如何通过使用片上基准电压（band-gap）来计算电池电压（AVdd）

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

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

 * [url=home.php?mod=space&uid=895143]@version[/url]  V3.00

 * [url=home.php?mod=space&uid=247401]@brief[/url]    Demonstrate how to calculate battery voltage( AVdd ) by using band-gap.

 *

 * SPDX-License-Identifier: Apache-2.0

 * [url=home.php?mod=space&uid=17282]@CopyRight[/url] (C) 2018 Nuvoton Technology Corp. All rights reserved.

 *

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

#include <stdio.h>

#include "NuMicro.h"





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

/* Define global variables and constants                                                                   */

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

volatile uint32_t g_u32AdcIntFlag;

volatile uint32_t g_u32BandGapConvValue;



/**

  * @brief      Read Built-in Band-Gap conversion value

  * @param[in]  None

  * [url=home.php?mod=space&uid=266161]@return[/url]     Built-in Band-Gap conversion value

  * [url=home.php?mod=space&uid=1543424]@Details[/url]    This function is used to read Band-Gap conversion value.

  */

__STATIC_INLINE uint32_t FMC_ReadBandGap(void)

{

    FMC->ISPCMD = FMC_ISPCMD_READ_UID;            /* Set ISP Command Code */

    FMC->ISPADDR = 0x70u;                         /* Must keep 0x70 when read Band-Gap */

    FMC->ISPTRG = FMC_ISPTRG_ISPGO_Msk;           /* Trigger to start ISP procedure */

#if ISBEN

    __ISB();

#endif                                            /* To make sure ISP/CPU be Synchronized */

    while(FMC->ISPTRG & FMC_ISPTRG_ISPGO_Msk) {}  /* Waiting for ISP Done */



    return FMC->ISPDAT & 0xFFF;

}



void SYS_Init(void)

{

    /* Unlock protected registers */

    SYS_UnlockReg();



    /* Enable HIRC clock (Internal RC 48 MHz) */

    CLK_EnableXtalRC(CLK_PWRCTL_HIRCEN_Msk);



    /* Wait for HIRC clock ready */

    CLK_WaitClockReady(CLK_STATUS_HIRCSTB_Msk);



    /* Select HCLK clock source as HIRC and HCLK source divider as 1 */

    CLK_SetHCLK(CLK_CLKSEL0_HCLKSEL_HIRC, CLK_CLKDIV0_HCLK(1));



    /* Enable module clock */

    CLK_EnableModuleClock(UART0_MODULE);

    CLK_EnableModuleClock(ADC_MODULE);



    /* Switch UART0 clock source to HIRC */

    CLK_SetModuleClock(UART0_MODULE, CLK_CLKSEL1_UART0SEL_HIRC, CLK_CLKDIV0_UART0(1));

    /* Switch ADC clock source to HIRC, set divider to 2, ADC clock is 48/2 MHz */

    CLK_SetModuleClock(ADC_MODULE, CLK_CLKSEL2_ADCSEL_PCLK1, CLK_CLKDIV0_ADC(2));



    /* Update System Core Clock */

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

    SystemCoreClockUpdate();



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

    /* Init I/O Multi-function                                              */

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



    /* Set GPB multi-function pins for UART0 RXD and TXD */

    SYS->GPB_MFPH = (SYS->GPB_MFPH & ~(SYS_GPB_MFPH_PB12MFP_Msk | SYS_GPB_MFPH_PB13MFP_Msk)) |

                    (SYS_GPB_MFPH_PB12MFP_UART0_RXD | SYS_GPB_MFPH_PB13MFP_UART0_TXD);



    /* Lock protected registers */

    SYS_LockReg();

}



void ADC_FunctionTest()

{

    int32_t  i32ConversionData;

    int32_t  i32BuiltInData;



    printf("\n");

    printf("+----------------------------------------------------------------------------+\n");

    printf("|     ADC for calculate battery voltage( AVdd ) by using band-gap test       |\n");

    printf("+----------------------------------------------------------------------------+\n\n");



    printf("+----------------------------------------------------------------------+\n");

    printf("|   ADC clock source -> PCLK1  = 48 MHz                                |\n");

    printf("|   ADC clock divider          = 2                                     |\n");

    printf("|   ADC clock                  = 48 MHz / 2 = 24 MHz                   |\n");

    printf("|   ADC extended sampling time = 71                                    |\n");

    printf("|   ADC conversion time = 17 + ADC extended sampling time = 88         |\n");

    printf("|   ADC conversion rate = 24 MHz / 88 = 272.7 ksps                     |\n");

    printf("+----------------------------------------------------------------------+\n");



    /* Enable ADC converter */

    ADC_POWER_ON(ADC);



    /* Set input mode as single-end, Single mode, and select channel 29 (band-gap voltage) */

    ADC_Open(ADC, ADC_ADCR_DIFFEN_SINGLE_END, ADC_ADCR_ADMD_SINGLE, BIT29);



    /* To sample band-gap precisely, the ADC capacitor must be charged at least 3 us for charging the ADC capacitor ( Cin )*/

    /* Sampling time = extended sampling time + 1 */

    /* 1/24000000 * (Sampling time) = 3 us */

    ADC_SetExtendSampleTime(ADC, 0, 71);



    /* Clear the A/D interrupt flag for safe */

    ADC_CLR_INT_FLAG(ADC, ADC_ADF_INT);



    /* Enable the sample module interrupt.  */

    ADC_ENABLE_INT(ADC, ADC_ADF_INT);   // Enable sample module A/D interrupt.

    NVIC_EnableIRQ(ADC_IRQn);



    printf(" Press any key to start the test\n\n");

    getchar();



    /* Reset the ADC interrupt indicator and trigger sample module to start A/D conversion */

    g_u32AdcIntFlag = 0;

    ADC_START_CONV(ADC);



    /* Wait ADC conversion done */

    while(g_u32AdcIntFlag == 0);



    /* Disable the A/D interrupt */

    ADC_DISABLE_INT(ADC, ADC_ADF_INT);



    /* Get the conversion result of the channel 29 */

    i32ConversionData = ADC_GET_CONVERSION_DATA(ADC, 29);





    /* Enable FMC ISP function to read built-in band-gap A/D conversion result*/

    SYS_UnlockReg();

    FMC_Open();

    i32BuiltInData = FMC_ReadBandGap();



    /* Use Conversion result of Band-gap to calculating AVdd */



    printf("      AVdd           i32BuiltInData                   \n");

    printf("   ---------- = -------------------------             \n");

    printf("      3072          i32ConversionData                 \n");

    printf("                                                      \n");

    printf("AVdd =  3072 * i32BuiltInData / i32ConversionData     \n\n");



    printf("Built-in band-gap A/D conversion result: 0x%X (%d) \n", i32BuiltInData, i32BuiltInData);

    printf("Conversion result of Band-gap:           0x%X (%d) \n\n", i32ConversionData, i32ConversionData);



    printf("AVdd = 3072 * %d / %d = %d mV \n\n", i32BuiltInData, i32ConversionData, 3072*i32BuiltInData/i32ConversionData);

}



void ADC_IRQHandler(void)

{

    g_u32AdcIntFlag = 1;

    ADC_CLR_INT_FLAG(ADC, ADC_ADF_INT); /* Clear the A/D interrupt flag */

}



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

/* Init UART0                                                           */

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

void UART0_Init(void)

{

    /* Reset UART0 */

    SYS_ResetModule(UART0_RST);



    /* Configure UART0 and set UART0 baud rate */

    UART_Open(UART0, 115200);

}



int32_t main(void)

{

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

    SYS_Init();



    /* Init UART0 for printf */

    UART0_Init();



    printf("\nSystem clock rate: %d Hz", SystemCoreClock);



    /* ADC function test */

    ADC_FunctionTest();



    /* Disable ADC IP clock */

    CLK_DisableModuleClock(ADC_MODULE);



    /* Disable External Interrupt */

    NVIC_DisableIRQ(ADC_IRQn);



    printf("Exit ADC sample code\n");



    while(1);

}