ESP8266 Community Forum

- Mon Feb 15, 2016 1:54 pm #41186 I've actually been able to boot up the module now. When I desolder the volage line to the 2 ds18b20 sensors, the voltage drop to 1.8v is gone and I am able to boot up to module and flash firmware into it. I don't yet have the capacitors (ordered from aliexpress, so will take a while), but I was wondering if that would solve this issue, or could one of my ds18b20 sensors be faulty?

I also noticed that the LM1117 gets very hot during operation. Is that normal and is it a good long-term solution for the power source, or are there better ways?

- Mon Feb 15, 2016 4:26 pm #41192

When I desolder the volage line to the 2 ds18b20 sensors, the voltage drop to 1.8v is gone and I am able to boot up to module and flash firmware into it. ... could one of my ds18b20 sensors be faulty?

I also noticed that the LM1117 gets very hot during operation. Is that normal and is it a good long-term solution for the power source, or are there better ways?

I'm fairly certain those DS18B20's are wired up back to front...in which case they will probably be as hot as the regulator. I've managed that trick in the past - but they did survive the experience!

Stockport, UK

- Thu Feb 18, 2016 1:35 pm #41389 Well PhilHornby, you're actually right. After improving my schema, adding 10k resitors between the en pin and 3.3v and adding another 10k resistor between gpio15 and gnd, I still had the same voltage loss issue.

I then wired both data pins of the ds18b20 to gpio5, and added a 4.7k resistor between the data lines and 3.3v, as suggested in this excelent tutorial: http://www.tweaking4all.com/hardware/ar ... re-sensor/

Unfortunately, still the same problem. I then soldered loose one of the ds18b20 sensors, and all of a sudden my problem was gone. I was starting to think my Chinese friends made a mistake with the wire colors of the sensor )it´s one of those waterproofed ones, like this) and soldered the sensor back on, this time with the vcc and gnd wires the wrong way around.

what do you know, it worked! I can now read the temperatur from both sensors!

so if anyone ever encounters this issue, there are ds18b20 sensors around with this kind of wiring:

yellow: data
black: vcc
red: gnd

- Fri Feb 19, 2016 6:38 pm #41486

Well PhilHornby, you're actually right...
...it´s one of those waterproofed ones

In that case, it was a lucky guess

If I'd known you were using the waterproofed ones, I wouldn't have thought of it - but the loose DS18B20s are very easily plugged into a breadboard the wrong way round. You tend to spot that mistake quite quickly because you can feel the heat coming off them - but it won't be anything like as obvious with the waterproof ones.

Stockport, UK