Problem with scanf in STM32F4, it is scanning only the first char even I am requesting to scan an int or float. Details in description

here is the code I am using to scan

int ScanConfig(__const char * format, va_list args) {
 unsigned i=0;
 char ch = 0;
 char buffer[256];
 int ret = 0;
 while((i<sizeof(buffer))&&(ch!='\n')&&(ch!='\r')){
 HAL_StatusTypeDef status = HAL_TIMEOUT;
 while (status == HAL_TIMEOUT) {
 status = HAL_UART_Receive(&UartHandle1, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
 if (status == HAL_TIMEOUT) {
 /*HAL_UART_DeInit(&rxHandle);
 HAL_UART_Init(&rxHandle);*/
 }
 else
 break;
 }
 
 buffer[i]=ch;
 i++;
 ret = vsscanf(buffer, format, args);
 if (ret > 0)
 break;
 }
 buffer[i]=0;
 return ret;
}
int Scan(__const char * format, ...) {
 va_list args;
 va_start(args, format);
 int size = ScanConfig(format, args);
 va_end(args);
 return size;
}

I am calling the function like this:

Scan("%f",&InVar);

The problem that if I try to enter 4.5 for example, I can't and it saves only 4.