Improve DS18B20 resolution

[Totche]

Hello everybody.

I would like to know if it was possible to improve the resolution for the DS18B20 sensors.

The goal is to have a reading of XX.XX degrees instead of XX.X.

In the DallasTemperature.CPP, i have seen "DallasTemperature::setResolution", but i don't know how to use it in the sketch, certainly in the setup(), i think.

Thanks for answers

[ericvdb]

You can do as follows:

//Declare a DeviceAddress
DeviceAddress deviceAddress;

//In your setup routine do
sensors.getAddress(deviceAddress, index);
//Set the resolution to 9/10/11/12 bits
sensors.setResolution(deviceAddress, 9);

//In your loop change
gw.send(msg.setSensor(i).set(temperature,1));
// to
gw.send(msg.setSensor(i).set(temperature,2));

Just for information, remember that the stepsize in 12bit = 0.0625 °C, so don't expect to see temperature readings like 12.50, 12.51, 12.52, ...

[Yveaux]

@Totche said:

DS18B20

From the datasheet:
"It has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C."

There's not much sense in reporting more then 1 decimal, when the sensor is only accurate up to ±0.5°C .

[ericvdb]

@Yveaux ,

not entirely true, read a bit further in the datasheet:

The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively.
The default resolution at power-up is 12-bit

[Yveaux]

@ericvdb Resolution and accuracy are not the same! But if you're only interested in resolution, your solution will work just fine.

[m26872]

Agree with @Yveaux. The only situations I can see the full resolution to be useful is when one examine the accuracy or calibrate its output (e.g. offset).

Accuracy like 0.01 C would require some high class Pt100.