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I have a DS18B20 temperature sensor connected to a Raspberry Pi 3b+. I created a simple Python program to monitor the temperature of my heating system. The program works very well....when it works...sometimes it stops and when I check the raspberry pi, the sensor in /sys/bus/w1/devices is no longer there.

I noticed that the voltage between DQ and GND, when the sensor is correctly detected by the raspberry, is equal to 5V, while when it is not detected, the voltage drops to 1.3V. it's the only strange thing I've noticed and it persists even when changing raspberry and changing probe. I even changed the cable.

I have other 3 systems like this one that works perfeclty with the same configuration.

On the raspberry I use a board, this board https://sferalabs.cc/product/iono-pi-board/

Luca Scalvi
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  • 5V might fry Rpi. except is Rpi5. – tlfong01 Jan 13 '24 at 13:06
  • I have a board attached to the Rpi from sferalabs and the sensor is connected through the board. Notice that I have other 3 systems like this one that works perfeclty with the same configuration. – Luca Scalvi Jan 13 '24 at 15:34
  • The DS18B20 requires a pull-up resistor (between middle/data pin and Vin pin), is the resistor that you are using the same in all configuration? – Matteo Ferla Jan 13 '24 at 17:36
  • "I created a simple Python program" which you haven't listed. You posted vague comments about DQ but otherwise failed to explain what is connected or what Device Tree settings are used. – Milliways Jan 13 '24 at 21:18
  • The pull-up resistor is the same on all configurations. It's provided by the board itself – Luca Scalvi Jan 13 '24 at 21:58
  • the question has nothing to do with raspberry config, python or wiring, so I haven't given any further details on the matter. As indicated this hardware/software setup has worked flawlessly for years in 3 separate systems. Unfortunately, things went differently here and I would like to understand why, perhaps from someone who has had the same problem. I indicated the only anomaly found: the voltage drop – Luca Scalvi Jan 13 '24 at 22:34
  • See Tour to see how this site works and How do I ask a good question? – Milliways Jan 13 '24 at 22:52
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    @Luca Scalvi, I vaguely remember that I had a similar problem, but that was 4 years ago. You might find the following answer useful: https://raspberrypi.stackexchange.com/questions/100203/ds18b20-temperature-sensor-rpi-3-4-driver-wiring-detection-and-python-progr/100244#100244 – tlfong01 Jan 14 '24 at 07:48

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I'll do more testing but for now I'm pretty sure I've figured out the problem. The power supply. I assumed it was good since it was sold to me by the same company as the board. I changed the power supply and the problem no longer occurred. I knew it wasn't a python programming problem

Luca Scalvi
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