Cortex_A9----ADC

ADC实验
一、看原理图，找到电位器接AD的通道3
二、看芯片手册
   ADCCON
   RES  [16]： 1 = 12bit A/D conversion
   ECFLG[15]： 0 = A/D conversion in process
   1 = End of A/D conversion
   PRSCEN  [14]： 1 = Enable
   PRSCVL  [13:6]：0xff
   STANDBY  [2]: 0 = Normal operation mode
   READ_START [1]: A/D conversion start by read
   0 = Disables start by read operation
   1 = Enables start by read operation  
   ENABLE_ST ART [0] : 0 = No operation
   1 = A/D conversion starts and this bit is automatically clearedafter the start-up.

    ADCDAT
    DATA [11:0]: ADC conversion data value Data value: 0x0 ~ 0xFFF
 
    ADCMUX
    SEL_MUX  [3:0]: 0011 = AIN 3

#include "exynos_4412.h"

void adc_init()
{
        printf("\n************ ADC Converter Value ************\n");
        /***通道选择:3****/
        ADCMUX = ADCMUX & (~(0xF << 0)) | (0x3 << 0);
        /**
        * 寄存器配置方式1
        * ADCCON = (0x1 << 16) | (0x1 << 14) | (0xff << 6);
        */
        /***12位转换精度***/
        ADCCON = ADCCON & (~(0x1 << 16)) | (0x1 << 16);
        /***使能预分频***/
        ADCCON = ADCCON & (~(0x1 << 14)) | (0x1 << 14);
        /*** AD是时钟频率100M/(19+1) = 5M ***/
        ADCCON = ADCCON & (~(0xFF << 6)) | (0x13 << 6);
        /***正常模式 关闭待机****/
        ADCCON = ADCCON & (~(0x1 << 2));

        /**
        * 寄存器配置方式2
        */
        //    ADCCON = (0x1<<16) | (0x1<<14) | (0xff<<6) | 0x1<<1;
        //    必须先读一次寄存器的值，才能激活AD
        //    temp_adc = ADCDAT & 0xFFF;
        return ;
}

void adc_Converter_Value ()
{
        unsigned int temp_adc = 0;
        unsigned int temp_mv = 0;
        while (1)
        {
                /***打开AD开始转换***/
                ADCCON = ADCCON & (~(0x1 << 0)) | (0x1 << 0);
                delay_ms(10);
                /***等待转换完成***/
                while (!(ADCCON & (1 << 15)))
                ;
                /***读取转换结果***/
                temp_adc = ADCDAT & 0xFFF;

                /***将读出来的数据进行格式转换 ***/
                /*(精度是12位，所以是4096，单位mV,提高准确性)*/
                temp_mv = 1800 * temp_adc / 4096;

                printf("adc value: %d mv\n", temp_mv);
                delay_ms(1000);
        }
}