1-wire

[PassivPluss]

Hi
I have installed 1wire sensors in my ventilastion system to measure temperatures and make a heat recovery curve.

I'm using DS18B20.

When looking at these sensors online i found the following info:
OPERATION—MEASURING TEMPERATURE

The core functionality of the DS18B20 is its direct-to-digital temperature sensor. 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.

When I look at the temperatures measured by the LM i get 0,25-0,5C jumps when reading. Is it possible to get this reading more accurate? I would like to have 0.125 or 0.0625 options as well?

PassivPluss

[admin]

Right now we are using 10-bit resolution in order not to block the bus for too long as increasing the resolution causes the measurement to take longer time to finish. Value will always be slightly unstable, this is just how the sensor works. You can increase the accuracy by oversampling: reading several values in a row and calculating the average.

You can also read full resolution temperature value from a script like this:

Code:

require('ow')
value = ow.readfile('SENSORID', 'temperature', true) -- third argument will force a new conversion

[buuuudzik]

I had some questions about 1wire:
- what is the maximum length of the bus(maybe something from practice)?
- how much sensors I can connect to LM4?
- can I use some 1wire outputs?

[admin]

Guidelines for Reliable Long Line 1-Wire Networks
https://www.maximintegrated.com/en/app-n...mvp/id/148

Number of sensors depends on many factors like what kind of sensors they are, how long the line is, are sensors bus-powered or have a dedicated 5V supply etc.

For outputs we have this product that might suit your needs:
http://openrb.com/1-wire-2-universal-io/

[buuuudzik]

What do you think about switching 1wire lines(description is in the Dallas manual). What will be the LM reaction? E.g. I have 2 floors and 1st second I will have connected to the 1wire port 1 floor and 2nd second 2 floor. This could be good end very cost efficient. But then probably I can't use the LM 1wire manager but some special script.

This would be a good new feature in LM

And also I have a question about LM5(with a new CPU): Can I integrate 1wire via USB converter?