ADC0 setup and in_voltage_raw reading
Running Ubuntu 14.04 + Ubilinux kernel. ADC is enabled in BIOS.
I have 24V connected to a voltage divider (R1=68k, R2=10k) and the output connected to ADC0/GPIO4/PIN7.
Via sysfs, I export gpio4, set direction to in, and connect the output of the voltage divider.
When I read in_voltage_raw (via sysfs /sys/bus/iio...), I get "7" or "8" no matter what, unless I ground it, which I get "0".
in_voltage_scale is 12.890625.
The voltage at the ADC0 pin is around 3.2 so I am expecting (3.2*1000) / 12.89, or 3.2/255, or something, but this thing just reads the same value regardless if its 1.2V, 2.4V at the pin or 3.2V.
How do you correctly setup this ADC0 pin? Do I need to drop the resistor values to 6.8k/1k? I don't know what the desired current rating for this pin is, and I cannot find any setup information to know if I am correctly exporting, writing direction, etc or if there are more steps I need to take to configure ADC0.
Answers
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Hi @drm87
Ubuntu 14.04 may be too old, which may cause the driver to not work properly.
Please install a new version of Ubuntu before testing.Best Regards,
Harry Chiu
