HAL_ADC_Start_DMA example, always get value 0
hi guys, i'm stm freshman, I am trying to read the adc value by using the adc example of stm32f4, I added bold code to get uhADCxConvertedValue value, but uhADCxConvertedValue value always get 0 Whether I connect adc pin to grounded or vcc.the led4 ...