

22 hours of temperature data

I started from Cyberspice’s code and changed the arduino code to make use of the DB18S20 and the ethernet shield.

A variable was added to the upload php script in order to store the light intensity in addition to the temperature.

The graphing script was altered to also display the minimum temperature, the maximum temperature, the current temperature and the average temperature. A raster was added for a better interpretation of the plotted data and a green line is showing the average temperature  troughout the chart.

You need to alter your ip, domain and path as I explained in the post Arduino Wireless motion detector so I won’t go into those details here.

The arduino sketch :

#include <OneWire.h>
#include <string.h>
#include <Ethernet.h>

int count = 0;
OneWire ds(8);
int HighByte, LowByte, TReading, SignBit, Tc_100, Tf_100, Whole, Fract;
int Tcount = 1;
int W[6];
int F[6];
int photocellPin = 0;     // the cell and 10K pulldown are connected to a0
int light;     // the analog reading from the sensor divider

byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = {
  192, 168, 1, 36};
byte server[] = { 77, 222, 78, 32};
// String buffer
char buffer[256];

Client client(server, 80);

void setup()
{
  Ethernet.begin(mac, ip);
  Serial.begin(9600);

  delay(1000);

  // Serial.println("connecting...");

}

void loop()
{
  byte i;
  byte present = 0;
  byte data[12];
  byte addr[8];

  if ( !ds.search(addr)) {
    ds.reset_search();
    return;
  }

  ds.reset();
  ds.select(addr);
  ds.write(0x44,1);         // start conversion, with parasite power on at the end

  delay(1000);            

  present = ds.reset();
  ds.select(addr);
  ds.write(0xBE);         // Read Scratchpad

  light = analogRead(photocellPin);
  Serial.print("light intensity = ");
  Serial.print(light);
  Serial.print("\n");
  for ( i = 0; i < 9; i++) {           // we need 9 bytes
    data[i] = ds.read();
  }

  LowByte = data[0];
  HighByte = data[1];
  TReading = (HighByte << 8) + LowByte;
  SignBit = TReading & 0x8000;  // test most sig bit
  if (SignBit) // negative
  {
    TReading = (TReading ^ 0xffff) + 1; // 2's comp
  }
  Tc_100 = (6 * TReading) + TReading / 4;    // multiply by (100 * 0.0625) or 6.25

  Whole = Tc_100 / 100;  // separate off the whole and fractional portions
  Fract = Tc_100 % 100;

  if (SignBit) // If its negative
  {
    Serial.print("-");
  }
  Serial.print(Whole);
  Serial.print(".");
  if (Fract < 10)
  {
    Serial.print("0");
  }
  Serial.print(Fract);
  Serial.print(" C\n");

  if (client.connect()) {
    Serial.println("connected");
 sprintf(buffer, "HEAD /path/to/script/newtemp.php?count=%d&temp=%d.%d&light=%d HTTP/1.1", Tcount, Whole, Fract, photocell);
 client.println(buffer);
 client.println("Host: yourdomain.com");
 client.println("Connection: close");
 client.println();
 client.stop();
 Tcount++;
 }
 else {
 Serial.println("connection failed");
 }
 delay(60000);  // wait 1 minute before sending new data
}

The upload script  ‘newtemp.php’ :

<?php

if ($_SERVER['REQUEST_METHOD'] == 'HEAD') {

	$fields = explode("&", $_SERVER['QUERY_STRING']);
	$values = array();

	foreach ($fields as $field) {
		$keyval = explode("=", $field);
		$values[$keyval[0]] = $keyval[1];
	}

	$file = fopen('./tempdata.txt','a+');
	if ($file) {
		fwrite($file, time() . ':' . $values['count'] . ':' . $values['temp'] . ':' . $values['light']);
		fwrite($file, "\n");
		fclose($file);
	}
}

?>

The graphing script ‘tempgraph.php’ :

<?php

define('WIDTH', 1000);
define('HEIGHT', 520);
define('FONT', 1);
 define('FONT2',2);

// Get the temperature data
$data = array();
$file = fopen("./tempdata.txt","r");
if ($file) {
	while (!feof($file)) {
		$line = trim(fgets($file));
		if (strlen($line)) {
			$fields = explode(":", $line);
			$keyval = array();
			$keyval['time']        = $fields[0];
			$keyval['count']       = $fields[1];
			$keyval['temperature'] = $fields[2];
			$keyval['light'] 	   = $fields[3];
			$data[] = $keyval;
		}
	}

	fclose($file);
}

// Get the number of data points
$datapoints = count($data);

// Lines are chronological
$mintime = $data[0]['time'];
$maxtime = $data[$datapoints - 1]['time'];

// Temperatures need to be processed.
$mintemp = $data[0]['temperature'];
$maxtemp = $data[0]['temperature'];

foreach ($data as $datapoint) {
	$mintemp = $mintemp < $datapoint['temperature'] ?
	           $mintemp : $datapoint['temperature'];
	$maxtemp = $maxtemp > $datapoint['temperature'] ?
	           $maxtemp : $datapoint['temperature'];
	$avgtemp += $datapoint['temperature'];
	$curtemp = $datapoint['temperature'];
}
 $avgtemp = round(($avgtemp / $datapoints),2);

// Get the axis dimensions.  Round up and down to the nearest
// degree C and hour.
$lowtime  = intval($mintime / 3600) * 3600;
$hightime = (intval($maxtime / 3600) + 1) * 3600;
$difftime = $hightime - $lowtime;

$lowtemp  = intval($mintemp);
$hightemp = intval($maxtemp) + 1;
$difftemp = $hightemp - $lowtemp;

// Create the image
$image = imagecreate(WIDTH, HEIGHT);
if ($image) {
	$background = imagecolorallocate($image, 255, 255, 255);
	$black      = imagecolorallocate($image, 0, 0, 0);
	$red        = imagecolorallocate($image, 255, 0, 0);
	$blue       = imagecolorallocate($image, 0, 0, 255);
	$green		= imagecolorallocate($image, 0, 204, 5);
	$grey		= imagecolorallocate($image, 210,210,210);

	// Draw the axes
	imageline($image, 20, 20, 20, 485, $black);
	imageline($image, 15, 480, 980, 480, $black);
	imageline($image, 15, 20, 20, 20, $black);
	imageline($image, 980, 480, 980, 485, $black);

	// Draw top horizontal line
	imageline($image, 20, 20, 980, 20, $grey);

	// Draw right most vertical line
	imageline($image, 980, 20, 980, 479, $grey);

	for ($i = 3600; $i < $difftime; $i += 3600) {
		$x = 20 + (($i * 960) / $difftime);
		// Draw ticks on horizontal axis
		imageline($image, $x, 480, $x, 483, $black);
		// Draw horizontal guides
		imageline($image, $x, 479, $x, 20, $grey);
	}
	$temp = intval($lowtemp);
	for ($i = 1; $i < $difftemp; $i++) {
	    $y = 480 - (($i * 460) / $difftemp);
		// Draw ticks on vertical axis
		imageline($image, 17, $y, 20, $y, $black);

		// Draw vertical guides
		imageline($image, 21, $y, 980, $y, $grey);
		$temp = intval($temp) + 1;
		$ytemp = intval($y) - 5;
		//if($temp % 2 == 0){
			imagestring($image, FONT, 0, $ytemp, $temp . 'C', $black);
		//}
	}

	// Draw the labels
	imagestring($image, FONT, 8, 490, date("H:i", $lowtime), $black);
	imagestring($image, FONT, 970, 490, date("H:i", $hightime), $black);
	imagestring($image, FONT, 0, 475, $lowtemp . 'C', $black);
	imagestring($image, FONT, 0, 15, $hightemp . 'C', $black);

	// Draw min, max and avg
	imagestring($image, FONT2, 700, 430, "Cur. temp : " . $curtemp . " °C",$black);
	imagestring($image, FONT2, 700, 450, "Avg. temp : " . $avgtemp . " °C",$green);
	imagestring($image, FONT2, 850, 430, "Min. temp : " . $mintemp . " °C",$blue);
	imagestring($image, FONT2, 850, 450, "Max. temp : " . $maxtemp . " °C",$red);

	// Draw avg line

	$avgtemp = 480 - ((($avgtemp - $lowtemp) * 460) / $difftemp);
	imageline($image,20, $avgtemp, 980, $avgtemp, $green);

	// Draw the temperature points

	// Position of the first point
	$prevx = (($data[0]['time'] - $lowtime) * 960) / $difftime;
	$prevy = (($data[0]['temperature'] - $lowtemp) * 460) / $difftemp;

	// Draw line from previous point to current point
	for ($i = 1; $i < $datapoints; $i++) {
		$x = (($data[$i]['time'] - $lowtime) * 960) / $difftime;
		$y = (($data[$i]['temperature'] - $lowtemp) * 460) / $difftemp;
		imageline($image, $prevx + 20, 480 - $prevy, $x + 20, 480 - $y, $red);
		$prevx = $x;
		$prevy = $y;
	}

	// Finally time and date stamp
	$generated = 'Generated: ' . date("r");
	imagestring($image,
	            FONT,
	            WIDTH - 15 - (imagefontwidth(FONT) * strlen($generated)),
	            HEIGHT - 15,
	            $generated,
	            $blue);

	// Output the image
	header('Content-Type: image/png');
	imagepng($image);

	// Destroy it
	imagedestroy($image);
}

?>

I will soon post some improvements on the scripts :

• averaging 6 readings ( 1 minute ) to 1 datapoint to get rid of the noise
• let the script fill one text file for each day, so you can look at a history over several days
• split up data into different charts
• last but not least, trying to add the S65 in the game : showing the current sensor readings or a graph

Please leave a comment or send me a link to show your arduino projects!

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