On Sat, 29 Jul 2017 14:20:01 +0100, Adrian wrote:

> PI 2 running Raspbrian, patched up to date a month ago.
>
> I've been running a Pi2 with a DHT22 temperature/humidty sensor attached
> since early June, and initially all was well.  It seems that the Edimax
> WiFi dongle stopped functioning (symptom was no network connectivity),
> on attempting to reboot, the whole thing stopped working, that looks as
> though it was the power supply that died.
>
> I've put another power supply on, and apart from the network connection
> still not working, all seemed well, until I looked at what the DHT22 was
> doing, running the Adafruit_Python_DHT/examples/AdafruitDHT.py script I
> get :
>
> Traceback (most recent call last):
>    File "/home/pi/Adafruit_Python_DHT/examples/AdafruitDHT.py", line 41,
> in 
>      humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
>    File "build/bdist.linux-armv7l/egg/Adafruit_DHT/common.py", line 94,
> in read_retry
>    File "build/bdist.linux-armv7l/egg/Adafruit_DHT/common.py", line 81,
> in read
>    File "build/bdist.linux-armv7l/egg/Adafruit_DHT/Raspberry_Pi_2.py",
> line 34, in read RuntimeError: Error accessing GPIO.
>
>
> Rummaging around online, I've seen various references to this, but they
> all seem to be for new installs, not a problem that has developed.
>
> One thought that occurred to me was that the new power supply (borrowed
> from my phone) might not have enough power output for anything more than
> the basic board.
>
> Any suggestions on where to look next ?
>
> Adrian

It is possible that the SD card was corrupted as the power supply died.
You might try reloading raspian (and, of course, you can always back up
the current card on a full sized computer).

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