access to BBAI analog inputs

I have successfully read the values from AIN4-6 using the file system as described here:
https://www.element14.com/community/community/project14/visionthing/blog/2019/11/16/beagleboard-ai-brick-recovery-procedure#jive_content_id_ANALOG_INPUT

However, I have not yet found a way to read AIN0-3. Attempting to access the in_voltagex_raw files for these pins results in a connection timeout. How can I utilize these ADC pins?

Thanks,
Diane