DHT22 - anyone got one working?

[uhclem]

I'd like to do some environmental monitoring with my BBB and want to use a DHT22. I have found a few examples online but have had no luck getting any to work.

Closest I've come to "working" is with this code:
https://github.com/lhuet/beaglebone-pro ... ster/DHT22

Note that it will not complile until Beagle_GPIO_dht22.cc has this library added:
#include <unistd.h>

Using the default pin of P8_3, I can get a nonsense output of "Temp = 0°C, Hum = 0%". If I change that to, say, P8_7, it returns nothing and "echo $?" gives "135" which is some sort of error. I am running the program as root.

I would contact the code author, but there's no obvious contact info on github and he's French speaking and I'm not.

I am following the DHT sensor tutorial for the Pi for wiring. I am powering the DHT22 from P9_3 (3.3v) and am using a 6.8k pullup resistor.

I will readily admit I am mostly an ATMEL C/C++ coder and very rusty with posix stuff. Also I am very new to the beaglebone and its GPIO config system. It could be I am missing something obvious or doing something simple wrong.

Any help much appreciated! I have a fallback, which will be to use an attiny to read the DHT22 and software serial to send the result.

[uhclem]

I scoped out the data pin and I see it going low for about 10 us, but not with any correlation to my code running.

[uhclem]

FWIW, my DHT22 works perfectly fine being read from an ATTINY85. I'll probably just let it talk to one of the UARTs via serial.

[adafruit_support_mike]

Honestly, that's probably the easiest solution.

Linux computers are good for a lot of things, but direct sensor IO doesn't play to their strengths. Things like I2C kernel modules/DTOs make it easier, but then you run into devices with nonstandard interfaces like the DHT22, and things get annoying again.