@paulstoffregen Hi Paul, how is it going on this project? Are we likely to see boards in the coming months? There is some nifty stuff I am looking forward to using it for.
Well, it depends. Are the DHT22 reliably all twos-complement? And converse for the DHT11? Etc. And, besides number of bytes and sign versus 2's, are the devices different in any other way?
It seems like the...
Of course, and perhaps that goes for any of them. Hence it seems like a good idea to add a parameter (perhaps in the class intializer) to select it manually.
Yep. and it turns out to be very useful. How do we (or do we), get this into the code for the library? Also, I notice there are a few other cases where it assumes sign-magnitude. I can fix the other cold stage and...
@el_supremo
Here is a revision for your DHT.cpp to fix the problem for the DHT22. I tested it just now, it seems to work.
Aside, I read the data sheet, it does seem confusing on this point.
float...
It seems to be a twos-complement vs sign-magnitude problem, el_supremo worked it out here, https://forum.pjrc.com/threads/70344-DHT22-checksum-error-for-negative-temperatures#12
@el_supremo, That is actually correct!!! (twos complement vs sign magnitude)
-4.9C is what I read previously with a thermistor and DVM.
I apologize (and regret) that I didnt parse the fine print sooner. I...
@el_supremo I have to get the experiment started now, its getting late and i need it to finish by a certain time. But, fortunately, I do have another cold stage with another DHT22, so i'll get that started and...
I'm having problems with the DHT22 for temperatures below 0C, it returns temperatures around -3272C, for any setting of the third parameter, from 6 to 80,
For temperatures above 0C it works fine with any setting in...
@manitou and @el_supremo So, still not working.
The Adafruit DHT-sensor-library reports a temperature of -3272.4C.
An impressive and stunning repudiation of the third law of thermodynamics.
(Temperatures...
@manitou and @el_supremoe Thank you, that makes sense now, I'll try it. It raises another question, why the incompatibility isnt flagged in the development environment.
If I thought it was a hardware problem, then trying another library might be a good way to check. But, I have two of these sensors, so maybe I'll just try the other one first.
I suspect it is not hardware. Hence...
Hi,
I am using the DHTlib with a DHT22 and a Teensy 3.2. The code works okay for temperatures greater than 0C. However, when the temperature drops below 0C, it returns a checksum error. The datasheet for the...
Doctorate in Chemistry and Physics, former faculty in Materials Science at a big ten school, scientist in x-ray diffraction, spectroscopy and instrumentation at a National Lab. Currently working on lasing, lighting and quantum information applications in organic semiconductors.
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