Somewhat irrelevant to Ada and apologies for that but if anyone’s done any work against the ADC module on a STM32f42xxx board, please feel free to chip-in. 
Thanks!
What do you want to achieve?
I’ve working code but for STM32F401 with quite complicated setup (timer to start ADC, DMA to transfer results to the memory, and interrupts to notify that half of the buffer has been filled, see