/**************************************************************************//**
 * @file     main.c
 * @version  V1.00
 * @brief    Use the timer TM0 pin to demonstrate inter timer trigger mode
 *           function. Also display the measured input frequency to UART console.
 *
 * SPDX-License-Identifier: Apache-2.0
 * @copyright (C) 2018 Nuvoton Technology Corp. All rights reserved.
 ****************************************************************************/
#include <stdio.h>
#include "NuMicro.h"


int volatile complete = 0;

/* Timer 0 is working in event count mode, and Timer 1 in capture mode, so we read the */
/* capture value from Timer 1, _not_ timer 0. */
void TMR1_IRQHandler(void)
{
    /* TIMER1 clock source = PCLK0 = HCLK / 2 = HIRC / 2 */
    /* Timer clock is 24 MHz, counter value records the duration for 100 event counts. */
    printf("Event frequency is %d Hz\n", (__HIRC/2) / TIMER1->CNT * 100);
    TIMER1->EINTSTS = TIMER_EINTSTS_CAPIF_Msk;
    complete = 1;
}

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

    /* Enable HIRC */
    CLK->PWRCTL |= CLK_PWRCTL_HIRCEN_Msk;

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

    /* Switch HCLK clock source to HIRC */
    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 both PCLK0 and PCLK1 as HCLK/2 */
    CLK->PCLKDIV = (CLK_PCLKDIV_APB0DIV_DIV2 | CLK_PCLKDIV_APB1DIV_DIV2);

    /* Switch UART0 clock source to HIRC */
    CLK->CLKSEL1 = (CLK->CLKSEL1 & ~CLK_CLKSEL1_UART0SEL_Msk) | CLK_CLKSEL1_UART0SEL_HIRC;
    CLK->CLKDIV0 = (CLK->CLKDIV0 & ~CLK_CLKDIV0_UART0DIV_Msk) | CLK_CLKDIV0_UART0(1);

    /* Enable UART0 and Timer peripheral clock */
    CLK->APBCLK0 |= (CLK_APBCLK0_UART0CKEN_Msk | CLK_APBCLK0_TMR0CKEN_Msk | CLK_APBCLK0_TMR1CKEN_Msk);

    /* Select IP clock source */
    CLK->CLKSEL1 = (CLK->CLKSEL1 & ~(CLK_CLKSEL1_TMR0SEL_Msk | CLK_CLKSEL1_TMR1SEL_Msk)) |
                   (CLK_CLKSEL1_TMR0SEL_PCLK0 | CLK_CLKSEL1_TMR1SEL_PCLK0);

    /* 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);

    /* Set timer event counting pin */
    SYS->GPB_MFPL = (SYS->GPB_MFPL & ~(SYS_GPB_MFPL_PB5MFP_Msk)) |
                    (SYS_GPB_MFPL_PB5MFP_TM0);

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

/*----------------------------------------------------------------------*/
/* Init UART0                                                           */
/*----------------------------------------------------------------------*/
void UART0_Init(void)
{
    /* 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(__HIRC, 115200);
    UART0->LINE = UART_WORD_LEN_8 | UART_PARITY_NONE | UART_STOP_BIT_1;
}

int main(void)
{
    int volatile i;

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

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

    /* This sample code demonstrate inter timer trigger mode using Timer0 and Timer1
     * In this mode, Timer0 is working as counter, and triggers Timer1. Using Timer1
     * to calculate the amount of time used by Timer0 to count specified amount of events.
     * By dividing the time period recorded in Timer1 by the event counts, we get
     * the event frequency.
     */
    printf("Inter timer trigger mode demo code\n");
    printf("Please connect input source with Timer 0 counter pin PB.5, press any key to continue\n");
    getchar();

    /* Update prescale and compare value. Calculate average frequency every 100 events */
    TIMER0->CTL = (TIMER0->CTL & ~(TIMER_CTL_OPMODE_Msk | TIMER_CTL_PSC_Msk)) |
                  (TIMER_ONESHOT_MODE);
    TIMER0->CMP = 100;

    /* Update Timer 1 prescale value. So Timer 0 clock is 24MHz */
    TIMER1->CTL = (TIMER1->CTL & ~TIMER_CTL_PSC_Msk) | 0;

    /* We need capture interrupt */
    NVIC_EnableIRQ(TMR1_IRQn);

    while(1)
    {
        complete = 0;

        /* Count event by timer 0, disable drop count (set to 0), disable timeout (set to 0). Enable interrupt after complete */
        TIMER1->CMP = TIMER_CMP_MAX_VALUE;
        TIMER1->EXTCTL = TIMER_EXTCTL_CAPIEN_Msk;
        TIMER0->CTL = (TIMER_CTL_INTRGEN_Msk | TIMER_CTL_CNTEN_Msk);

        while(complete == 0);
    }
}
