Using multiple DS18B20 sensors with SD logger sheild

[seneca]

I'm brand new to Arduino, but I would like to use two DS18B20 sensors with the SD logger shield. How would I hook them up to the shield? I klnow they are digital instead of the analog ones that come with the shield. How would the code change?

[adafruit_support_rick]

You can connect the sensors to the shield using the prototyping area. Both sensors share the same data pin. You need a single 4.7k resistor as a pullup, connected between the data pin and 5V.


There is a Dallas Temperature Control Library for arduino available here:
http://www.milesburton.com/?title=Dalla ... ol_Library

That library requires the general=purpose arduino One Wire library, available here:
http://www.pjrc.com/teensy/td_libs_OneWire.html

[seneca]

So how would the code in the sketch need to be modified now that I am using a digital sensor instead of the analog sensor?

[adafruit_support_rick]

Well, if you're looking at the sample code from the tutorial, this section of code determines the temperature in degrees C:

Code: Select all

  tempReading = analogRead(tempPin);  
  
  Serial.print("Temp reading = ");
  Serial.print(tempReading);     // the raw analog reading
  
  // converting that reading to voltage, which is based off the reference voltage
  float voltage = tempReading * aref_voltage / 1024; 
 
  // print out the voltage
  Serial.print(" - ");
  Serial.print(voltage); Serial.println(" volts");
 
  // now print out the temperature
  float temperatureC = (voltage - 0.5) * 100 ;  //converting from 10 mv per degree wit 500 mV offset
                                               //to degrees ((volatge - 500mV) times 100)
  Serial.print(temperatureC); Serial.println(" degrees C");

With the Dallas Temperature Control Library, you would replace that section of code with this:

Code: Select all

  float temperatureC = sensors.getTempCByIndex(0)); //  0 refers to the first DS18B20 on the wire
  Serial.print(temperatureC); Serial.println(" degrees C");

The example code shows how to set up the library and create the "sensors" object