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DHT22 Temp sensor on Pi 4 #493

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opened 2022-10-15 07:04:32 +01:00 by pman92 · 3 comments
pman92 commented 2022-10-15 07:04:32 +01:00 (Migrated from github.com)
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Hey guys,
I've recently changed from using a pi 3b+ to a pi 4b.
I previously had a DHT22 temp sensor working with the enclosure plugin on the 3B+. Its now connected the same (to GPIO 4) on the 4B but I cannot get it to work.

  1. I have SSH'ed and installed the adafruit-circuitpython-dht and libgpiod2 as described in the enclosure plugin readme.
  2. I have tried disabling "use SUDO" in enclosure plugin advanced settings (as I had to do that to get it working on the 3B+, but it made no difference on the 4B).
  3. I have tried the adafruit sample code, and get the following:
    pi@octopi:~ $ python3 dht_simpletest.py Traceback (most recent call last): File "dht_simpletest.py", line 5, in <module> import board File "/home/pi/.local/lib/python3.7/site-packages/board.py", line 44, in <module> from adafruit_blinka.board.raspberrypi.raspi_4b import * File "/home/pi/.local/lib/python3.7/site-packages/adafruit_blinka/board/raspberrypi/raspi_4b.py", line 6, in <module> from adafruit_blinka.microcontroller.bcm2711 import pin File "/home/pi/.local/lib/python3.7/site-packages/adafruit_blinka/microcontroller/bcm2711/pin.py", line 5, in <module> from RPi import GPIO ModuleNotFoundError: No module named 'RPi'
Hey guys, I've recently changed from using a pi 3b+ to a pi 4b. I previously had a DHT22 temp sensor working with the enclosure plugin on the 3B+. Its now connected the same (to GPIO 4) on the 4B but I cannot get it to work. 1. I have SSH'ed and installed the adafruit-circuitpython-dht and libgpiod2 as described in the enclosure plugin readme. 2. I have tried disabling "use SUDO" in enclosure plugin advanced settings (as I had to do that to get it working on the 3B+, but it made no difference on the 4B). 3. I have tried the adafruit sample code, and get the following: `pi@octopi:~ $ python3 dht_simpletest.py Traceback (most recent call last): File "dht_simpletest.py", line 5, in <module> import board File "/home/pi/.local/lib/python3.7/site-packages/board.py", line 44, in <module> from adafruit_blinka.board.raspberrypi.raspi_4b import * File "/home/pi/.local/lib/python3.7/site-packages/adafruit_blinka/board/raspberrypi/raspi_4b.py", line 6, in <module> from adafruit_blinka.microcontroller.bcm2711 import pin File "/home/pi/.local/lib/python3.7/site-packages/adafruit_blinka/microcontroller/bcm2711/pin.py", line 5, in <module> from RPi import GPIO ModuleNotFoundError: No module named 'RPi' `
pman92 commented 2022-10-15 09:01:57 +01:00 (Migrated from github.com)
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I fixed the "no module found" error by running "sudo apt install python3-rpi.gpio".
However the sensor still doesn't work, I now get "DHT sensor not found, check wiring" from the adafruit test script.

The sensor is connected to GPIO4 (pin 7). Inside the script I have:
dhtDevice = adafruit_dht.DHT22(board.D4)
and have also tried:
dhtDevice = adafruit_dht.DHT22(board.D4, use_pulseio=False)

I fixed the "no module found" error by running "sudo apt install python3-rpi.gpio". However the sensor still doesn't work, I now get "DHT sensor not found, check wiring" from the adafruit test script. The sensor is connected to GPIO4 (pin 7). Inside the script I have: `dhtDevice = adafruit_dht.DHT22(board.D4)` and have also tried: `dhtDevice = adafruit_dht.DHT22(board.D4, use_pulseio=False)`
pman92 commented 2022-10-15 10:29:36 +01:00 (Migrated from github.com)
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Have got it working.
After finding this, I installed the following:
pip3 install sysv-ipc
And now the sensor is working fine in both octoprint and the test script.

I still require "use SUDO" to be disabled under advanced settings like I did with the 3B+. Which makes sense because if a run the test script as sudo it still says sensor not found.

Have got it working. After finding [this](https://lightrun.com/answers/adafruit-adafruit_circuitpython_dht-a-full-buffer-was-not-returned--try-again), I installed the following: `pip3 install sysv-ipc` And now the sensor is working fine in both octoprint and the test script. I still require "use SUDO" to be disabled under advanced settings like I did with the 3B+. Which makes sense because if a run the test script as sudo it still says sensor not found.
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burnerbmx commented 2023-07-03 00:49:39 +01:00 (Migrated from github.com)
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i had this issue but manged to get rounf that im using the dht11 sensor and its reading temp and humi but to dislaying the values on my octoprint

i had this issue but manged to get rounf that im using the dht11 sensor and its reading temp and humi but to dislaying the values on my octoprint
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Reference: Gandalf/OctoPrint-Enclosure#493
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