ARM9(S3C2440) ADC

Analog signal/digital signal

(1) An analog signal is a physical quantity that is continuous in time and value, and has an infinite number of values. Most physical quantities perceived from nature are analog in nature, such as speed, pressure, temperature, sound, etc.

(2) Digital signals are discrete in both time and value, and the values ​​of discrete signals are only true or false, yes or no, so they can be represented by 0 and 1 in binary.

ADC driving process

ADC main driver

main.c

#define ADC_FREQ 2500000

void Main(void)

{

    /*Clock initialization*/

    Set_Clk();

    /*ADC initialization*/

    adc_init();

    while(1)

    {

     /*Read the conversion value*/

        adc_value=ReadAdc(0);

 delay(1000);

    }

}

void adc_init(void)

{undefined

 //Select the input channel, AIN0, corresponding to the W1 adjustable resistor on the development board

 int channel=0;

 /*Set the divided clock*/

 preScaler = ADC_FREQ;

 preScaler = 50000000/ADC_FREQ - 1; //PCLK=50M

 /*AD conversion frequency setting, maximum frequency is 2.5MHz*/

 rADCCON = (1<<14)|(preScaler<<6)|(channel<<3); //setup channel

 delay(1000);  

}

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

int ReadAdc(int channel)

{undefined

   /*Start AD conversion*/

   rADCCON |= 0x01; //start ADC

   while(rADCCON & 0x1); //check if Enable_start is low

   /* Check if the conversion is finished */

   while(!(rADCCON & 0x8000)); //check if EC(End of Conversion) flag is high

   return ( (int)rADCDAT0 & 0x3ff );

}