EK-TM4C123GH6PM-UART2小练--使用官方的库函数

//*****************************************************************************
//
// bitband.c - Bit-band manipulation example.
//
// Copyright (c) 2012-2017 Texas Instruments Incorporated.  All rights reserved.
// Software License Agreement
// 
// Texas Instruments (TI) is supplying this software for use solely and
// exclusively on TI's microcontroller products. The software is owned by
// TI and/or its suppliers, and is protected under applicable copyright
// laws. You may not combine this software with "viral" open-source
// software in order to form a larger program.
// 
// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
// DAMAGES, FOR ANY REASON WHATSOEVER.
// 
// This is part of revision 2.1.4.178 of the EK-TM4C123GXL Firmware Package.
//
//*****************************************************************************

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "inc/hw_gpio.h"
#include "driverlib/debug.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/rom.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"

//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>Bit-Banding (bitband)</h1>
//!
//! This example application demonstrates the use of the bit-banding
//! capabilities of the Cortex-M4F microprocessor.  All of SRAM and all of the
//! peripherals reside within bit-band regions, meaning that bit-banding
//! operations can be applied to any of them.  In this example, a variable in
//! SRAM is set to a particular value one bit at a time using bit-banding
//! operations (it would be more efficient to do a single non-bit-banded write;
//! this simply demonstrates the operation of bit-banding).
//
//*****************************************************************************


//*****************************************************************************
//
// The value that is to be modified via bit-banding.
//
//*****************************************************************************
static volatile uint32_t g_ui32Value;

//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
    while(1)
    {
        //
        // Hang on runtime error.
        //
    }
}
#endif

//*****************************************************************************
//
// Configure the UART and its pins.  This must be called before UARTprintf().
//
//*****************************************************************************
void
ConfigureUART2(void)
{

    // Enable GPIOC
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
    while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOD)));
    //
    // Enable UART1
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART2);
    while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_UART2)));

        //ulock PD7
    HWREG(GPIO_PORTD_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
    HWREG(GPIO_PORTD_BASE + GPIO_O_CR) = 0xFF;
    //
    // Configure GPIO Pins for UART mode.
    //
    ROM_GPIOPinConfigure(GPIO_PD6_U2RX);
    ROM_GPIOPinConfigure(GPIO_PD7_U2TX);
    ROM_GPIOPinTypeUART(GPIO_PORTD_BASE, GPIO_PIN_6 | GPIO_PIN_7);

    //
    // Use the internal 16MHz oscillator as the UART clock source.
    //
    UARTClockSourceSet(UART2_BASE, UART_CLOCK_PIOSC);

    //
    // Initialize the UART for console I/O.
    //
    UARTStdioConfig(2, 115200, 16000000);
}
//*****************************************************************************
//
// This example demonstrates the use of bit-banding to set individual bits
// within a word of SRAM.
//
//*****************************************************************************
int
main(void)
{

    // Set the clocking to run directly from the crystal.
    //
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);

    //
    // Initialize the UART interface.
    //
    ConfigureUART2();

    UARTprintf("Hello this is TM4C123H6PM USART2!\n");
    UARTprintf("USART2 by stdio.h!\n");
    // Loop forever.
    //
    while(1)
    {
    }
}