Temperature Sensor DHT11/22 via GPIO using Adafruit Libraries

Lafuture · May 6, 2018 at 9:22 PM

Hey,

i am trying to connect a DHT11/22 temperature sensor to my Libreelec/RPi2 using the GPIO connectors to get current room temperature (and humidity).

I have installed the "Adafruit Libraries" Addon from the Official "LibreELEC" Addon repository. This includes "Adafruit_DHT" Libraries that are intended to do that.

But unfortunately i am struggeling with using this Libraries properly.

I tried a simple python example script to put out the current temperature:

Script source: adafruitdht.py

I added these lines to load the DHT libraries:

Python

libPath = '/storage/.kodi/addons/virtual.adafruit-libraries/lib/'
if not libPath in sys.path: sys.path.append(libPath)
import Adafruit_DHT

But still only get errors

Bash

/storage#> python ./AdafruitDHT.py 22 4
Traceback (most recent call last):
File "./AdafruitDHT.py", line 43, in <module>
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/common.py", line 90, in read_retry
humidity, temperature = read(sensor, pin, platform)
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/common.py", line 76, in read
platform = get_platform()
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/common.py", line 59, in get_platform
raise RuntimeError('Unknown platform.')
RuntimeError: Unknown platform.

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Are there some docs i can read regarding Libreelec and the Adafruit Libraries? (I have found nothing so far)

Are the Adafruit Libraries intended to be used from the commandline?

Or do i need to call them from Kodi?

Are there any examples i can have a look at?

I appreciate any hint or Idea.

Thanks

Thomas

**inusasha** · May 7, 2018 at 8:21 AM

Hi Thomas,

good news first:

your code looks ok.

bad news:

this can be an problem in adafruit library itself. Is not the first library, with this kind of problem.

But i need more information, about your setup.

1. which LE version, you are running?

2. which RPi do you use?

3. output of `cat /proc/cpuinfo` from your RPi console

Bye,

Sascha

Lafuture · May 8, 2018 at 7:53 AM

Hey Sascha,

sorry, missed the notification of your reply

Libreelec is the latest official Version: LibreELEC (official): 8.2.5 (RPi2.arm)
Board is a RPi2 / B
cat /proc/cpuinfo puts out:

Code

processor       : 0
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 38.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

processor       : 1
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 38.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

processor       : 2
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 38.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

processor       : 3
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 38.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

Hardware        : BCM2835
Revision        : a01041
Serial          : 00000000...

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**inusasha** · May 8, 2018 at 8:18 AM

I updated the DHT library to the newest version.

Can you try the new addon: virtual.adafruit-libraries-8.2.102.zip

Sascha

Lafuture · May 8, 2018 at 10:11 AM

Code

/storage#> python ./AdafruitDHT.py 22 4
Temp=21.6*  Humidity=54.4%

This is ... woah! This makes me sooo happy

THANK YOU!!

Will this updated library go into the official repo so all users will receive it?

**inusasha** · May 8, 2018 at 10:25 AM

Of course.

But will take same days. I has to test some other devices.

Sascha

Lafuture · May 8, 2018 at 10:43 AM

Just to have mentioned it: the retrieval seems quite slow:

Code

time python ./AdafruitDHT.py 22 4
Temp=21.7*  Humidity=54.4%
real    0m 8.38s

But i have no experience if this is faster when using s/th like raspbian.

At all this is no problem for my needs

Now i can order some more sensors

Thanks again for your fast help!

myrpi · January 21, 2021 at 2:39 PM

Hello,

I am having almost the same problem with bad Adafruit Libraries on LE 9.2.4 running on RPI3 and RPI4.

Traceback (most recent call last):
File "./dht.py", line 42, in <module>
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/common.py", line 94, in read_retry
humidity, temperature = read(sensor, pin, platform)
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/common.py", line 80, in read
platform = get_platform()
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/common.py", line 55, in get_platform
from . import Raspberry_Pi_2
File "/storage/.kodi/addons/virtual.adafruit-libraries/lib/Adafruit_DHT/Raspberry_Pi_2.py", line 22, in <module>
from . import Raspberry_Pi_2_Driver as driver
ImportError: cannot import name Raspberry_Pi_2_Driver

If I install old library from Sascha I don't have any more python error but I don't get any reading from DHT11:

Failed to get reading. Try again!

Any ideas ?

Thank you

myrpi · January 21, 2021 at 11:35 PM

I tested the DHT sensor on latest Raspberry Pi OS and it is OK, I can get the values from it.

Upgraded to latest stable LE 9.2.6 both RPI3+ and RPI4 and I have the same problems as before.

It is a problem with latest Adafruit libraries from LibreELEC.

Any chance for a fix from LE team ?

Thank you