Memorial day is 05/25/2015 – Orders will ship out on May 26th. There will not be any deliveries or shipping on Monday. Any order placed after 11am ET on Friday May 22nd will not start to ship out until Tuesday May 26th.

DHT22 / RHT03
Moderators: adafruit_support_bill, adafruit

Forum rules
Talk about Adafruit Raspberry Pi® accessories! Please do not ask for Linux support, this is for Adafruit products only! For Raspberry Pi help please visit: http://www.raspberrypi.org/phpBB3/

DHT22 / RHT03

by Worcester on Sun Sep 09, 2012 6:40 pm

Been trying to get the RPi to read the output from the DHT22 using the ciruit and code here:
http://learn.adafruit.com/dht-humidity- ... cs-logging

However I'm getting nothing back from the port, I've posted infor on the RPi forum, ( http://www.raspberrypi.org/phpBB3/viewt ... 37&t=15755 ) however still waiting for answers.

1) Yes I have a Pull up resistor in Place,
2) Yes I have an Oscilloscope,

Using the code in
$ sudo ./Adafruit_DHT, the responce I get back is:

Code: Select all | TOGGLE FULL SIZE
pi@raspberrypi ~/Adafruit-Raspberry-Pi-Python-Code/Adafruit_DHT_Driver $ sudo ./Adafruit_DHT 22 4
Using pin #4
Data (0): 0x0 0x0 0x0 0x0 0x0


Here are the oscillsope traces:
https://picasaweb.google.com/1132605127 ... directlink

So clearly the pin goes low and then comes back up high, though the routine doesn't appear to pul back the data

I've tried different pins - no different, and I;ve tried other routines to do other things using the same pin and they work OK.

I've tried 5V and linked both pins 3 and 4 to gnd (see comments here: https://www.sparkfun.com/products/10167 )

Any ideas?

Thanks, Worcester
Worcester
 
Posts: 1
Joined: Sun Sep 09, 2012 6:26 pm

Re: DHT22 / RHT03

by Dwali on Mon Sep 24, 2012 1:24 am

I'm having the same issue with the AM2302. Glad I'm not alone. I've found no solution to this problem yet.
Dwali
 
Posts: 7
Joined: Sun Sep 23, 2012 4:55 pm

Re: DHT22 / RHT03

by cynikal on Mon Sep 24, 2012 1:58 am

Ditto,

I've been running this thing in a loop (sleep 3 seconds before polling), and in the last 5 minutes it's answered me maybe twice.. what gives??
cynikal
 
Posts: 7
Joined: Sun Sep 09, 2012 9:38 pm

Re: DHT22 / RHT03

by cynikal on Mon Sep 24, 2012 2:31 am

Found the solution at the bottom:

http://www.raspberrypi.org/phpBB3/viewt ... 5&p=179399

basically it involves changing the timing 100 to 500000 and recompiling. It's still not working 100% (e.g. it still returns 0 data) but it's like non-responsive once in 20 times instead of it working once every 20 times
cynikal
 
Posts: 7
Joined: Sun Sep 09, 2012 9:38 pm

Re: DHT22 / RHT03

by outspoken on Mon Sep 24, 2012 8:54 am

How did you recompile it?

When I try I get:

Code: Select all | TOGGLE FULL SIZE
gcc -c -o Adafruit_DHT.o Adafruit_DHT.c -std=c99 -I. -lbcm2835
Adafruit_DHT.c:24:21: fatal error: bcm2835.h: No such file or directory
compilation terminated.
make: *** [Adafruit_DHT.o] Error 1


I can't seem to find bcm2835.h

EDIT: found it, google hides this page quite well - http://www.open.com.au/mikem/bcm2835/index.html
outspoken
 
Posts: 2
Joined: Tue Sep 18, 2012 8:23 pm