PWM下的ADC采样

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

 * [url=home.php?mod=space&uid=288409]@file[/url]     main.c

 * [url=home.php?mod=space&uid=895143]@version[/url]  V0.10

 * $Revision: 2 $

 * $Date: 14/01/28 11:43a $

 * [url=home.php?mod=space&uid=247401]@brief[/url]    ADC and PWM sample for M051 learning board

 *

 * @note

 * Copyright (C) 2014 Nuvoton Technology Corp. All rights reserved.

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

#include <stdio.h>

#include "M051Series.h"

#include "lcd_driver.h"



void SYS_Init(void)

{

    /*---------------------------------------------------------------------------------------------------------*/

    /* Init System Clock                                                                                       */

    /*---------------------------------------------------------------------------------------------------------*/



    /* Unlock protected registers */

    SYS_UnlockReg();



    /* Enable ADC and PWM23 clock */

    CLK->APBCLK = CLK_APBCLK_PWM23_EN_Msk | CLK_APBCLK_ADC_EN_Msk;



    /* ADC clock source is 22.1184MHz, set divider to (3 + 1), ADC clock is 22.1184/4 MHz */

    CLK->CLKDIV |= (3 << CLK_CLKDIV_ADC_N_Pos);



    /* Update System Core Clock */

    /* User can use SystemCoreClockUpdate() to calculate SystemCoreClock and CycylesPerUs automatically. */

    SystemCoreClockUpdate();



    /*---------------------------------------------------------------------------------------------------------*/

    /* Init I/O Multi-function                                                                                 */

    /*---------------------------------------------------------------------------------------------------------*/

    /* Set P4.3 to PWM3 function */

    SYS->P4_MFP = SYS_MFP_P43_PWM3;

    /* Set P1.0 to AIN0 function */

    SYS->P1_MFP = SYS_MFP_P10_AIN0;



    /* Disable digital input path of analog pin AIN0 to prevent leakage */

    P1->OFFD |= 1 << GPIO_OFFD_OFFD_Pos;



    /* Lock protected registers */

    SYS_LockReg();

}





void PWM_Init(void)

{

    /* Set PWM 3 clock prescale to 60, and divider to 1*/

    PWMA->PPR = 60 << PWM_PPR_CP23_Pos;

    PWMA->CSR = PWM_CLK_DIV_1 << PWM_CSR_CSR3_Pos;



    /* Enable PWM3 and set to auto-reload mode.

       Configure PWM mode before setting CNR, CMR. Otherwise CNR will be reset */

    PWMA->PCR = PWM_PCR_CH3EN_Msk | PWM_PCR_CH3MOD_Msk;

    /* PWM 3 frequency = HCLK / (prescale * divider * (CNR + 1))

       PWM 3 duty ratio = (CMR + 1) / (CNR + 1) */

    PWMA->CNR3 = 1843 - 1;

    PWMA->CMR3 = 1833 - 1;



    /* Enable PWM3 Output */

    PWMA->POE = PWM_POE_PWM3_Msk;



}



void ADC_Init(void)

{

    /* Set to convert ADC channel 0 */

    ADC->ADCHER = 0x1;

    /* Enable the ADC converter */

    ADC->ADCR = ADC_ADCR_ADEN_Msk;



}



/* Main function  */

int main(void)

{

    uint32_t u32Data, u32Sum, u32Count;

    char adc_value[20];



    /* Init System, IP clock and multi-function I/O

       In the end of SYS_Init() will issue SYS_LockReg()

       to lock protected register. If user want to write

       protected register, please issue SYS_UnlockReg()

       to unlock protected register if necessary */

    SYS_Init();



    /* Initial LCD panel. SPI clock and interface is configured in this function. */

    LCD_Init();

    /* Clear LCD screen. Do this before turn back light on */

    LCD_ClearScreen();

    /* Enable LCD back light */

    LCD_EnableBackLight();

    /* Show messages on LCD */

    LCD_Print(0, "ADC_PWM");

    LCD_Print(1, "Sample code");

    LCD_Print(2, "ADC Value:");



    /* Init PWM channel 3 */

    PWM_Init();



    /* Init ADC to get the value of variable resistor */

    ADC_Init();



    u32Count = 0;

    u32Sum = 0;



    while(1)

    {

        /* Start convert */

        ADC_START_CONV(ADC);



        /* Waiting for convert complete */

        while(ADC_IS_BUSY(ADC));



        /* Read the result from ADC */

        u32Data = ADC->ADDR[0] & ADC_ADDR_RSLT_Msk;



        /* Determine the sum */

        u32Sum += u32Data;

        u32Count++;

        if(u32Count == 128)

        {

            /* Determine the average */

            u32Data = u32Sum / 128;

            /* Update the average ADC conversion result to LCD */

            sprintf(adc_value, "          %4d", u32Data);

            LCD_Print(3, adc_value);

            /* Adjust the duty cycle of PWM3 according to the average ADC value. */

            PWMA->CMR3 = (u32Data * PWMA->CNR3) / 4096;

            /* Reset count and sum */

            u32Count = 0;

            u32Sum = 0;

        }

    }

}



/*** (C) COPYRIGHT 2014 Nuvoton Technology Corp. ***/