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Raspberry pi problems

Posted: Thu Feb 19, 2015 1:37 pm
by bobdx_cool
Guys, I have a raspberry pi controlling my system in a remote location. The surrounding temperature is around -11 degree celsius.
I am running a multithreaded python program on the pi. There is a thread which is running continuously waiting for an RFID input to start a set of actions. From the past 2 months it was running uninterrupted . But of late I have seen the pi freezing a lot. When I check my logs, I see the following garbage characters below before the pi freezes,
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^
Is the RFID reader randomly getting these garbage values ?

What could be the reason for this ?

1.) Low temperatures ?
2.) Voltage supply problems (voltage and current drops ?) Powered USB hub drawing power from the pi instead of the supply ?
3.) Pi damaged ?
4.) RFID reader problem ( currently using serial interface for the RFID, http://www.parallax.com/product/28140)?

I recently followed the instructions on this page (http://ictoblog.nl/raspberry-pi/raspber ... tification) to autoreboot the system if the pi hangs. I have to see how this watchdog will work out.

Re: Raspberry pi hanging up

Posted: Fri Feb 20, 2015 2:55 pm
by Tarcas
I would say 1 and 2 are excellent first guesses. Fortunately they're relatively easy to test. Replace the power supply with a known good one and put the Pi and, if possible the power supply and RFID reader too, in an enclosure (probably with a nightlight bulb) to keep them warmer.

Cheap and easy. If those don't solve it, you can look into replacing the Pi or RFID reader next.