[牛人杂谈] SPI时序详解

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

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

 * [url=home.php?mod=space&uid=895143]@version[/url]  V2.00

 * $Revision: 2 $

 * $Date: 14/12/25 10:24a $

 * @brief

 *           Implement SPI Master loop back transfer. 

 *           This sample code needs to connect SPI0_MISO0 pin and SPI0_MOSI0 pin together. 

 *           It will compare the received data with transmitted data.

 * @note

 * Copyright (C) 2014 Nuvoton Technology Corp. All rights reserved.

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

#include <stdio.h>

#include "M0518.h"



#define TEST_COUNT             64



uint32_t g_au32SourceData[TEST_COUNT];

uint32_t g_au32DestinationData[TEST_COUNT];



/* Function prototype declaration */

void SYS_Init(void);

void SPI_Init(void);



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

/* Main function */

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

int main(void)

{

    uint32_t u32DataCount, u32TestCount, u32Err;



    /* Unlock protected registers */

    SYS_UnlockReg();



    SYS_Init();



    /* Lock protected registers */

    SYS_LockReg();



    /* Configure UART0: 115200, 8-bit word, no parity bit, 1 stop bit. */

    UART_Open(UART0, 115200);



    /* Init SPI */

    SPI_Init();



    printf("\n\n");

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

    printf("|                   M0518 SPI Driver Sample Code                    |\n");

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

    printf("\n");

    printf("\nThis sample code demonstrates SPI0 self loop back data transfer.\n");

    printf(" SPI0 configuration:\n");

    printf("     Master mode; data width 32 bits.\n");

    printf(" I/O connection:\n");

    printf("     PC.3 SPI0_MOSI0 <--> PC.2 SPI0_MISO0 \n");



    printf("\nSPI0 Loopback test ");



    u32Err = 0;

    for(u32TestCount = 0; u32TestCount < 0x1000; u32TestCount++)

    {

        /* set the source data and clear the destination buffer */

        for(u32DataCount = 0; u32DataCount < TEST_COUNT; u32DataCount++)

        {

            g_au32SourceData[u32DataCount] = u32DataCount;

            g_au32DestinationData[u32DataCount] = 0;

        }



        u32DataCount = 0;



        if((u32TestCount & 0x1FF) == 0)

        {

            putchar('.');

        }



        while(1)

        {

            /* Write to TX register */

            SPI_WRITE_TX(SPI0, g_au32SourceData[u32DataCount]);

            /* Trigger SPI data transfer */

            SPI_TRIGGER(SPI0);

            /* Check SPI0 busy status */

            while(SPI_IS_BUSY(SPI0));

            /* Read received data */

            g_au32DestinationData[u32DataCount] = SPI_READ_RX(SPI0);

            u32DataCount++;

            if(u32DataCount > TEST_COUNT)

                break;

        }



        /*  Check the received data */

        for(u32DataCount = 0; u32DataCount < TEST_COUNT; u32DataCount++)

        {

            if(g_au32DestinationData[u32DataCount] != g_au32SourceData[u32DataCount])

                u32Err = 1;

        }



        if(u32Err)

            break;

    }



    if(u32Err)

        printf(" [FAIL]\n\n");

    else

        printf(" [PASS]\n\n");



    /* Close SPI0 */

    SPI_Close(SPI0);



    while(1);

}



void SYS_Init(void)

{



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

    /* Init System Clock                                                                                       */

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



    /* Enable external 12MHz XTAL */

    CLK_EnableXtalRC(CLK_PWRCON_XTL12M_EN_Msk);



    /* Waiting for clock ready */

    CLK_WaitClockReady(CLK_CLKSTATUS_XTL12M_STB_Msk);



    /* Switch HCLK clock source to HXT and HCLK source divide 1 */

    CLK_SetHCLK(CLK_CLKSEL0_HCLK_S_HXT, CLK_CLKDIV_HCLK(1));



    /* Select HXT as the clock source of UART0 */

    CLK_SetModuleClock(UART0_MODULE, CLK_CLKSEL1_UART_S_HXT, CLK_CLKDIV_UART(1));



    /* Select HCLK as the clock source of SPI0 */

    CLK_SetModuleClock(SPI0_MODULE, CLK_CLKSEL1_SPI0_S_HCLK, MODULE_NoMsk);



    /* Enable UART peripheral clock */

    CLK_EnableModuleClock(UART0_MODULE);

    /* Enable SPI0 peripheral clock */

    CLK_EnableModuleClock(SPI0_MODULE);



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

    /* Init I/O Multi-function                                                                                 */

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



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

    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_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_SPI0_SS0 | SYS_ALT_MFP_PC1_SPI0_CLK | SYS_ALT_MFP_PC2_SPI0_MISO0 | SYS_ALT_MFP_PC3_SPI0_MOSI0;



    /* Update System Core Clock */

    /* User can use SystemCoreClockUpdate() to calculate SystemCoreClock and CyclesPerUs automatically. */

    SystemCoreClockUpdate();

}



void SPI_Init(void)

{

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

    /* Init SPI                                                                                                */

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

    /* Configure as a master, clock idle low, 32-bit transaction, drive output on falling clock edge and latch input on rising edge. */

    /* Set IP clock divider. SPI clock rate = 2MHz */

    SPI_Open(SPI0, SPI_MASTER, SPI_MODE_0, 32, 2000000);



    /* Enable the automatic hardware slave select function. Select the SS pin and configure as low-active. */

    SPI_EnableAutoSS(SPI0, SPI_SS0, SPI_SS_ACTIVE_LOW);

}



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