DS18B20 not recognized

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Ritter_Runkel
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Joined: 07 Mar 2020, 10:14

DS18B20 not recognized

#1 Post by Ritter_Runkel » 07 Mar 2020, 10:28

Dear Fans of ESPEASY,
I need some help regarding the usage of my DS18B20 at ESPeasy.

Problem description:
- adress of DS18B20 is not visible after configuration of the device independent from the chosen GPIO/Dx

I have the following frame conditions / did the following doublechecks:
- Wemos D1 Mini plattform
- ESPEasy Version "normal" 20200222 running on Wemos D1 R1 Mini
- configured devices SR04 board connected to D6+D7 is working
- DS18B20 tried on different Pins (D0,D8,D1)

Doublechecks already done:
- DS18B20 is working with the same cables at an NodeMCU (self compiled ESPeasy from 2019)
--> so sensor must be working, no cabling problems

Strange thing - there is also no output at the serial monitor regarding the 1wire plugin... I see everything else (Wifi, SR04,.....) but no line regarding 1 wire.

Are there any ideas what can be the problem?

Many thanks in advance for help!
//Erik

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grovkillen
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Re: DS18B20 not recognized

#2 Post by grovkillen » 07 Mar 2020, 11:25

Do you have a pull-up?
ESP Easy Flasher [flash tool and wifi setup at flash time]
ESP Easy Webdumper [easy screendumping of your units]
ESP Easy Netscan [find units]
Official shop: https://firstbyte.shop/
Sponsor ESP Easy, we need you :idea: :idea: :idea:

Ritter_Runkel
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Joined: 07 Mar 2020, 10:14

Re: DS18B20 not recognized

#3 Post by Ritter_Runkel » 07 Mar 2020, 12:35

Hi,
I don’t use a pull-up.
It works also without pull-up at the node-mcu.
But I can try one.

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grovkillen
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Re: DS18B20 not recognized

#4 Post by grovkillen » 07 Mar 2020, 22:12

Well, our code is based on pull-up. Others might not.
ESP Easy Flasher [flash tool and wifi setup at flash time]
ESP Easy Webdumper [easy screendumping of your units]
ESP Easy Netscan [find units]
Official shop: https://firstbyte.shop/
Sponsor ESP Easy, we need you :idea: :idea: :idea:

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ThomasB
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Re: DS18B20 not recognized

#5 Post by ThomasB » 07 Mar 2020, 23:09

DS18B20 tried on different Pins (D0,D8,D1)
D0 & D1 require a pull-up resistor when used with the DS18B20.
D8 GPIO15 is a boot pin. The ESP module has pull-down resistor on this GPIO. Do NOT install DS18B20 on this pin.
Pin map and precaution info:
https://www.letscontrolit.com/wiki/inde ... figuration

The DS18B20 pin's expected pull-up resistor is typically 4.7K ohms (connected to 3.3V). A lower value may be needed if using long wire leads or multiple sensors. If using a DS18B20 PCB module then inspect it to see if the required pull-up is already present. Only one pull-up is used regardless of the number of sensors on a shared bus, so remove duplicated pull-ups.
It works also without pull-up at the node-mcu.
The nodeMCU is a developer board. Perhaps you used a pin that already had a pull-up on it. Or maybe the internal weak pull-up was blessed with a low enough value that it satisfied the DS18B20. In other words, your success was because you won the data I/O lottery.

EDIT: If you continue to have problems with detecting the DS18B20 then it could be due to Mega-20200222 you've been using. This version has caused DS18B20 detection problems on one of my nodes. So, please try the very latest release (Mega-20200305 or higher).

- Thomas

Ritter_Runkel
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Re: DS18B20 not recognized

#6 Post by Ritter_Runkel » 09 Mar 2020, 20:41

Thanks for your time Thomas to answer my question.

I solved the issue with an additional DS18b20 in parallel. Both without pull-up resistor.
This brought some more voltage to the wire and had a similar effect like a pull-up.
At the end I have some more data ;-)

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