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Intermittent loss of one-wire sensors

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(@trystan-williams)
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Joined: 1 year ago
Posts: 10
Topic starter  

Hardware: ESP32 w/ Firmware v. 45. 

I'm seeing BruControl appear to lose track of one-wire sensors every few days or so of continuous running. I have two sensors attached, sometimes only one is lost but more often both go down (BruControl interface shows --- for the temp reading). Other components are still functional though, as I can still manipulate pumps etc. Power cycling the ESP32 fixes the issue. 

Any idea what may be happening? Let me know if there is additional info I can provide to debug. As a temporary mitigation method, is there a way I can detect a null reading / disabled sensor in a script?   


   
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(@pbruno3)
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Joined: 6 years ago
Posts: 341
 

Hi there. Would be helpful to know more about your system. Pictures, schematics, or specific details would help us give advice. Also, does the problem fix itself, or is it such that once the temperature reading drops, it stays dropped?

Typically, power issues and noise cause the issue. A few tips:

  1. Reduce wire length. Shorter wires are less prone to noise.
  2. Avoid routing near noisy devices. For example, run wires away from high voltage solenoids, motors, power supplies, etc.
  3. Shield wires or use shielded wire, with the shield tied only to ground back at the interface. Twisted wires may improve performance too.
  4. Use a ground star configuration (all grounds to one point), and consider tying star to AC earth.
  5. Use a 2.2k pull-up resistor, and a quality power supply (e.g. not a phone charger).

You can use the script to identify a reading that is out of an expected range, then take action. I would suggest NOT power-cycling the ESP32 - you can use the %3 control code to reset the 1-wire bus.


   
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(@trystan-williams)
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Joined: 1 year ago
Posts: 10
Topic starter  

Thanks for the script workaround! That should 'fix' the problem until I can stabilize the panel hardware. 

I have the pull-up resistor in place and a good power supply. I did notice this seems to happen when a pump kicks on, not every time, but there's a correlation. I'm powering both temp sensors from the 3.3v pin on a ESP32. When the pump kicks on, I wonder if there's a short power fluctuation that starves the sensors. 

I'll work on getting a schematic together. Not my wheelhouse so it will be a while 😉   


   
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(@pbruno3)
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Joined: 6 years ago
Posts: 341
 

What kind of pump (AC/DC?). How is it powered... from a UniShield, through a relay, etc.

Sometimes the EMI from an inductive load (like a motor, solenoid, etc.) can cause these issues. If you provide more details or pics, that might help. Can email them if easier.


   
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