/**************************************************************************//**
 * @file     main.c
 * @version  V3.00
 * $Revision: 2 $
 * $Date: 16/10/25 4:27p $
 * @brief
 *           Show how to wake up system form Power-down mode by brown-out detector interrupt.
 *
 * @note
 * Copyright (C) 2016 Nuvoton Technology Corp. All rights reserved.
 *
 ******************************************************************************/
#include "stdio.h"
#include "NUC126.h"

#define PLLCTL_SETTING  CLK_PLLCTL_72MHz_HXT
#define PLL_CLOCK       72000000


/*---------------------------------------------------------------------------------------------------------*/
/*  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;

    /* Set the processor is deep sleep as its low power mode */
    SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;

    /* Set system Power-down enabled */
    CLK->PWRCTL |= CLK_PWRCTL_PDEN_Msk;

    /* Chip enter Power-down mode after CPU run WFI instruction */
    __WFI();

}

/*---------------------------------------------------------------------------------------------------------*/
/*  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)
{

    /*---------------------------------------------------------------------------------------------------------*/
    /* Init System Clock                                                                                       */
    /*---------------------------------------------------------------------------------------------------------*/

    /* Enable HIRC clock (Internal RC 22.1184MHz) */
    CLK->PWRCTL |= CLK_PWRCTL_HIRCEN_Msk;

    /* Wait for HIRC clock ready */
    while(!(CLK->STATUS & CLK_STATUS_HIRCSTB_Msk));

    /* Select HCLK clock source as HIRC and HCLK clock divider as 1 */
    CLK->CLKSEL0 = (CLK->CLKSEL0 & (~CLK_CLKSEL0_HCLKSEL_Msk)) | CLK_CLKSEL0_HCLKSEL_HIRC;
    CLK->CLKDIV0 = (CLK->CLKDIV0 & (~CLK_CLKDIV0_HCLKDIV_Msk)) | CLK_CLKDIV0_HCLK(1);

    /* Set PLL to Power-down mode */
    CLK->PLLCTL |= CLK_PLLCTL_PD_Msk;

    /* Enable HXT clock (external XTAL 12MHz) */
    CLK->PWRCTL |= CLK_PWRCTL_HXTEN_Msk;

    /* Wait for HXT clock ready */
    while(!(CLK->STATUS & CLK_STATUS_HXTSTB_Msk));

    /* Set core clock as PLL_CLOCK from PLL */
    CLK->PLLCTL = PLLCTL_SETTING;
    while(!(CLK->STATUS & CLK_STATUS_PLLSTB_Msk));
    CLK->CLKSEL0 = (CLK->CLKSEL0 & (~CLK_CLKSEL0_HCLKSEL_Msk)) | CLK_CLKSEL0_HCLKSEL_PLL;

    /* Update System Core Clock */
    PllClock        = PLL_CLOCK;            // PLL
    SystemCoreClock = PLL_CLOCK / 1;        // HCLK
    CyclesPerUs     = PLL_CLOCK / 1000000;  // For CLK_SysTickDelay()

    /* Enable UART module clock */
    CLK->APBCLK0 |= CLK_APBCLK0_UART0CKEN_Msk;

    /* Select UART module clock source as HXT and UART module clock divider as 1 */
    CLK->CLKSEL1 = (CLK->CLKSEL1 & (~CLK_CLKSEL1_UARTSEL_Msk)) | CLK_CLKSEL1_UARTSEL_HXT;
    CLK->CLKDIV0 = (CLK->CLKDIV0 & (~CLK_CLKDIV0_UARTDIV_Msk)) | CLK_CLKDIV0_UART(1);

    /*---------------------------------------------------------------------------------------------------------*/
    /* Init I/O Multi-function                                                                                 */
    /*---------------------------------------------------------------------------------------------------------*/

    /* Set PD multi-function pins for UART0 RXD(PD.0) and TXD(PD.1) */
    SYS->GPD_MFPL = (SYS->GPD_MFPL & (~SYS_GPD_MFPL_PD0MFP_Msk)) | SYS_GPD_MFPL_PD0MFP_UART0_RXD;
    SYS->GPD_MFPL = (SYS->GPD_MFPL & (~SYS_GPD_MFPL_PD1MFP_Msk)) | SYS_GPD_MFPL_PD1MFP_UART0_TXD;

    /* Set PC multi-function pins for CLKO(PC.1) */
    SYS->GPC_MFPL = (SYS->GPC_MFPL & (~SYS_GPC_MFPL_PC1MFP_Msk)) | SYS_GPC_MFPL_PC1MFP_CLKO;

}

void UART0_Init()
{
    /*---------------------------------------------------------------------------------------------------------*/
    /* Init UART                                                                                               */
    /*---------------------------------------------------------------------------------------------------------*/
    /* Reset UART0 */
    SYS->IPRST1 |=  SYS_IPRST1_UART0RST_Msk;
    SYS->IPRST1 &= ~SYS_IPRST1_UART0RST_Msk;

    /* Configure UART0 and set UART0 baud rate */
    UART0->BAUD = UART_BAUD_MODE2 | UART_BAUD_MODE2_DIVIDER(__HXT, 115200);
    UART0->LINE = UART_WORD_LEN_8 | UART_PARITY_NONE | UART_STOP_BIT_1;
}

/*---------------------------------------------------------------------------------------------------------*/
/*  Main Function                                                                                          */
/*---------------------------------------------------------------------------------------------------------*/
int32_t main(void)
{

    /* Unlock protected registers */
    SYS_UnlockReg();

    /* Init System, peripheral clock and multi-function I/O */
    SYS_Init();

    /* Lock protected registers */
    SYS_LockReg();

    /* Init UART0 for printf */
    UART0_Init();

    printf("\n\nCPU @ %d Hz\n", SystemCoreClock);
    printf("+-------------------------------------------------+\n");
    printf("|    NUC126 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);

}

