Evil Spider 2

This is a new version of the evil spider. I've replaced the LED in the head with two smaller LEDs in the eyes. This way the brightening is easier to see.

Some close-up photos are at the end of this post - if you fear spiders, scroll slowly down to the image with breadboard ;-)

The source code is rather simple:

/*  Spider - sketch for spider control
 *
 *  12. Apr 2012   danimath   created
 *  02. May 2012   danimath   added blinking
 *
 **********************************************************************/
byte          usPin = 8;       // ultrasound pin
unsigned long usDuration;      // ultrasound duration
unsigned int  cm;              // roughly calculated cm
byte          ledPin = 3;      // LED pin
int           brightness;      // LED brightness
int           min_threshold =  15 ; // treshold for blinking LED
const int     max_threshold = 100; // treshold for brightning LED
const int     mesDelay = 250;  // msec between measurements

//#define DEBUG

/*   setup - initialise things
 *
 **********************************************************************/
void setup ()
{
#ifdef DEBUG
    Serial.begin (9600);
#endif
    analogWrite (ledPin, 255);
    usDuration = getDist ();  // warm up measurement
    delay (2500);
    analogWrite (ledPin, 0);
}

/*   loop - the ever lasting loop
 *
 **********************************************************************/

void loop ()
{
    usDuration = getDist ();
    cm = usDuration / 58;  // int is enough for this
#ifdef DEBUG
    Serial.print   ("usDuration: ");
    Serial.println (usDuration);
#endif
    if (cm < min_threshold)
    {
        if (brightness == 0)
            brightness = 255;
        else
            brightness = 00;
    }
    else if (cm < max_threshold)
        brightness = map (cm, 0, max_threshold, 200, 0);
    else
        brightness = 0;
    analogWrite (ledPin, brightness);
    delay (mesDelay);
}

/*   getDist - gets the distance from SRF05
 *
 *   return value: micro seconds
 *
 **********************************************************************/
unsigned long getDist ()
{
    unsigned long retVal;

    pinMode (usPin, OUTPUT);
    digitalWrite (usPin, LOW);
    delayMicroseconds (2);
    digitalWrite (usPin, HIGH);
    delayMicroseconds (10);
    digitalWrite (usPin, HIGH);

    pinMode (usPin, INPUT);
    retVal = pulseIn (usPin, HIGH);
#ifdef DEBUG
    Serial.print   (retVal);
    Serial.print   (", ");
    Serial.print   (retVal / 58.0);
    Serial.println (" cm");
#endif
    return (retVal);
}

The hardware is just as simple as the software. This image is created with Fritzing. Of course I didn't use a breadboard in the final construction.

As promised here are the close-ups: