calculating with analog input values

hello,

i've tried create thermometer using arduino temperature sensor.

however, reason can arduino send me value read analog port, using analogread() store in value, , using serial.println() print in serial monitor.

however moment start trying calculate value, sends 0.

here's code used;

code: [select]

// thermometer: gets voltage sensor connected analog pin 5, calculates temperature this, , sends serial port every second

#define sensor 5

int val = 0;
float voltage = 0;
int temperature = 0;

void setup()
{
 serial.begin(9600);    //open serial port
}

void loop ()
{
 val = analogread(sensor);
 serial.println(val);
 voltage = ((val/1023)*5);
 serial.println(voltage);
 temperature = ((voltage - 0.5) * 100);
 serial.println(temperature);
 delay(1000);
}

the arduino returns; 142 (that's analog read value)
0.00 (obviously did wrong calculation)
-50 ((0 - 0.5) *100 -50 of course)

please help!

i suspect calculations running problems because of use of float , int variables in same statements. i'll let stronger software people explain better can, it's common mistake beginners make.

lefty

Arduino Forum > Forum 2005-2010 (read only) > Software > Syntax & Programs > calculating with analog input values

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