BBB ADC (potentiometer demo) slow in updating values to console

Hi everyone,

This is my first post in this forum.

I connected BBB (running Angstrom) and ran the code in this link from browser. Instead of a pot, there’s a LDR-resistor network.

Vdd_ADC 1.8V goes to a 47k resistor.
From resistor, an LDR (9k ohms in light and around 115k in dark). Other end of LDR connected to GNDA_ADC
P9.40 (AIN1) of BBB connected between the resistor and LDR.

On pressing the Run button, the console shows value “x.value = 0.12777777777777777” when LDR is exposed to light.
I removed the source of light (covered the LDR with finger) and pressed Run button. The value doesn’t change. It’s “x.value = 0.12611111111111112”
On pressing the Run button again, the value gets updated: “x.value = 0.40944444444444444”

The value must get updated in the second step itself, right? Why doesn’t it happen so?


Found out from Google that there was a bug in ADC driver.
Flashed eMMC with 2013.09.04 image and problem solved!

By the way, can someone help me with the configuration of interrupts on completion of ADC? Is there any article on interrupts in Beaglebone Black in general?