RAK811 RUI, battery powered, measure self battery

Hi,
Any advance on this? posted a few months ago auto-closed without a response.

I want to read the battery of a node that uses RAK811 module and is programmed using RUI, based on RAK7204 code example.

rui_adc_get() function uses VCC (battery voltage) as vref for the ADC, so the resistor divider method will not work. (Tested!. Will show the same value regardless battery voltage)

In rui.h i found a header for rui_device_get_battery_level() function, which i suppose was designed for that purpose using the internal 1.2v reference, however when this function is included in the code, the online compiler throws errors “unknown function”.

So,someone can point me a working and tested example of battery self measurement with RAK811 module and RUI, without active external components.

Thanks in advance!