The same problem with the ADC multi-channel conversion results in STM32F0

Objective

The previous Time debugging stm32f030 ADC, encountered a strange problem in multi-channel conversion, using the official routines and library functions to convert multiple ADC channels continuously, the results of several channels are the same, the solution reference to the STM32F0 series multi-ADC single sampling data processing of the same problem , thank you for that.

Recording

The initialization and conversion methods in the official library's routine adc_basicexample are as follows

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 */
#ifdef USE_STM320518_EVAL
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 ;
#else
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 ;
#endif /* USE_STM320518_EVAL */
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 12 bits  */
ADC_InitStructure.ADC_Resolution = 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 239.5 Cycles as sampling time */ 
#ifdef USE_STM320518_EVAL
ADC_ChannelConfig(ADC1, ADC_Channel_11 , ADC_SampleTime_239_5Cycles);
#else
ADC_ChannelConfig(ADC1, ADC_Channel_10 , ADC_SampleTime_239_5Cycles);
#endif /* USE_STM320518_EVAL */

/* 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);

while (1)
{
    /* Test EOC flag */
    while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);
    
    /* Get ADC1 converted data */
    ADC1ConvertedValue =ADC_GetConversionValue(ADC1);
    
    /* Compute the voltage */
    ADC1ConvertedVoltage = (ADC1ConvertedValue *3300)/0xFFF;
    
    /* Display converted data on the LCD */
    Display();
}

Visible library functions in the switch channel is used Adc_channelconfig (ADC1, Adc_channel_11, Adc_sampletime_239_5cycles), in the library function Adc_channelconfig function source code as follows

void ADC_ChannelConfig(ADC_TypeDef* ADCx, uint32_t ADC_Channel, uint32_t ADC_SampleTime)
{
    uint32_t tmpreg = 0;

    /* Check the parameters */
    assert_param(IS_ADC_ALL_PERIPH(ADCx));
    assert_param(IS_ADC_CHANNEL(ADC_Channel));
    assert_param(IS_ADC_SAMPLE_TIME(ADC_SampleTime));

    /* Configure the ADC Channel */
    ADCx->CHSELR |= (uint32_t)ADC_Channel;

    /* Clear the Sampling time Selection bits */
    tmpreg &= ~ADC_SMPR1_SMPR;

    /* Set the ADC Sampling Time register */
    tmpreg |= (uint32_t)ADC_SampleTime;

    /* Configure the ADC Sample time register */
    ADCx->SMPR = tmpreg ;
}

where ADCX->CHSELR |= (uint32_t) Adc_channel uses "|" for register assignment, which causes the highest bit channel to still be converted when the next cycle is converted
The workaround is to write to the register after each call to Adc_channelconfig

uint16_t ADC_Get_Result(uint32_t ch)
{
    ADC_ChannelConfig(ADC1, ch, ADC_SampleTime_239_5Cycles);
    ADC1->CHSELR = ch;
    while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADRDY)){};
    ADC_StartOfConversion(ADC1);
    while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET){};
    return ADC_GetConversionValue(ADC1)&0x00000fff;
}

The same problem with the ADC multi-channel conversion results in STM32F0