title: ADC single conversion on STM32
body: <p>I'm studying ADC programming on STM32 F103x and starting with the simplest case - single conversion. 
  The internal temperature sensor (connected to ADC1) value is measured and sending it to COM port by using USART. A target seems clear but when I try to download source code to flash, it doesn't send any data to COM port. USART function works well, I guess the problems come from ADC configuration part because I'm being hung in loop of waiting complete conversion:</p>
  
  <pre><code>while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET); //Wail for conversion complete
  </code></pre>
  
  <p>Here is my source code so far.</p>
  
  <pre><code>/* Includes ------------------------------------------------------------*/
  #include "stm32f10x.h"
  #include &lt;stdio.h&gt;
  
      uint16_t AD_value;
      const uint16_t V25 = 1750; //when V25=1.41V
      const uint16_t Avg_Slope = 5; //when avg_slc
      uint16_t TemperatureC;
  
  //Define output device
  PUTCHAR_PROTOTYPE
  {
      USART_SendData(USART1, (uint8_t) ch);
      while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET)
      {}
      return ch;
  }
  
  void Usart1Init(void)
  {
      GPIO_InitTypeDef GPIO_InitStructure;
      USART_InitTypeDef USART_InitStructure;
  
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
  
      /* COnfig PA9 for USART Tx as alternate function push-pull */
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_Init(GPIOA, &amp;GPIO_InitStructure);
  
      /* COnfig PA10 for USART Rx as input floating */
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
      GPIO_Init(GPIOA, &amp;GPIO_InitStructure);
  
      /* USARTx configured as follow:
          - BaudRate = 9600 baud  
          - Word Length = 8 Bits
          - One Stop Bit
          - No parity
          - Hardware flow control disabled (RTS and CTS signals)
          - Receive and transmit enabled
      */  
      USART_InitStructure.USART_BaudRate = 9600;
      USART_InitStructure.USART_WordLength = USART_WordLength_8b;
      USART_InitStructure.USART_StopBits = USART_StopBits_1;
      USART_InitStructure.USART_Parity = USART_Parity_No;
      USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
      USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
  
      /* USART configuration */
      USART_Init(USART1, &amp;USART_InitStructure);
      USART_Cmd(USART1, ENABLE);  
  
  }
  
  int main(void)
  {
  
      ADC_InitTypeDef ADC_InitStructure;
      Usart1Init();
  
      RCC_ADCCLKConfig(RCC_PCLK2_Div6); //ADCCLK = PCLK22/6 = 72/6=12MHz
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE); //Enable ADC1 Clock
  
      /* ADC1 configuration */
      ADC_DeInit(ADC1); //Power-on default
      ADC_InitStructure.ADC_Mode = ADC_Mode_Independent; //Independent conversion mode (single)
      ADC_InitStructure.ADC_ScanConvMode = DISABLE; //Convert single channel only
      ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; //Convert 1 time
      ADC_InitStructure.ADC_ExternalTrigConv = DISABLE; //No external triggering
      ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; //Right 12-bit data alignment
      ADC_InitStructure.ADC_NbrOfChannel = 1; //single channel conversion
      ADC_Init(ADC1, &amp;ADC_InitStructure);
      ADC_TempSensorVrefintCmd(ENABLE); //wake up temperature sensor
      ADC_Cmd(ADC1, ENABLE); //Enable ADC1
      ADC_ResetCalibration(ADC1); //Enable ADC1 reset calibration register
      while(ADC_GetResetCalibrationStatus(ADC1)); //check the end of ADC1 reset calibration register  
      ADC_StartCalibration(ADC1); //Start ADC1 calibration
      while(ADC_GetCalibrationStatus(ADC1)); //Check the end of ADC1 calibration
      ADC_RegularChannelConfig(ADC1, ADC_Channel_16, 1, ADC_SampleTime_1Cycles5); //Select 1.5 cycles conversion for channel 16
      ADC_SoftwareStartConvCmd(ADC1, ENABLE); //Start ADC1 software conversion
      while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET); //Wail for conversion complete
      AD_value = ADC_GetConversionValue(ADC1); //Read ADC value
      ADC_ClearFlag(ADC1, ADC_FLAG_EOC); //Clear EOC flag
  
      printf("\r\n ADC value: %d \r\n", AD_value);
      TemperatureC = (uint16_t)((V25-AD_value)/Avg_Slope+25);
      printf("Temperature: %d%cC\r\n", TemperatureC, 176);
      while (1)
      {}  
  }
  </code></pre>
  
  <p>Any ideas are appreciated!</p>