[HAL][ADC] Change ADC calibration procedure

Author: RJMSTM

Src/stm32c0xx_hal_adc_ex.c

@@ -166,11 +166,13 @@ HAL_StatusTypeDef HAL_ADCEx_Calibration_Start(ADC_HandleTypeDef *hadc)
           return HAL_ERROR;
         }
       }
-
-      calibration_factor_accumulated += LL_ADC_GetCalibrationFactor(hadc->Instance);
+      /* Read the calibration factor and increment by one */
+      calibration_factor_accumulated += (LL_ADC_GetCalibrationFactor(hadc->Instance) + 1UL);
     }
-    /* Compute average */
+    /* Compute average (rounded up to the nearest integer) */
+    calibration_factor_accumulated += (calibration_index / 2UL);
     calibration_factor_accumulated /= calibration_index;
+
     /* Apply calibration factor (requires ADC enable and disable process) */
     LL_ADC_Enable(hadc->Instance);