Swm32 series tutorial 5-adc application

1.ADC Function is introduced

SWM32SRET6 MCU built-in 2 individual 12 position SAR type ADC, Most support 8 passageway ,1MSPS Conversion rate . Support software trigger 、 Timer triggered . The design of the single chip microcomputer ADC The block diagram of module structure is as follows ,

The ADC Compared with other MCU internal ADC Come on , There are two characteristics , One is hardware averager , One is 8 Level depth FIFO. Hardware averagers can reduce CPU Average workload of software ,8 Level depth FIFO It can also reduce the frequency of interrupts （ If enabled, interrupt ）, Both improve the efficiency of the program . The only regret is that I didn't see DMA Part content , It should not support DMA Read .      

2. Serial port application

Look at the program directly ：

void ADCInit(void)
{
  ADC_InitStructure ADC_initStruct;


  PORT_Init(PORTC, PIN6,  PORTC_PIN6_ADC1_IN1,  0);  //PC6  => ADC1.CH1


  ADC_initStruct.clk_src = ADC_CLKSRC_VCO_DIV64;  // Be careful ：ADC1 Only use VCO The clock , Out of commission ADC_CLKSRC_HRC
  ADC_initStruct.clk_div = 25;
  ADC_initStruct.pga_ref = PGA_REF_INTERNAL;
  ADC_initStruct.channels = ADC_CH1;
  ADC_initStruct.samplAvg = ADC_AVG_SAMPLE16;  //16 Secondary hardware average 
  ADC_initStruct.trig_src = ADC_TRIGSRC_SW;    // Software triggers 
  ADC_initStruct.Continue = 1;                // Continuous mode 
  ADC_initStruct.EOC_IEn = 0;  
  ADC_initStruct.OVF_IEn = 0;
  ADC_initStruct.HFULL_IEn = ADC_CH1;          // Can make FIFO Half full interrupt 
  ADC_initStruct.FULL_IEn = 0;
  ADC_Init(ADC1, &ADC_initStruct);            // To configure ADC


  ADC_Open(ADC1);                              // Can make ADC
  ADC_Start(ADC1);
}

Initialization required first IO The mouth is ADC The input mode .ADC Of IO It can only be fixed , Unlike UART And other digital interfaces can be flexibly configured .

The second is ADC Configuration of functions . First select the clock source and channel , It's enabled here ADC1 Of CH1, If multiple channel scanning is required , Then several channel numbers can be matched ：

ADC_initStruct.channels = ADC_CH1| ADC_CH2| ADC_CH3;

Open the 16 Secondary hardware average , That is, start a conversion , Hardware automatic sampling 16 Times and output the average value .

Here the continuous conversion mode is enabled . Open the FIFO Half full interrupt .ADC There are multiple interrupt sources ：

EOC_IEn-- End of conversion interrupt

OVF_IEn--FIFO Overflow interrupt

HFULL_IEn—FIFO Half full interrupt

FULL_IEn—FIFO Full interrupt

The end of conversion interrupt is every ADC Interrupt once after the conversion . Because of FIFO The existence of , It's enabled here FIFO Half full interrupt , such ADC After sampling, the data will be stored automatically FIFO in , When FIFO When half full, interrupt reading all data at once . This can reduce the frequency of program interruption .

In interrupt function , You need to clear the interrupt flag , Read FIFO Data in , If it is a single conversion mode , It needs to be triggered again ADC transformation . The procedure is as follows ：

uint16_t adc_buf[100];
uint16_t adc_cnt = 0;
void ADC1_Handler(void)
{  
  ADC1->IF = (1 << ADC_IF_CH1HFULL_Pos);//


  while((ADC1->CH[1].STAT & ADC_STAT_EMPTY_Msk) == 0)// read out FIFO All data in 
  {
    adc_buf[adc_cnt] = ADC_Read(ADC1, ADC_CH1);
    adc_cnt++;
    if(adc_cnt == 100)
      adc_cnt = 0;
  }


  //ADC_Start(ADC1);
}

Recommended reading ：

several RS485 Introduction to the scheme of isolated communication

SWM32 Series of tutorials 4- Port mapping and serial port application

Internal oscillator 、 Passive crystal oscillator 、 What is the difference between active crystal oscillators ？

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