Temperature Sensor Stability Performance

Hi,

I have a Galileo Gen 2 and I have connected an LM35 based temperature sensor from DFRobot. 

I have connected it to A5 on an I/O Expansion shield also from DFRobot and I am using an external power supply to power the Galileo. I checked the power at pins with a dvm and get 4.95-4.96V and it is very steady.

I have a very simple sketch to read the values and send them to the serial monitor. I try this in 10 bit and 12 bit resolution. The values and the range seem quite large and the noise signal is not a normal distribution, more random. The values scale exactly as anticipated in going from 10 bit to 12 bit.

the temperature conversion is 0.010mV/C so these ranges are quite large (70-35=35). 35/1024*5V = 0.17V which translates to 17 degrees. The sensor was just sitting in air next to me.

Does any one have data to compare? When I look online most discussion refers to uncontrolled Vcc but I measured it and it seems stable.

Temperature Readings.png (209.21 KiB) Downloaded 1215 times 
// the setup routine runs once when you press reset:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
analogReadResolution(12);
}


// the loop routine runs over and over again forever:
void loop() {
// read the input on analog pin 5:
int sensorValue = analogRead(A5);
// print out the value you read:
Serial.println(sensorValue);
delay(200); // delay in between reads for stability
}