Read DHT 11 temperature sensor and hum...



  • i try to read data from DHT 11 sensor
    my file dhttest.py looks like

    from machine import Pin
    from machine import UART
    import DHT
    dht_pin=Pin('G4', Pin.OPEN_DRAIN)
    dht_pin(1)
    
    temp, hum = DHT.DHT11(dht_pin)
    # temp = temp * 9 // 5 + 320   # uncomment for Fahrenheit
    temp_str = '{}.{}'.format(temp//10,temp%10)
    hum_str = '{}.{}'.format(hum//10,hum%10)
    
    # Print or upload it
    print(temp_str, hum_str)
    

    but when i do
    execfile('dhttest.py')
    result is
    280.5 280.5
    but second execution
    execfile('dhttest.py')
    cause halt exception

    >>> execfile('dhttest.py')
    280.5 280.5
    >>> execfile('dhttest.py')
    Guru Meditation Error: Core   0 panic'ed (Interrupt wdt timeout on CPU0)
    Register dump:
    PC      :  400d277d  PS      :  00060634  A0      :  80082d94  A1      :  3ffdc2a0  
    A2      :  0006062f  A3      :  00000245  A4      :  00000001  A5      :  00000001  
    A6      :  00000000  A7      :  3ffb0154  A8      :  00000001  A9      :  3ffdc280  
    A10     :  3ffc4bf4  A11     :  0000012c  A12     :  00000122  A13     :  00000000  
    A14     :  00000003  A15     :  00060223  SAR     :  00000004  EXCCAUSE:  00000005  
    EXCVADDR:  00000000  LBEG    :  4000c2e0  LEND    :  4000c2f6  LCOUNT  :  ffffffff  
    CPU halted.
    

    code of dht.py is here
    dht post

    please help with this



  • This post is deleted!


  • I got into the same issue with this DHT11 sensor.
    I wonder if it still has to do with the threading issue as mentioned here.

    Secondly, why is the call to dht_pin(1) required?
    If I get it right, this writes a value of 1 to the pin?

    *edit
    Even without any sensor connected, the code still returns a fixed 28.05.



  • Hello.

    I bought a grove sensor which contains DHT22 (now called AM2302) and i tried the code mentioned here and it does return 280.5 without crashing but nothing else. Does anyone know how to actually read the sensor data? or point me to the right direction?

    I am using a LoPy by the way.

    Thanks


  • Pycom Pyoneers

    Hi @livius,

    We released a new firmware with updates in stability that i think might help you with your issue, please download it at
    https://www.pycom.io/support/supportdownloads/
    and follow the instructions

    Best,
    Roberto



  • With todays firmware it does not crash :)


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