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ds18b20 discussion notes

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(Note: I was recommended to ask here, I’m not sure if there is a way to link my question to both SE’s)

I am looking to create a complete temperature humidity sensor system with 72 DS18B20 sensors. I am aware that each sensor receives it’s own unique identifier and you are able to daisy chain them together. The problem that I am running into is that I am unable to find any DS18B20’s that come pre-wired with either a RJ-11 or RJ-45 or similar output. Any recommendations on simplifying the sensors so that I can connect up to 72 or more sensors without having to crimp.

Closest part I could find is: https://www.dx.com/p/waterproof-ds18b20-temperature-sensor-with-adapter-module-for-arduino-2068262?tc=USD&ta=US&gclid=CjwKCAjwtajrBRBVEiwA8w2Q8M3cT5tqq_wZDYELYFuKgjfEyXfyiOpyokeLUyEyx4vutvJ4mRPJchoCsIsQAvD_BwE#.XWp31lNKjdQ

Unfortunately it seems the break out board with the step-up resistor only takes in one sensor. I’m unaware how I would have several put together.

Any recommendations would be appreciated.

put on hold as off-topic by Chris StrattonElliot AldersonDave Tweed Aug 31 at 15:00

This question appears to be off-topic. The users who voted to close gave this specific reason:

If this question can be reworded to fit the rules in the help center, please edit the question.

  • Whoever suggested you ask here was mistaken, as purchase recommendation / part to buy questions are off topic here. You can certainly find someone to make custom assemblies as a premium service but you may just want to spend a long day creating enough of a setup to validate the idea – there are many potential practical issues that may call the whole idea into question. Also beware grey market parts that seem to take longer than specified to convert and produce offset readings. – Chris Stratton Aug 31 at 14:18

 

 

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DS18B20 Temperature Sensor RJ-x

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I am looking to create a complete temperature humidity sensor system with 72 DS18B20 sensors. I am aware that each sensor receives it’s own unique identifier and you are able to daisy chain them together. The problem that I am running into is that I am unable to find any DS18B20’s that come pre-wired with either a RJ-11 or RJ-45 or similar output. Any recommendations on simplifying the sensors so that I can connect up to 72 or more sensors without having to crimp.

Closest part I could find is: https://www.dx.com/p/waterproof-ds18b20-temperature-sensor-with-adapter-module-for-arduino-2068262?tc=USD&ta=US&gclid=CjwKCAjwtajrBRBVEiwA8w2Q8M3cT5tqq_wZDYELYFuKgjfEyXfyiOpyokeLUyEyx4vutvJ4mRPJchoCsIsQAvD_BwE#.XWp31lNKjdQ

Unfortunately it seems the break out board with the step-up resistor only takes in one sensor. I’m unaware how I would have several put together.

Any recommendations would be appreciated.

 New contributor
  • 1
    Try asking this in the “Electrical Engineering” stack exchange group. – MatsK Aug 31 at 13:44
  • There are a couple of DS18B20 sensors of which only the waterproof probe with a long connecting wire is awkward to daisy chain together. All others, whether single chip through hole, small breakout with no wire or short wires, are easy to daisy chain or star like. It is only that you did to do a little bit of soldering, of if you like use a breadboard for experimentation, then change to a small prototyping board later. You can find photos of three different types of connections in my answer referred below. – tlfong01 Sep 1 at 8:11   

1

(1) I am not sure if you can daisy chain 72 DS18B20s using only one Rpi GPIO pin. My experience is that it is OK connecting 16 sensors to one GPIO pin and so 64 sensors on 4 pins. You need to remove the pull up resistor on all except one module on one bus. But even so, too many sensors on one 1-Wire bus still seems not very stable. You might like to see my sensor wiring photos and a fully debugged python 3.7.3 testing program:

Connecting 64 DS18B20 Sensors

(2) My DS18B20s are prewired to a popular cheapie 3 pin keyed connector, so you don’t need to do any RJ11 style crimping. You need to DIY simple signal routing breakouts to do star or daisy chain connections.

(3) I have tested my config for Rpi3B+ and also Rp4B, but with wires only about 60 cm long. I have not tested daisy chaining too many devices. I read that you need to use CAT5 like twisted pair cable for very long wires. You may find references in my answer manufacturer’s app notes on what extenders and buffers to use for very long wires.

(4) So far I only found one driver, python3-w1ThermSensor-1.0.5 good for Rpi3B+ and Rpi4B. Many other old drivers are for jessie only and do not work for stretch or buster.

  • thanks for linking to that it helped spawn some great ideas for experimentation. Do you by any chance have a parts list of all arts you used? Not to push it but with pics? Mainly looking for links to the raspberry pi model used, the green board you used to connect the ds18b20s to (not sure the name of the board). Also the ds18b20s. I’ve been suggested that many aftermarket ds18b20s have slightly off readings. In the environment I’m working with I need accurate readings. Thanks in advance. – Philoxopher Sep 1 at 9:29
  • 1
    I am using DS18B20 for home automation, so 0.1 degree C accuracy is OK for me. You might like to read the following for more details about DS18B20 accuracy. (1) ADC in Digital Temperature Sensor DS18B20 electronics.stackexchange.com/questions/94516/…, (2) And I usually google AliEXpress “DS18B20”, “DHT22” or “Prototyping boards” etc, then goto to TaoBao where I can get same thing and almost always even cheaper. The CJMCU stuff are usually more trustworthy than eBay. Of course you should search Element14 for serious projects. – tlfong01 2 days ago   
  • what is the 3 pin breakout board you are using. I am unable to find it anywhere. Thanks. – Philoxopher 2 days ago
  • 1
    I searched my TaoBao purchase orders and found the following: (1)item.taobao.com/… (2) item.taobao.com/… (3) item.taobao.com/… (4) item.taobao.com/… (5) item.taobao.com/…. – tlfong01 2 days ago    
  • would it be possible to contact you directly for consulting services regarding this project? – Philoxopher 13 hours ago
  • @Philoxopher, Ah, let me see. You might like to include in your forum profile your email, blog, or github address. I would let your know if I can help. Cheers. – tlfong01 12 hours ago   

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