The STM32L476-DISCO platform HAL contains some test programs which allow various aspects of the board to be tested.
The adc1 program tests the ADC driver for the STM32. In order to run this test a potentiometer needs to be connected to the board; outer pins to 3V3 and GND (P1:1 and P1:2 are convienient), and the center pin to P1:10, which is attached to PA0. This test primarily tests that the external input functions correctly. However, in addition it also reports the values of the Vrefint, Vbat and Vts inputs that are sourced on-chip. The option CYGBLD_HAL_CORTEXM_STM32L476_DISCO_TESTS_ADC must be enabled to run this test since it needs human interaction.