STM8L ADC

STM8L ADC

/***********************************************************************************

*Name: Hal_Comm_GetBatADC

*Function: Get battery power information

*Entry parameters: None

*Export parameter: AD value of power

*illustrate: 

***********************************************************************************/

unsigned int Hal_Comm_GetBatADC(void)

{

unsigned int Result = 0, value_adc = 0;

unsigned char index = 0;

  GPIO_Init(VOL_ADC_PORT,VOL_ADC_PIN,GPIO_Mode_In_FL_No_IT);//VOL_ADC

  ADC1->CR1 |= 0x01; // Enable AD

  ADC1->CR3 &= ~0x1F; // Select sampling time 384 cycles Channel clear 

  ADC1->CR3 |= 0x00; // channel 0 is selected 

  ADC1->SQR[0] = ADC1->SQR[1] = ADC1->SQR[2] = ADC1->SQR[3] = 0x00;

  ADC1->SQR[3] = 0x01; // Select channel 0 to scan  

  ADC1->SR &= 0x00; // conversion not complete 

  ADC1->SR = 0; // conversion flag cleared

  ADC1->CR1 |= 0x03; // Enable AD and start conversion 

  while(!(ADC1->SR & 0x01)); //waitloop bit0: 1 complete 0 not complete 

  for(index = 0; index < 10; index++)

  {

    ADC1->SR = 0; // conversion flag cleared 

    ADC1->CR1 |= 0x03; // Enable AD and start conversion

    while(!(ADC1->SR & 0x01));//waitloop conversion complete 

    Result = ADC1->DRH; //Calculate a total of 16 bits, but ADC is 12 bits long

    Result <<= 8; //ADC1->DRH is the high 8 bits,

    Result += ADC1->DRL; //ADC1->DRL is the lower 8 bits

    value_adc += Result;

if(index != 0)value_adc = value_adc/2; //Get multiple data and calculate the average value  

    index++;

  }

  ADC1->CR1 &= 0xFE; // turn off AD 

  ADC1->CR3 &= ~0x1F; //Select channel 

  ADC1->CR3 |= 0x11; 

return value_adc;

}

When designing schematics, we usually set the ADC input voltage range to 0~3.3v. If the ADC is set to 12 bits, then the 12-bit full scale corresponds to 3.3V, and the digital value corresponding to the 12-bit full scale is 2^12. The value 0 corresponds to 0V. If the converted ADC value is X, and the analog voltage corresponding to X is Y, then there will be such an equation: 2^12/3.3=X/Y, => Y=(3.3*X)/2^12

In our smart lock project, the full-scale Vref is 3.31V, total voltage (M6V)/test voltage (VOL_ADC) = 3

4096/3.31 = value_adc/Va

Va = value_adc * 3.31 / 4096

Total voltage = Va * 3

That is, vin in the program = value_adc * 3.31 * 3 / 4096