STM32F051 -> ADC1 -> sometimes no value returned....

Dear community,

I investigated the ADC_BasicExample given in the STM32F0xx_StdPeriph_Lib_V1.5.0 Database. I did a few changes since I want to analyze the converted value with the PC via UART. However I noticed if the EOC flag was cleared not necessarily the ADC returned a value. Is the interrupt better suited than the polling method given in the basic example ?

Here is some code for review:

//some functions to trigger the praser located on a remote pc 
int SendChar(char ch) //copied from USART example
{
// Place your implementation of fputc here 
// e.g. write a character to the USART 
USART_SendData(USART1, (uint8_t) ch);
// Loop until transmit data register is empty 
while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET); 
return ch;
}
void print(char * string) {
char primer[] = ''print'';
int count;
//send primer
for(count = 0; count < 5; count++) SendChar(primer[count]); 
//now sen the string to print 
while(!(*string == '\0')) {
SendChar(*string); 
string++; 
}
SendChar(10); //now send the end of the string
}
void Send_value(int * value) {
char primer[] = ''value'';
int count;
//send primer
for(count = 0; count < 5; count++) SendChar(primer[count]);
//now send the char to the pc via uart
SendChar(*value);
}
//ADC1 Init
void ADC_Config(void) //copied from ADC_BasicExample
{
ADC_InitTypeDef ADC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
// GPIOC Periph clock enable 
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC, ENABLE);
// ADC1 Periph clock enable 
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
// Configure ADC Channel11 as analog input 
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 ;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOC, &GPIO_InitStructure);
// ADCs DeInit 
ADC_DeInit(ADC1);
// Initialize ADC structure 
ADC_StructInit(&ADC_InitStructure);
// Configure the ADC1 in continuous mode with a resolution equal to 8 // 12 bits 
ADC_InitStructure.ADC_Resolution = ADC_Resolution_8b;// ADC_Resolution_12b; //ADC_Resolution_8b;//ADC_Resolution_12b;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE; 
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Upward;
ADC_Init(ADC1, &ADC_InitStructure); 
// Convert the ADC1 Channel 11 with 5 Cycles as sampling time 
ADC_ChannelConfig(ADC1, ADC_Channel_11 , ADC_SampleTime_239_5Cycles);
// ADC_ChannelConfig(ADC1, ADC_Channel_10 , ADC_SampleTime_239_5Cycles);
// ADC Calibration 
ADC_GetCalibrationFactor(ADC1);
// Enable the ADC peripheral 
ADC_Cmd(ADC1, ENABLE); 
// Wait the ADRDY flag 
while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADRDY)); 
// ADC1 regular Software Start Conv 
ADC_StartOfConversion(ADC1);
}
void InitPeriphery() {
COM_USART1_Init();
ADC_Config();
}
int main(void) {
int received;
InitPeriphery();
while(1) { 
while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);
received = ADC_GetConversionValue(ADC1);
if(received) Send_value(&received ); // somtimes ADC_GetConversionValue was passed however access to ''received'' was somehow impossible 
print(''+ \0''); //waste some time to check the praser is working
print('' + \0'');
print('' + \0'');
print('' + \0'');
print('' + \0'');
print('' + \0'');
print('' + \0'');
};
}