AVR series ADC conversion

Let's sort out the ADC conversion function of AVR. The digital-to-analog converter in AVR is a 10-bit successive approximation ADC. It provides 8 single-ended input channels. The single-ended voltage is based on 0V. It also has 7 differential input channels. These seven differential channels share a common negative terminal (ADC). The input voltage range is 0~VCC. Its conversion time is 65~260uS. The phenomenon of the following program is that the serial port sends a command to start the ADC and sends the result to the PC through the serial port. Any character is turned on

#include

#include  < macros.h >

#define uchar unsigned char

uchar UcAdcData; //ADC conversion result  

uchar AdcConCom = 0; //ADC conversion completion flag  

uchar admuxx = 0x67; //External reference source data storage left alignment

//AD conversion initialization

void AdcInit(void)
{
     ADCSR = 0x00; //ADC invalid
     ADMUX = admuxx; //Select ADC channel 7
     /*--REFS1---REFS0---ADLAR---0--------------Reference power supply selection------Alignment--------*/
     /*--0000-- 0001-- 0010-- 0011-- 0100-- 0101-- 0110-- 0111-- 1110--- --1111---*/
     /*--Channel 0--Channel 1--Channel 2--Channel 3--Channel 4--Channel 5--Channel 6-Channel 7--1.23V(VBG)-0V(GND)*/
     ACSR = 0x80; //Analog comparator control and status register ACSR
                                                             //ACD is set to 1 to disable the analog comparator
    /*--ACD--ACBG--ACO--ACI---ACIE---ACIC---ACIS1---ACIS0------------------------*/
   /*-Analog comparator disable--Analog comparator energy gap reference source--Analog comparator output--Analog comparator interrupt flag*/
   /*-Analog comparator interrupt enable--Analog comparator input capture enable--Analog comparator interrupt mode selection-------- */
    ADCSR = 0x8B; //Analog comparator control and status register
    /*-----------ADEN---ADSC---ADFR---ADIF---ADIE---ADPS2---ADPS1---ADPS0--------*/
    //Enable analog-to-digital conversion ADC starts conversion ADC continuous conversion ADC interrupt enable 128 division
}

//AD conversion interrupt processing function

#pragma interrupt_handler adc_isr : 15
void adc_isr ( void )                 

{
     UcAdcData = ADCH; //Read ADC conversion result
     AdcConCom = 1; //Set ADC conversion completion flag
}

//Serial port initialization

void Uart0Init(void)
{
     UCSRB = 0x00; //Close the serial port
     UCSRA = 0x02; //Speed ​​mode M16 Chinese P151
     UCSRC = BIT(URSEL) | 0x06; //Write UCSRC register, set 8 bits
     UBRR = 0x000c; //Set the serial port baud rate to 9600
     UCSRB = 0x98; //Open the serial port
}

//Serial port interrupt processing function

#pragma interrupt_handler UartRecvData:12
void UartRecvData(void) //Serial port interrupt processing function, that is, PC sends a start signal to AVR
{
      uchar temp;
      temp = UDR;
      ADMUX |= 0x07;
      ADCSR |= 0x40; //Start an ADC conversion
}

//Serial port sends data

void UartTransmitData(void)
{
    while(!(UCSRA&0x20)); //Judge whether the data register is empty
    UDR = UcAdcData;
}

// Initialize various information

void InitDevices(void)
{
    CLI ( ); //Disable all interrupts
    Uart0Init ( ) ;
    AdcInit ( ) ;

    MCUCR = 0x00;
    SEI ( ) ; // Enable all interrupts
}

//Main function

void main ( void )

{

       InitDevices ( ) ; //Serial port initialization
       while ( 1 )
      {
           if ( AdcConCom ) //AD completion flag starts processing data
           {
               AdcConCom = 0; //Clear ADC conversion completion flag
               UartTransmitData ( ) ; //Send conversion results
           }
      }

}