implemented DMA-based averager. Avg res is dumped to USB_VCP. But it is not compiles

Core/Src/main.c

@@ -59,6 +59,14 @@ static void MX_ADC1_Init(void);
 
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
+struct ADC_proc{
+  uint8_t status; // 0 - stopped, 1 - started-filling, 2 - filled
+  uint32_t sum;
+  uint32_t avg;
+  uint32_t N;
+} adc_process;
+
+
 #define ADC_BUFF_SIZE 100
 uint16_t ADC1_buff_circular[ADC_BUFF_SIZE];
 /* USER CODE END 0 */
@@ -98,6 +106,11 @@ int main(void)
   /* USER CODE BEGIN 2 */
   HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_SET);
   HAL_ADC_Start_DMA(&hadc1, (uint32_t*)ADC1_buff_circular, ADC_BUFF_SIZE);
+  adc_process.status = 0; // ADC started
+  adc_process.N = 0;
+  adc_process.sum = 0;
+  adc_process.avg = 0;
+
   /* USER CODE END 2 */
 
   /* Infinite loop */
@@ -106,7 +119,31 @@ int main(void)
   {
     HAL_GPIO_TogglePin(LED_RED_GPIO_Port, LED_RED_Pin);
     HAL_Delay(100);
+
+    if (adc_process.status == 2) {
+      adc_process.avg = adc_process.sum / adc_process.N;
+      adc_process.status = 1; // reset for next accumulation
+      adc_process.sum = 0;
+      adc_process.N = 0;
+      char digits[10] = {0};
+      digits[0] = (adc_process.avg / 1000000000) % 10 + '0';
+      digits[1] = (adc_process.avg / 100000000) % 10 +  '0';
+      digits[2] = (adc_process.avg / 10000000) % 10 + '0';
+      digits[3] = (adc_process.avg / 1000000) % 10 + '0'; 
+      digits[4] = (adc_process.avg / 100000) % 10 + '0';
+      digits[5] = (adc_process.avg / 10000) % 10 + '0';
+      digits[6] = (adc_process.avg / 1000) % 10 + '0';
+      digits[7] = (adc_process.avg / 100) % 10 + '0';
+      digits[8] = (adc_process.avg / 10) % 10 + '0';
+      digits[9] = (adc_process.avg / 1) % 10 + '0';
+
+      CDC_Transmit_FS((uint8_t *)"ADC Average calculated: ", 24);
+      CDC_Transmit_FS((uint8_t *)digits, 10);
+      CDC_Transmit_FS((uint8_t *)"\r\n", 2);
+
+    }
     CDC_Transmit_FS((uint8_t *)"Hello from STM32!\r\n", 19);
+    
     /* USER CODE END WHILE */
 
     /* USER CODE BEGIN 3 */

Core/Src/stm32f4xx_it.c

@@ -58,7 +58,7 @@
 extern PCD_HandleTypeDef hpcd_USB_OTG_FS;
 extern DMA_HandleTypeDef hdma_adc1;
 /* USER CODE BEGIN EV */
-
+extern struct ADC_proc adc_process;
 /* USER CODE END EV */
 
 /******************************************************************************/
@@ -232,6 +232,11 @@ void OTG_FS_IRQHandler(void)
 void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
 {
   HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_SET);
+  for (uint32_t i = ADC_BUFF_SIZE/2; i < ADC_BUFF_SIZE; i++) {
+    adc_process.sum += ADC1_buff_circular[i];
+  }
+  adc_process.N += ADC_BUFF_SIZE - ADC_BUFF_SIZE/2;
+  adc_process.status = 2; // buffer filled
     // This function is called when the first half of the ADC buffer is filled
     // You can process the first half of ADC1_buff_circular here
 }
@@ -243,6 +248,11 @@ void HAL_ADC_ConvHalfCpltCallback(ADC_HandleTypeDef* hadc)
   //HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_RESET);
 
   HAL_GPIO_TogglePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin);
+  for (uint32_t i = 0; i < ADC_BUFF_SIZE/2; i++) {
+    adc_process.sum += ADC1_buff_circular[i]; 
+  }
+  adc_process.N += ADC_BUFF_SIZE/2;
+  
     // This function is called when the first half of the ADC buffer is filled
     // You can process the first half of ADC1_buff_circular here
 }