Whitespace is driven partly by a bunch of people who started/helped growing, hackerspace Brussels but live in Ghent and wanted to skip the commute. The other part are  new enthousiastic locals (like me) who are commited to build something great.

Check out the Whitespace website at 0×20.be . If you don’t know what a hackerspace is have a look at http://hackerspaces.org/wiki/

Whitespace has it’s official opening at the beginning of spring in the weekend from the 19th to the 21st of March.

Feel free to drop by for a drink, a snack and some resistors! Hope to see you then!

Here’s a flyer for the event:

Make sure to check the website for a more complete and up to date agenda.

Whitespace is located at Blekerijstraat 75, 9000 Gent in Belgium.

Ripped shameless from BoingBoing

Check his myspace and homepage for more great stuff.

Page views have been doubling week by week and I’m receiving nice feedback and comments from visitors all over the globe.

A simple projection shows what this graph will look like 11 months from now…

On a serious note, new posts will probably be non-excistent for the next 2 months as I have exams comming up in january.

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This tutorial couldn’t be much easier, as a matter of fact you should be ashamed of yourself for even reading this! I’m just kidding, follow the next couple of steps and you’ll be wrestling the mighty python in a matter of minutes.

In the top toolbar go to  ‘Applications > Ubuntu Software Center’

Search for IDLE in the Ubuntu Software Center

Select the package ‘IDLE (using Python-2.6)’, hit the arrow and select ‘Install’ on the next page

After a few seconds, depending on your internet connection and processing power, the installation of IDLE is completed.

To start IDLE go to ‘ Applications > Programming > IDLE (using Python-2.6)’

Now you’re setup and ready to write  your first function…

If you’re new to Python and have little to no programming experience I recommend starting from one of two (or both) places.

Dive into Python and Think Python : How to Think Like a Computer Scientist provide excellent sources for unleashing your inner codeninja. ( Oh and the books are available for free in HTML, PDF and a bunch of other formats).

Go and discover your skills grashopper!

I’ll soon post a guide on setting up Eclipse on Ubuntu 9.10 and configuring the PyDev plugin to use Eclipse as your Python IDE.

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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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Since today was a holiday (here in Belgium) I had a few moments to spare so I wrote a quick and dirty version of pong for the arduino using the S65 shield.

Check the video after the break…

EDIT: Added sound using a buzzer

EDIT: Didn’t get time to rewrite some things, just added some comments

#include <S65Display.h>
#include <RotaryEncoder.h>
#include <string.h>

#define WIDTH 176
#define HEIGHT 132
#define BAT_WIDTH 5
#define BAT_HEIGHT 30
#define BAT_INIT_X 5
#define BAT_INIT_Y 56
#define BALL 5
#define BAT_STEP 5
#define AI_STEP 2
#define MAX_TURNS 5

float ball_x = WIDTH / 2;
float ball_x_prev = ball_x;
float ball_y = HEIGHT / 2;
float ball_y_prev = ball_y;
float ball_dir = 0;
float bat_1_dir = 0;
int bat1_x = BAT_INIT_X;
int bat1_y = BAT_INIT_Y;
int bat1_y_prev = bat1_y;
int bat2_x = WIDTH - BAT_INIT_X - BAT_WIDTH;
int bat2_y = BAT_INIT_Y;
int bat2_y_prev = bat2_y;
int bat2_step = AI_STEP;
int p1_score = 0;
int p2_score = 0;
int ball_angle = 0;          // angle between ball path and horizontal axis
int ball_angle_sign = 0;   // sign of ball_angle : up = +1, down = -1, horizontal = 0
boolean score = false;
boolean gameover = false;
char buffer[256];           // string buffer

S65Display lcd;
RotaryEncoder encoder;

// Encoder must be serviced regularly.
ISR(TIMER2_OVF_vect)
{
  TCNT2 -= 250;        //1000 Hz
  encoder.service();
}

void setup()
{
  lcd.init(2);
  encoder.init();
  // More encoder stuff
  //init Timer2
  TCCR2B  = (1&lt;&lt;CS22);           //clk=F_CPU/64
  TCNT2   = 0x00;
  TIMSK2 |= (1&lt;&lt;TOIE2);         //enable overflow interupt
  score = false;
  gameover = false;
  lcd.clear(0);
  initTurn();
  startGame();
}

void loop(){

  while(!score &amp;&amp; !gameover){
    checkControls();
    updateAI();
    updateFields();
    drawScreen();
    delay(10);
  }

  if(checkPress() &amp;&amp; !gameover){	// if a player scored wait for rotary press
    initTurn();
  }
  delay(10);
}

// initialize fields for the beginning of game/round
void initTurn(void){
  lcd.clear(0);
  ball_x = WIDTH / 2;
  ball_x_prev = ball_x;
  ball_y = HEIGHT / 2;
  ball_y_prev = ball_y;
  ball_dir = 0;
  bat1_x = BAT_INIT_X;
  bat1_y = BAT_INIT_Y;
  bat1_y_prev = bat1_y;
  bat2_x = WIDTH - BAT_INIT_X - BAT_WIDTH;
  bat2_y = BAT_INIT_Y;
  bat2_y_prev = bat2_y;
  ball_angle = 0;           // angle between ball path and horizontal axis
  ball_angle_sign = 0;    // up = +1, down = -1, horizontal = 0
  score = false;
  ball_dir = 1;
  ball_angle = 45;
}

// start the game and wait for press on rotary encoder
void startGame(void){
  lcd.drawText(35, 60, "Click to start", RGB(255,255,255), RGB(0,0,0));
  while(!checkPress()){
    delay(10);
  };
  lcd.clear(0);
}

// checks if rotary encoder was pressed
boolean checkPress(void){
  int8_t press;
  press = encoder.sw();
  if (SW_PRESSED == press || SW_PRESSEDLONG == press) {
    return true;
  }
  else{
    return false;
  }
}

void checkRotation(void){
  moveBat(encoder.step());
}

void checkControls(void){
  if(checkPress()){    // pause
    lcd.drawText(45, 60, "Game paused", RGB(255,255,255), RGB(0,0,0));
    while(!checkPress()){ // wait until pressed
    }
    lcd.clear(0);
  }
  checkRotation();
}

void moveBat(int rot){
  if(!score &amp;&amp; !gameover){
    if(rot == 1){                                  // clockwise rotation, move bat up
	if(bat1_y - BAT_STEP &gt;= 0){   // only move up when there is enough space left
	  bat1_y -= BAT_STEP;
	}
    }
    else if(rot == -1){                         // anti-clockwise rotation, move bat down
        // only move down when there is enough space left
	if((bat1_y + BAT_HEIGHT + BAT_STEP) &lt; HEIGHT){
	  bat1_y += BAT_STEP;
	}
    }
  }
}

void updateFields(void){
 // top or bottom of screen reached, bounce ball back
  if(ball_y &lt;= 0 || ball_y + BALL &gt;= HEIGHT){
    if(ball_angle_sign == -1){ // ball was going down
	ball_angle_sign = 1;    // ball is now going up
    }
    else{                            // ball was going up
	ball_angle_sign = -1;   // ball is now going down
    }
  }
  // check if ball has is in reach of bat1 (horizontal), for some reason checking for equality doens't seem to work here ?
  if((ball_x &lt;= 12 &amp;&amp; ball_x &gt;= 11) &amp;&amp; (ball_dir == 1)){
    // ball is in reach of bat1(vertical)
    if((ball_y + BALL) &gt;= bat1_y &amp;&amp; ball_y &lt;= (bat1_y + BAT_HEIGHT)){
	ball_dir = 0;     // ball hits bat1, change direction
    }
  }
   // check if ball has is in reach of bat2 (horizontal)
  if((ball_x &gt;= 160 &amp;&amp; ball_x &lt;= 162) &amp;&amp; (ball_dir == 0)){
     // ball is in reach of bat2 (vertical)
    if((ball_y + BALL) &gt;= bat2_y &amp;&amp; ball_y &lt;= (bat2_y + BAT_HEIGHT)){
	ball_dir = 1;	      // ball hits bat2, change direction
    }
  }

  if( ball_x &gt; 0 &amp;&amp; ball_x + BALL &lt; WIDTH){           // ball is not near left or right edge
    if(ball_dir == 0){								// ball is moving to the right
	ball_x += cos(ball_angle);						// cosine is always positive in 1st and 4th quadrant
	if(ball_angle_sign == -1){						// check sign of angle
	  ball_y  -= sin(ball_angle);						// negative if angle in 4th quadrant
	}
	else{
	  ball_y  += sin(ball_angle);						// positive if angle in 1th quadrant
	}
    }
    else{									        // ball is moving to the left
	ball_x -= cos(ball_angle);						// cosine is always negative in 2nd and 3rd quadrant
	if(ball_angle_sign == -1){
	  ball_y  -= sin(ball_angle);						// sine is always negative in 3rd quadrant
	}
	else{
	  ball_y  += sin(ball_angle);						// sine is always positive in 2nd quadrant
	}
    }

  }
  else{										// ball hits left or right edge
    if(!score &amp;&amp; !gameover){
	if(ball_dir == 0){							        // ball was going to the right
	  if(p1_score++ &lt; MAX_TURNS){
	    p1_score++;								// player 1 scores
	  }
	  else{
	    gameover = true;
	  }
	}
	else{									        // ball was going to the left
	  if(p2_score &lt; MAX_TURNS){
	    p2_score++;								// player 2 scores
	  }
	  else{
	    gameover = true;
	  }
	}
	score = true;
    }
  }
}

void updateAI(void){
  // bat2 follows vertical position of ball, TODO : implement difficulty levels
  if(ball_y &gt; (bat2_y + (BAT_HEIGHT / 2))){
    // TODO : make function moveBat() that does the bound checking
    if((bat2_y + BAT_HEIGHT + bat2_step) &lt; HEIGHT){
	bat2_y += bat2_step;
    }

  }
  else{
    if((bat2_y - bat2_step) &gt;= 0){
	bat2_y -= bat2_step;
    }
  }
}

void drawScreen(void){
  // draw ball
  lcd.drawRect( ball_x_prev, ball_y_prev, ball_x_prev + BALL, ball_y_prev + BALL, RGB(0,0,0));
  lcd.drawRect( ball_x, ball_y, ball_x + BALL, ball_y + BALL, RGB(255,255,255));
  ball_x_prev = ball_x;
  ball_y_prev = ball_y;
  // draw left bat
  lcd.drawRect( bat1_x, bat1_y_prev, bat1_x + BAT_WIDTH, bat1_y_prev + BAT_HEIGHT, RGB(0,0,0));
  lcd.drawRect( bat1_x, bat1_y, bat1_x + BAT_WIDTH, bat1_y + BAT_HEIGHT, RGB(255,255,255));
  bat1_y_prev = bat1_y;
  // draw right bat
  lcd.drawRect( bat2_x, bat2_y_prev, bat2_x + BAT_WIDTH, bat2_y_prev + BAT_HEIGHT, RGB(0,0,0));
  lcd.drawRect( bat2_x, bat2_y, bat2_x + BAT_WIDTH, bat2_y + BAT_HEIGHT, RGB(255,255,255));
  bat2_y_prev = bat2_y;
  drawScore();
}

void drawScore(void){
  sprintf(buffer, "%d - %d", p1_score, p2_score);
  lcd.drawText(72, 5, buffer, RGB(255,255,255), RGB(0,0,0));
}

Be sure to check out the other videos …

MAKE presents : the LED

MAKE presents : the Resistor

MAKE presents : the Capacitator

MAKE presents : the Transistor

MAKE presents : the Diode

MAKE presents : the Integrated Circuit (IC)

Each time motion is detected, the networked arduino connects to the web and executes a php script which writes the time and date of the event to a text file. When you want to check if motion was detected, acces a different php script which displays all (if any) recorded events.

Check my next post to see how to send sensor data from the arduino to a website using php.

If you followed part 1 and part 2 all you need to do for part 3 is change the code of the receiving arduino since we’re only changing the output from ‘blink a led’ to ‘access a website’.

Sketch :

#include <Ethernet.h>

int ledPin = 13;    // pin for the LED
int RFinPin = 8;    // pin for the RF receiver
int val = 0;         // variable for reading the pin status
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };    // unique mac address
byte ip[] = { 192, 168, 1, 36};        // unique and valid ip for your network
byte server[] = { 77, 222, 78, 32};  // ip google

void setup() {
   Ethernet.begin(mac, ip);
   pinMode(ledPin, OUTPUT);    // declare LED as output
   pinMode(RFinPin, INPUT);    // declare RF receiver as input
   Serial.begin(9600);
   delay(1000);
}

Client client(server, 80);

void loop(){
   val = digitalRead(RFinPin);        // read input value
   if (val == HIGH) {
     digitalWrite(ledPin, HIGH);      // turn LED ON
     if (client.connect()) {
       Serial.println("connected");
       client.println( "GET /folder/movement.php HTTP/1.1");
       client.println("Host: yourdomain.com");
       client.println("Connection: close");
       client.println();
       client.stop();
     } else {
       Serial.println("connection failed");
     }
   } else {
     digitalWrite(ledPin, LOW);       // turn LED OFF
   }
   delay(5000);
}

The script movement.php is executed when the arduino connects to www.yourdomain.com/folder/movement.php

movement.php code :

<?php

$myFile = "movement_data.txt";
$fh = fopen($myFile, 'a') or die("can't open file");
$stringData = date("D, d M Y H:i:s") . "\n";
fwrite($fh, $stringData);

fclose($fh);

?>

The script display_movement.php takes the movement data and prints one line for every event recorded.

display_movement.php code:

<?php

 $fileName = "movement_data.txt";

 if(file_exists($fileName)){
      $file = fopen($fileName,'r');

      while(!feof($file)){
                $name = fgets($file);
                if($name != NULL){
                echo('<br>'. "Movement registered on : ".$name.'</br>');
			}
        }

        fclose($file);
}
?>

When display_movement.php is executed you should see something like :

In the next post I’ll discuss how to write sensor data (light intensity, temperature,…) to a website and plot a line chart using php.

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Rossum made a an awesome device with just an 8-bit Atmel AVR ATmega644 processor and a cheap touchscreen LCD.