Making Things Talk

APPENDIX C 381

else {

// if the sensor value is less than the threshold,

// and the previous value was greater, then the cat

// just left the mat

if (prevSensorValue >= threshold) {

catOnMat = false;

}

}

// save the sensor value as the previous value

// so you can take new readings:

prevSensorValue = sensorValue;

if (requestInProgress == true) {

checkNetClient();

}

}

// serialEvent method is run automatically by the Processing applet

// whenever the buffer reaches the byte value set in the bufferUntil()

// method in the setup():

void serialEvent(Serial myPort) {

// read the serial buffer:

String myString = myPort.readStringUntil(linefeed);

// if you got any bytes other than the linefeed:

if (myString != null) {

//trim off the carriage return and convert the string to an integer:

sensorValue = int(trim(myString)) /2 -100;

// print it:

// println(sensorValue);

drawGraph();

}

}

void drawGraph() {

int lineHeight = sensorValue /2;

// draw the line:

if (catOnMat) {

// draw green:

stroke(0,255,0);

}

else {

// draw red:

stroke(255,0,0);

}

line(graphPosition, height, graphPosition, height - lineHeight);

// at the edge of the screen, go back to the beginning:

if (graphPosition >= width) {

graphPosition = 0;

background(0);

}

else {

graphPosition++;

}

}

void sendMail() {

// calculate the current tim