Check out this link: http://hipstercircuits.com/reading-analog-adc-values-on-beaglebone-black/
That works OK on Angstrom except it apparently is now helper14 not helper11 ?? Note the problem with current version of the driver.
On Debian, this didn’t work for me but I found the raw readings available at: /sys/devices/ocp.2/44e0d000.tscadc/tiadc/iio:device0 which is also the same for Angstom.
As the calls require root did you wrap the echo command, such that they can work… Sudo sh -c "echo … "