本帖最后由 xyz549040622 于 2015-11-25 16:32 编辑
使用 SysCtlDelay(ROM_SysCtlClockGet() / 3000);延时,并加入了测试ROM_SysCtlClockGet()值的代码,延时时间为1.1ms
- UARTprintf("Hello, world!\n");
- ui32Loop=0;
- ui32Loop=ROM_SysCtlClockGet();
- UARTprintf("%d\n",ui32Loop);
- ui32Loop=0;
- ui32Loop=SysCtlClockGet();
- UARTprintf("%d\n",ui32Loop);
整个源代码如下:
- //*****************************************************************************
- //
- // hello.c - Simple hello world example.
- //
- // Copyright (c) 2012-2014 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 2.1.0.12573 of the EK-TM4C123GXL Firmware Package.
- //
- //*****************************************************************************
- #include <stdint.h>
- #include <stdbool.h>
- #include "inc/hw_memmap.h"
- #include "inc/hw_types.h"
- #include "driverlib/debug.h"
- #include "driverlib/fpu.h"
- #include "driverlib/gpio.h"
- #include "driverlib/pin_map.h"
- #include "driverlib/rom.h"
- #include "driverlib/sysctl.h"
- #include "driverlib/uart.h"
- //#include "utils/uartstdio.h"
- //*****************************************************************************
- //
- //! \addtogroup example_list
- //! <h1>Hello World (hello)</h1>
- //!
- //! A very simple ``hello world'' example. It simply displays ``Hello World!''
- //! on the UART and is a starting point for more complicated applications.
- //!
- //! UART0, connected to the Virtual Serial Port and running at
- //! 115,200, 8-N-1, is used to display messages from this application.
- //
- //*****************************************************************************
- //*****************************************************************************
- //
- // The error routine that is called if the driver library encounters an error.
- //
- //*****************************************************************************
- #ifdef DEBUG
- void
- __error__(char *pcFilename, uint32_t ui32Line)
- {
- }
- #endif
- ////*****************************************************************************
- ////
- //// Configure the UART and its pins. This must be called before UARTprintf().
- ////
- ////*****************************************************************************
- //void
- ConfigureUART(void)
- {
- // //
- // // Enable the GPIO Peripheral used by the UART.
- // //
- ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
- // //
- // // Enable UART0
- // //
- ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
- // //
- // // Configure GPIO Pins for UART mode.
- // //
- ROM_GPIOPinConfigure(GPIO_PA0_U0RX);
- ROM_GPIOPinConfigure(GPIO_PA1_U0TX);
- ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
- // //
- // // Use the internal 16MHz oscillator as the UART clock source.
- // //
- UARTClockSourceSet(UART0_BASE, UART_CLOCK_PIOSC);
- // //
- // // Initialize the UART for console I/O.
- // //
- UARTStdioConfig(0, 115200, 16000000);
- }
- //*****************************************************************************
- //
- // Print "Hello World!" to the UART on the evaluation board.
- //
- //*****************************************************************************
- int
- main(void)
- {
- volatile uint32_t ui32Loop;
- //
- // Enable lazy stacking for interrupt handlers. This allows floating-point
- // instructions to be used within interrupt handlers, but at the expense of
- // extra stack usage.
- //
- // ROM_FPULazyStackingEnable();
- //
- // Set the clocking to run directly from the crystal.
- //
- ROM_SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ |
- SYSCTL_OSC_MAIN);
- //
- // Enable the GPIO port that is used for the on-board LED.
- //
- ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
- //
- // Enable the GPIO pins for the LED (PF2 & PF3).
- //
- ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_2);
- //
- // Initialize the UART.
- //
- ConfigureUART();
- // //
- // // Hello!
- // //
- UARTprintf("Hello, world!\n");
- ui32Loop=0;
- ui32Loop=ROM_SysCtlClockGet();
- UARTprintf("%d\n",ui32Loop);
- ui32Loop=0;
- ui32Loop=SysCtlClockGet();
- UARTprintf("%d\n",ui32Loop);
- //
- // We are finished. Hang around doing nothing.
- //
- while(1)
- {
- //
- // Turn on the BLUE LED.
- /* GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);
- //
- // Delay for a bit.
- //
- SysCtlDelay(50000000 / 3000);
- //
- // Turn off the BLUE LED.
- //
- GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);
- //
- // Delay for a bit.
- //
- SysCtlDelay(50000000 / 3000);*/
- GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);
- //
- // Delay for a bit.
- //
- SysCtlDelay(ROM_SysCtlClockGet() / 3000);
- //
- // Turn off the BLUE LED.
- //
- GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);
- //
- // Delay for a bit.
- //
- SysCtlDelay(ROM_SysCtlClockGet() / 3000);
- }
- }
可以看到,系统主时钟为50000000
延时时间如下:
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