I am trying to connect a DS18B20 to a Esp32 Thing plus. Having no luck with a 3.3V connection to the DS18B20 I moved for a 5V connection using the Sparkfun Logic Level Converter - Bi-Directional module.
I connected the DS18B20 to HV4 via a 10kOhm pull-up(since logic level converter also has a 10kOhm pull-up ) and the LV4 to GPIO4 on the ESP32. LV is connected to 3.3V and HV to VUSB. The DS18B20 is also connected to VUSB. I have measured the voltages everywhere and it matches what it should be.
Using a oscilloscope(Ch1 - HV4, Ch2 - LV4) I can ese some communication but the “lows” are to high to be accepted as a low! What could be wrong?
I have built the same with ESP32 thing. Using the DS18X20 example from the onewire library ( https://www.pjrc.com/teensy/td_libs_OneWire.html) and connected to GPIO5. No problems, worked in one go.
Below is a picture of the overview and in the attached DS18.jpeg are the scope signals. It did not make any difference for me whether the extra 10K was included or not.
Thanks for testing! Seeing your result I switched the DS18B20 to see if the sensor were bad. Same result.
Did some more digging using google and found that there could be a impedance problem(I forgot to mention in my first post that the DS18B20 I use is a waterproof version with a 1 m cable). When connecting a 100R in series with the sensor things looked better(attached 2.jpg) but not good enough…
When disconnecting the sensor and just looking at HV4 and LV4(attached 3.jpg) it is clear that the problem is the sensor and not the sparkfun products. I will try and find some other supplier of the sensor.
weird… As you might have seen from the picture I too have a DS18B20 waterproof + 1 m cable. It is known that this sensor comes in different quality/response packages. Maybe also try to use the same program as I did and connect to a different pin ( I used digital GPIO5).
