/**************************************************************************//**
 * @file     main.c
 * @version  V2.0
 * $Revision: 9 $
 * $Date: 15/01/16 1:45p $
 * @brief
 *           Configure SPI0 as Slave mode and demonstrate how to communicate with an off-chip SPI Master device.
 *           This sample code needs to work with SPI_MasterFifoMode sample code.
 * @note
 * Copyright (C) 2014 Nuvoton Technology Corp. All rights reserved.
 *
 ******************************************************************************/
#include <stdio.h>
#include "NUC131.h"


#define TEST_COUNT 16

uint32_t g_au32SourceData[TEST_COUNT];
uint32_t g_au32DestinationData[TEST_COUNT];
volatile uint32_t g_u32TxDataCount;
volatile uint32_t g_u32RxDataCount;

/* Function prototype declaration */
void SYS_Init(void);
void UART0_Init(void);
void SPI_Init(void);

/* ------------- */
/* Main function */
/* ------------- */
int main(void)
{
    volatile uint32_t u32TxDataCount, u32RxDataCount;

    /* Unlock protected registers */
    SYS_UnlockReg();

    SYS_Init();

    /* Lock protected registers */
    SYS_LockReg();

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

    /* Init SPI */
    SPI_Init();

    printf("\n\n");
    printf("+-----------------------------------------------------+\n");
    printf("|           SPI Slave Mode Sample Code                |\n");
    printf("+-----------------------------------------------------+\n");
    printf("\n");
    printf("Configure SPI0 as a slave.\n");
    printf("Bit length of a transaction: 32\n");
    printf("The I/O connection for SPI0:\n");
    printf("    SPI0_SS0 (PC.0)\n    SPI0_CLK (PC.1)\n");
    printf("    SPI0_MISO0 (PC.2)\n    SPI0_MOSI0 (PC.3)\n\n");
    printf("SPI controller will enable FIFO mode and transfer %d data to a off-chip master device.\n", TEST_COUNT);
    printf("In the meanwhile the SPI controller will receive %d data from the off-chip master device.\n", TEST_COUNT);
    printf("After the transfer is done, the %d received data will be printed out.\n", TEST_COUNT);

    for(u32TxDataCount = 0; u32TxDataCount < TEST_COUNT; u32TxDataCount++)
    {
        /* Write the initial value to source buffer */
        g_au32SourceData[u32TxDataCount] = 0x00AA0000 + u32TxDataCount;
        /* Clear destination buffer */
        g_au32DestinationData[u32TxDataCount] = 0;
    }

    u32TxDataCount = 0;
    u32RxDataCount = 0;
    printf("Press any key if the master device configuration is ready.\n");
    getchar();
    printf("\n");

    /* Access TX and RX FIFO */
    while(u32RxDataCount < TEST_COUNT)
    {
        /* Check TX FULL flag and TX data count */
        if(((SPI0->STATUS & SPI_STATUS_TX_FULL_Msk) == 0) && (u32TxDataCount < TEST_COUNT))
            SPI0->TX = g_au32SourceData[u32TxDataCount++]; /* Write to TX FIFO */
        /* Check RX EMPTY flag */
        if((SPI0->STATUS & SPI_STATUS_RX_EMPTY_Msk) == 0)
            g_au32DestinationData[u32RxDataCount++] = SPI0->RX; /* Read RX FIFO */
    }

    /* Print the received data */
    printf("Received data:\n");
    for(u32RxDataCount = 0; u32RxDataCount < TEST_COUNT; u32RxDataCount++)
    {
        printf("%d:\t0x%X\n", u32RxDataCount, g_au32DestinationData[u32RxDataCount]);
    }
    printf("The data transfer was done.\n");

    printf("\n\nExit SPI driver sample code.\n");

    /* Disable SPI0 peripheral clock */
    CLK->APBCLK &= (~CLK_APBCLK_SPI0_EN_Msk);
    while(1);
}

void SYS_Init(void)
{
    /*---------------------------------------------------------------------------------------------------------*/
    /* Init System Clock                                                                                       */
    /*---------------------------------------------------------------------------------------------------------*/

    /* Enable external 12MHz XTAL */
    CLK->PWRCON |= CLK_PWRCON_XTL12M_EN_Msk;

    /* Waiting for clock ready */
    while(!(CLK->CLKSTATUS & CLK_CLKSTATUS_XTL12M_STB_Msk));

    /* Select HXT as the clock source of HCLK */
    CLK->CLKSEL0 = (CLK->CLKSEL0 & (~CLK_CLKSEL0_HCLK_S_Msk)) | CLK_CLKSEL0_HCLK_S_HXT;

    /* Select HXT as the clock source of UART; select HCLK as the clock source of SPI0. */
    CLK->CLKSEL1 = (CLK->CLKSEL1 & (~(CLK_CLKSEL1_UART_S_Msk | CLK_CLKSEL1_SPI0_S_Msk))) | (CLK_CLKSEL1_UART_S_HXT | CLK_CLKSEL1_SPI0_S_HCLK);

    /* Enable UART0 and SPI0 clock */
    CLK->APBCLK = CLK_APBCLK_UART0_EN_Msk | CLK_APBCLK_SPI0_EN_Msk;

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

    /*---------------------------------------------------------------------------------------------------------*/
    /* Init I/O Multi-function                                                                                 */
    /*---------------------------------------------------------------------------------------------------------*/
    /* Set PB multi-function pins for UART0 RXD and TXD */
    SYS->GPB_MFP &= ~(SYS_GPB_MFP_PB0_Msk | SYS_GPB_MFP_PB1_Msk);
    SYS->GPB_MFP |= (SYS_GPB_MFP_PB0_UART0_RXD | SYS_GPB_MFP_PB1_UART0_TXD);

    /* Setup SPI0 multi-function pins */
    SYS->GPC_MFP &= ~(SYS_GPC_MFP_PC0_Msk | SYS_GPC_MFP_PC1_Msk | SYS_GPC_MFP_PC2_Msk | SYS_GPC_MFP_PC3_Msk);
    SYS->GPC_MFP |= (SYS_GPC_MFP_PC0_SPI0_SS0 | SYS_GPC_MFP_PC1_SPI0_CLK | SYS_GPC_MFP_PC2_SPI0_MISO0 | SYS_GPC_MFP_PC3_SPI0_MOSI0);
    SYS->ALT_MFP &= ~(SYS_ALT_MFP_PC0_Msk | SYS_ALT_MFP_PC1_Msk | SYS_ALT_MFP_PC2_Msk | SYS_ALT_MFP_PC3_Msk);
    SYS->ALT_MFP |= (SYS_ALT_MFP_PC0_SPI0_SS0 | SYS_ALT_MFP_PC1_SPI0_CLK | SYS_ALT_MFP_PC2_SPI0_MISO0 | SYS_ALT_MFP_PC3_SPI0_MOSI0);
}

void UART0_Init(void)
{
    /* Word length is 8 bits; 1 stop bit; no parity bit. */
    UART0->LCR = UART_LCR_WLS_Msk;
    /* Using mode 2 calculation: UART bit rate = UART peripheral clock rate / (BRD setting + 2) */
    /* UART peripheral clock rate 12MHz; UART bit rate 115200 bps. */
    /* 12000000 / 115200 bps ~= 104 */
    /* 104 - 2 = 0x66. */
    UART0->BAUD = UART_BAUD_DIV_X_EN_Msk | UART_BAUD_DIV_X_ONE_Msk | (0x66);
}

void SPI_Init(void)
{
    /*---------------------------------------------------------------------------------------------------------*/
    /* Init SPI                                                                                                */
    /*---------------------------------------------------------------------------------------------------------*/
    /* Configure SPI0 as a slave, clock idle low, 32-bit transaction, drive output on falling clock edge and latch input on rising edge. */
    SPI0->CNTRL = SPI_CNTRL_FIFO_Msk | SPI_CNTRL_SLAVE_Msk | SPI_CNTRL_TX_NEG_Msk;
    /* Configure SPI0 as a low level active device. */
    SPI0->SSR = SPI_SSR_SS_LTRIG_Msk;
    /* Set IP clock divider. SPI peripheral clock rate = HCLK / 2 = 6MHz */
    SPI0->DIVIDER = 0;
}

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


