/**************************************************************************//**
 * @file     main.c
 * @version  V3.00
 * @brief    Demonstrate how to wake up system from Power-down mode by brown-out detector interrupt.
 *
 * SPDX-License-Identifier: Apache-2.0
 * @copyright (C) 2020 Nuvoton Technology Corp. All rights reserved.
 ******************************************************************************/
#include "stdio.h"
#include "NuMicro.h"


/*---------------------------------------------------------------------------------------------------------*/
/*  Function for System Entry to Power Down Mode                                                           */
/*---------------------------------------------------------------------------------------------------------*/
void PowerDownFunction(void)
{
    /* Check if all the debug messages are finished */
    UART_WAIT_TX_EMPTY(UART0);

    /* Enable Power-down mode wake-up interrupt */
    CLK->PWRCTL |= CLK_PWRCTL_PDWKIEN_Msk;

    /* Enter to Power-down mode */
    CLK_PowerDown();
}


/*---------------------------------------------------------------------------------------------------------*/
/*  Brown Out Detector IRQ Handler                                                                         */
/*---------------------------------------------------------------------------------------------------------*/
void BOD_IRQHandler(void)
{
    /* Clear BOD Interrupt Flag */
    SYS_CLEAR_BOD_INT_FLAG();

    printf("Brown Out is Detected.\n");
}


/*---------------------------------------------------------------------------------------------------------*/
/*  Power-down Mode Wake-up IRQ Handler                                                                    */
/*---------------------------------------------------------------------------------------------------------*/
void PWRWU_IRQHandler(void)
{
    /* Check system power down mode wake-up interrupt status flag */
    if(CLK->PWRCTL & CLK_PWRCTL_PDWKIF_Msk)
    {
        /* Clear system power down wake-up interrupt flag */
        CLK->PWRCTL |= CLK_PWRCTL_PDWKIF_Msk;

        printf("System wake-up from Power-down mode.\n");
    }
}


void SYS_Init(void)
{
    /* Unlock protected registers */
    SYS_UnlockReg();

    /* Enable HIRC */
    CLK_EnableXtalRC(CLK_PWRCTL_HIRCEN_Msk);

    /* Waiting for HIRC clock ready */
    CLK_WaitClockReady(CLK_STATUS_HIRCSTB_Msk);

    /* Switch HCLK clock source to HIRC */
    CLK_SetHCLK(CLK_CLKSEL0_HCLKSEL_HIRC, CLK_CLKDIV0_HCLK(1));

    /* Set both PCLK0 and PCLK1 as HCLK/2 */
    CLK->PCLKDIV = (CLK_PCLKDIV_APB0DIV_DIV2 | CLK_PCLKDIV_APB1DIV_DIV2);

    /* Switch UART0 clock source to HIRC */
    CLK_SetModuleClock(UART0_MODULE, CLK_CLKSEL1_UART0SEL_HIRC, CLK_CLKDIV0_UART0(1));

    /* Enable UART peripheral clock */
    CLK_EnableModuleClock(UART0_MODULE);

    /* Update System Core Clock */
    /* User can use SystemCoreClockUpdate() to calculate PllClock, SystemCoreClock and CycylesPerUs automatically. */
    SystemCoreClockUpdate();

    /*----------------------------------------------------------------------*/
    /* Init I/O Multi-function                                              */
    /*----------------------------------------------------------------------*/
    /* Set PB multi-function pins for UART0 RXD=PB.6 and TXD=PB.4 */
    SYS->GPB_MFP1 = (SYS->GPB_MFP1 & ~(SYS_GPB_MFP1_PB4MFP_Msk | SYS_GPB_MFP1_PB6MFP_Msk)) |
                    (SYS_GPB_MFP1_PB4MFP_UART0_TXD | SYS_GPB_MFP1_PB6MFP_UART0_RXD);

    /* Lock protected registers */
    SYS_LockReg();
}

/*----------------------------------------------------------------------*/
/* 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("\n\nCPU @ %d Hz\n", SystemCoreClock);
    printf("+------------------------------------------------+\n");
    printf("|        Power-down and Wake-up Sample Code      |\n");
    printf("+------------------------------------------------+\n");

    /* Unlock protected registers before setting Brown-out detector function and Power-down mode */
    SYS_UnlockReg();

    /* Enable Brown-out detector function */
    SYS_ENABLE_BOD();

    /* Set Brown-out detector voltage level as 2.7V */
    SYS_SET_BOD_LEVEL(SYS_BODCTL_BODVL_2_7V);

    /* Enable Brown-out detector interrupt function */
    SYS_DISABLE_BOD_RST();

    /* Enable Brown-out detector and Power-down wake-up interrupt */
    NVIC_EnableIRQ(BOD_IRQn);
    NVIC_EnableIRQ(PWRWU_IRQn);

    printf("System enter to Power-down mode.\n");
    printf("System wake-up if VDD voltage is lower than 2.7V.\n\n");

    /* Enter to Power-down mode */
    PowerDownFunction();

    /* Wait for Power-down mode wake-up interrupt happen */
    while(1);
}
