DHT22 and PIC18F25K22

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  1. #1
    Join Date
    Sep 2005

    Default DHT22 and PIC18F25K22

    Hi I'm using a PIC18F25K22 to drive 2x DHT22.
    I found here some code working on PORTB.4
    The other DHT is connected on PORTB.2 and... not working
    I tried to exchange the 2 DHT22 without success. The 2 DHT22 are working fine on portB.4
    Name:  dht22.JPG
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    sequence is:
    TRISB.2 = 1 'input
    my program... then
    TRISB.2 = 0 'output
    PORTB.2 = 0 'low

    With my DSO, I can see something strange. It takes more than 1mSec to become low (see curve)
    Name:  elecdif.jpg
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    This is only on PORTB.2 !
    May be you have an idea ? (I'm using PBP2.60)
    Last edited by harryweb; - 13th November 2017 at 21:46.

  2. #2
    Join Date
    Oct 2009

    Default Re: DHT22 and PIC18F25K22

    Have a read of this thread http://www.picbasic.co.uk/forum/showthread.php?t=19975

    The excellent library file allows multiple sensors to be used (I have four running to monitor temperature and humidity in my reptile enclosures)

  3. #3
    Join Date
    Sep 2005

    Default Re: DHT22 and PIC18F25K22

    Hi Scampy,

    Yes this code is well done... But I'd like to use my own...
    I tried another PIC (18f2520) = same pb, changing pullup resistors, capacitors...
    I just found the problem... It's an hardware problem. Can't see it without binoculars... soldering to ground on PCB was not good
    Thank you.
    Name:  soudure.JPG
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