How to Read and Show ADC value of STM32F4 using HAL Library

Question

I have a code generated by STMCubeMX where I use the portal PA0 like ADC Input. I'm trying to read this input using HAL Library of STM in C and transmit the value to USB port using CDC. See the main, where i try to get the data and show this:

#include "main.h"
#include "usb_device.h"
#include "usbd_cdc_if.h"

ADC_HandleTypeDef hadc1;
void SystemClock_Config(void);
static void MX_ADC1_Init(void);

int main(void)
{
    uint8_t buffer[8];

    HAL_Init();
    SystemClock_Config();
    MX_USB_DEVICE_Init();
    MX_ADC1_Init();

    HAL_ADC_Start(&hadc1);

    while (1)
    {
        HAL_GPIO_TogglePin(GPIOC,GPIO_PIN_14);
        HAL_ADC_PollForConversion(&hadc1, 1000);
        sprintf((char*)buffer,"%d\n",(int)HAL_ADC_GetValue(&hadc1));
        //HAL_Delay(500);
        CDC_Transmit_FS(buffer,8);
    }
}

Debugging the code I saw that function "HAL_ADC_PollForConversion(&hadc1, 1000)" never returns "HAL_OK". In the terminal, a single value appears.

UPDATE

Well, for the code works I have to put the "Start" of ADC inside of infinit loop and a call of "Stop" on the final of loop. Ps: The Adc is running on continuous conversion mode.

int main(void)
{
    uint8_t buffer[8];

    HAL_Init();
    SystemClock_Config();
    MX_USB_DEVICE_Init();
    MX_ADC1_Init();

    while (1)
    {
        HAL_ADC_Start(&hadc1);
        HAL_GPIO_TogglePin(GPIOC,GPIO_PIN_14);
        HAL_ADC_PollForConversion(&hadc1, 1000);
        sprintf((char*)buffer,"%d\n",(int)HAL_ADC_GetValue(&hadc1));
        //HAL_Delay(500);
        CDC_Transmit_FS(buffer,8);
        HAL_ADC_Stop(&hadc1);
}

}

Answer 1

As an addition to the answer in the comments:

The call to HAL_ADC_PollForConversion(&hadc1, 1000); explicitly stops the conversion, even if continuous conversion is activated.

If you you want/must wait for each conversion to get finished, you must restart the ADC with HAL_ADC_Start(&hadc1); after waiting (and reading) for the result.