說說M451例程講解之串口

/**************************************************************************//** * @file main.c * @version V3.00 * $Revision: 3 $ * $Date: 15/09/02 10:03a $ * @brief Demonstrate how to set GPIO pin mode and use pin data input/output control. * @note * Copyright (C) 2013~2015 Nuvoton Technology Corp. All rights reserved. * ******************************************************************************/ #include "stdio.h" #include "M451Series.h"


#define PLL_CLOCK       72000000


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

    /* Enable HIRC clock (Internal RC 22.1184MHz) */ CLK_EnableXtalRC(CLK_PWRCTL_HIRCEN_Msk); /* Wait for HIRC clock ready */ CLK_WaitClockReady(CLK_STATUS_HIRCSTB_Msk); /* Select HCLK clock source as HIRC and and HCLK clock divider as 1 */ CLK_SetHCLK(CLK_CLKSEL0_HCLKSEL_HIRC, CLK_CLKDIV0_HCLK(1)); /* Enable HXT clock (external XTAL 12MHz) */ CLK_EnableXtalRC(CLK_PWRCTL_HXTEN_Msk); /* Wait for HXT clock ready */ CLK_WaitClockReady(CLK_STATUS_HXTSTB_Msk); /* Set core clock as PLL_CLOCK from PLL */ CLK_SetCoreClock(PLL_CLOCK); /* Enable UART module clock */ CLK_EnableModuleClock(UART0_MODULE); /* Select UART module clock source as HXT and UART module clock divider as 1 */ CLK_SetModuleClock(UART0_MODULE, CLK_CLKSEL1_UARTSEL_HIRC, CLK_CLKDIV0_UART(1)); /*---------------------------------------------------------------------------------------------------------*/
    /* Init I/O Multi-function */
    /*---------------------------------------------------------------------------------------------------------*/

    /* Set PD multi-function pins for UART0 RXD(PD.6) and TXD(PD.1) */ SYS->GPD_MFPL &= ~(SYS_GPD_MFPL_PD6MFP_Msk | SYS_GPD_MFPL_PD1MFP_Msk); SYS->GPD_MFPL |= (SYS_GPD_MFPL_PD6MFP_UART0_RXD | SYS_GPD_MFPL_PD1MFP_UART0_TXD); } void UART0_Init() { /*---------------------------------------------------------------------------------------------------------*/
    /* Init UART */
    /*---------------------------------------------------------------------------------------------------------*/
    /* Reset UART module */ SYS_ResetModule(UART0_RST); /* Configure UART0 and set UART0 baud rate */ UART_Open(UART0, 115200); } /*---------------------------------------------------------------------------------------------------------*/
/* Main Function */
/*---------------------------------------------------------------------------------------------------------*/ int32_t main(void) { uint8_t a[]={'a','b','c','\n'}; /* 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(); UART_Write(UART0,a,5); UART_READ(UART0); printf("\n\nCPU @ %dHz\n", SystemCoreClock); printf("UART test\n\r"); while(1); }