Strange problem reading analog-in, segmentation fault

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1

I am new to the Beaglebone, and was moving along at a pretty good click until this strange problem popped-up. I spent all weekend trying to figure it out before posting here.

I am trying to read analog input using multiple sensors from a beaglebone with Angstrom 3.2.5+ and I have a problem that I think might be a hardware issue.

Using this Python script and Alexander Hiam's PyBBIO I have been able to test a photoresistor with success (the value responds to more and less incidental light):
https://gist.github.com/2698550

But...

1. Any other analog-in (AINx(2-7)) I read with the script above always shows the same value of the photo resistor I have plugged-into AIN1

And, possibly related...

2. I am unable to read any of the AINx(1-7) using cat with an error:

# cat /sys/bus/platform/devices/tsc/ain1
Segmentation fault

Any ideas? I am really stuck. Thanks in advance.

Owen

PS:

More info...

My circuit consists of a 10k resistor and a photoresistor. My pin connections are:
  • Header P9 Pin 32 (VDD_ADC(1.8V)) to one end of photocell
  • Header P9 Pin 34 (GNDA_ADC) to the other end of the resistor
  • Header P9 Pin 39 (AIN0) to the other side of the photocell along with one end of pull down resistor
Here is an image which matches my own circuit:
http://2.bp.blogspot.com/-6XuT3btrNsk/T5DGlIt0oeI/AAAAAAAAAAQ/xXac6xQkLUg/s1600/Smalltalk+on+the+BeagleBone.png

The results from all of the AINx(1-7)'s and then some...

# cat /sys/bus/platform/devices/tsc/ain0
cat: /sys/bus/platform/devices/tsc/ain0: No such file or directory
# cat /sys/bus/platform/devices/tsc/ain1
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain2
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain3
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain4
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain5
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain6
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain7
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain8
Segmentation fault
# cat /sys/bus/platform/devices/tsc/ain9
cat: /sys/bus/platform/devices/tsc/ain9: No such file or directory

2

OK, the answer is that there are two separate problems, both of which are caused by using the (otherwise great) PyBBIO library.

After thinking about this a bit I decided to try to repeat the results with a script without using PyBBIO. I wrote a new Python file to test and print the reading from each analog-in pin on the BeagleBone using the Python os module. The file uses os.system('cat ...') to print the values, and includes a short delay between each.

I've posted the whole answer with test results here.
http://stackoverflow.com/questions/10611294/reading-analog-in-on-beaglebone-avoiding-segmentation-fault-error

Owen