ARDUINO FAN

This one controls the speed of a fan depending on the current temperature. The current temperature is looked up from Yahoo (you can enter your zip code). Python then maps that to a fan speed (temperature <=50 degrees: no fan; temperature >= 90 degrees: maximum speed).

COMPONENTS USED
- Arduino, breadboard
- DC motor
- Battery pack
- Resistors and transistors

PYTHON CODE
weather.py:
import xml.dom.minidom
import urllib2

def get_temperature(zipcode):
c=urllib2.urlopen("http://weather.yahooapis.com/forecastrss?p=" + str(zipcode) + "&u=f")
content=c.read()
doc = xml.dom.minidom.parseString(content)
el = doc.getElementsByTagName("yweather:condition")[0]
att = el.getAttribute("temp")
return int(att)

fan.py:
import sys
import time
import serial
import weather

ser = serial.Serial('/dev/tty.usbserial-A4001nKF', 9600)
def arduino_write(msg, ser):
ser.write(msg)
time.sleep(0.1)
def set_location(zipcode):
temperature = weather.get_temperature(zipcode)
# print temperature
def get_speed(temperature):
# print "temp: " + str(temperature)
minTemp = 50
maxTemp = 90
minSpeed = 1
maxSpeed = 255
speed = (temperature - minTemp) * maxSpeed / (maxTemp - minTemp)
speed = max(minSpeed, speed)
speed = min(maxSpeed, speed)
return speed
def set_speed(zipcode):
print "Setting fan speed according to temperature in " + str(zipcode)
temperature = weather.get_temperature(zipcode)
speed = get_speed(temperature)
print "Temperature: " + str(temperature) + ", fan speed: " + str(speed)
ser.write(str(speed))
def off():
ser.write(str(1))

ARDUINO CODE
int potPin = 0; // select the input pin for the potentiometer

int motorPin = 9; // select the pin for the Motor
int speed = 0;
int val = 0; // variable to store the value coming from the sensor
char serInString[100];

void setup() {

Serial.begin(9600);

}

void loop() {
//read the serial port and create a string out of what you rea
readSerialString(serInString);
speed = atoi(serInString);
// val = analogRead(potPin); // read the value from the sensor, between 0 - 1024

Serial.println(speed);

if(speed > 0) {
analogWrite(motorPin, speed); // analogWrite can be between 0-255
}
delay(50);
clearSerialString();
}

//read a string from the serial and store it in an array
//you must supply the array variable
void readSerialString (char *strArray) {
// clearSerialString();
int i = 0;
if(!Serial.available()) {
return;
}
while (Serial.available()) {
strArray[i] = Serial.read();
i++;
}
}

void clearSerialString() {
for (int i=0; i < 10; i++) {
serInString[i] = ' ';
}
}