EK-TM4C123GH6PM-UART2小练–使用PD6/PD7

//*****************************************************************************
//
// 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/fpu.h"
#include "driverlib/pin_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.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
ConfigureUART(void)
{// Enable GPIOCROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOD)));//// Enable UART1//ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART2);while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_UART2)));//ulock PD7HWREG(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);UARTConfigSetExpClk(UART2_BASE,16000000,115200,UART_CONFIG_PAR_NONE|UART_CONFIG_STOP_ONE|UART_CONFIG_WLEN_8);UARTEnable(UART2_BASE);
}

//*****************************************************************************
//
// 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.//ConfigureUART();//// Loop forever.//while(1){UARTCharPut(UART2_BASE,0xAA);}
}

xyz549040622：

串口的配置和其他串口差不多，值得注意的是，UART2使用的PD6、PD7中PD7是特殊功能IO引脚，需要解锁才可以作为串口使用的。需要加上下面这句代码才可以的

HWREG(GPIO_PORTD_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;HWREG(GPIO_PORTD_BASE + GPIO_O_CR) = 0xFF;

头文件中需要包含#include "inc/hw_gpio.h"这个文件，因为

GPIO_O_LOCK、GPIO_O_CR、GPIO_LOCK_KEY的定义是在hw_gpio.h中实现的。

Loren Lai：

回复 xyz549040622:

感謝你, 可以使用了!

Seven Han：

回复 xyz549040622:

谢谢分享！