HIH4000 conversion doesn't consider supply voltage
As it's implemented now in e.g. temp_hum_monitor, the ADC reference voltage is set to 1V and it's assumed the HIH4000 supply voltage is the same, so it works out.
As it's implemented now in e.g. temp_hum_monitor, the ADC reference voltage is set to 1V and it's assumed the HIH4000 supply voltage is the same, so it works out.