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RPi is working fine with 10 1-wire temperature sensors, but I need to connect 20.

  • Can you post how you are connecting them and what issue you encounter when trying to connect more than 10? According to this Adafruit posting it is possible to connect multiple DS18B20 sensors in parallel, but it doesn't specify if there is a limit. – HeatfanJohn Nov 11 '13 at 20:38
  • Add this line of code to: /etc/modules wire max_slave_count=20 – user10535 Nov 12 '13 at 15:50
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See Guidelines for Reliable Long Line 1-Wire Networks

Two simple terms describe measurements that are critical to 1-Wire network performance: radius and weight.

  • The radius of a network is the wire distance from the master end to the most distant slave. It is measured in meters.

  • The weight of a network is the total amount of connected wire in the network. It is also measured in meters.

For example, a star network configuration with three branches of 10m, 20m, and 30m would have a radius of 30m (i.e., the distance from 1-Wire master to the furthest slave) and a weight of 60m (i.e., the total length of wire in the network, 10m + 20m + 30m).

In general, the weight of the network limits the rise time on the cable, while the radius establishes the timing of the slowest signal reflections.


Testing has shown that unswitched star-type network topologies (i.e., those with several branches diverging at the master) are the most difficult to make reliable.

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I would suggest using a i2c 8 channel 1-wire rpi hat.
http://www.sheepwalkelectronics.co.uk/product_info.php?cPath=22&products_id=67

It performs tons quicker then the bitbangging way the pi does it. I would also recommend using owfs (One Wire File System). Which essentially does the same thing as what Raspbian has done in creating a directory where your 1-wire devices are. http://owfs.sourceforge.net/index_old.html

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there is a limit on w1 wire module to 10 sensors.

I find this information but i don't test it for the moment

visit this post here

If you or anyone else are still wondering how to attach more than 10 devices, just load the module with the following argument:

modprobe wire max_slave_count=15

or in /etc/modules with simply

wire max_slave_count=15

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