STM32l1xx Internal ADC Channels

Hi,

I have been working with the STM32L151RC uc and would like to read two of it’s internal ADC channels. The problem is RIOT present implementation por the ADC only takes into account external ADC lines, witch means it require a GPIO assignment. What would be the best way of implementing this? a new function in the adc lib that doesn’t need a GPIO assignment or implement this a a CPU function since these internal ADC channels are used to get internal voltage references and such. Best regards,

Francisco Molina