TM4C129芯片的UART

您好，您帮忙看下
while(!ROM_UARTBusy(UART2_BASE))
{
ROM_UARTCharPutNonBlocking(UART2_BASE, SendCode);//发送
}
我是想通过判断一个字节是否发送完成，如果上个字节发送完成后再接着发送下一个字节。这个用法测试时串口的数据没有发出来。

pei gong：

是这个：
while(ROM_UARTBusy(UART2_BASE))
{
ROM_UARTCharPutNonBlocking(UART2_BASE, SendCode);//发送
}

Susan Yang：

回复 pei gong:

我用TM4C123测试了一下，加了

while(ROM_UARTBusy(UART0_BASE))//add by susan { // delay here until transmission is complete }

可以成功发送，代码如下

//*****************************************************************************
//
// uart_echo.c - Example for reading data from and writing data to the UART in
//an interrupt driven fashion.
//
// 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_ints.h"
#include "inc/hw_memmap.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>UART Echo (uart_echo)</h1>
//!
//! This example application utilizes the UART to echo text.The first UART
//! (connected to the USB debug virtual serial port on the evaluation board)
//! will be configured in 115,200 baud, 8-n-1 mode.All characters received on
//! the UART are transmitted back to the UART.
//
//*****************************************************************************//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
}
#endif//*****************************************************************************
//
// The UART interrupt handler.
//
//*****************************************************************************
void
UARTIntHandler(void)
{uint32_t ui32Status;//// Get the interrrupt status.//ui32Status = ROM_UARTIntStatus(UART0_BASE, true);//// Clear the asserted interrupts.//ROM_UARTIntClear(UART0_BASE, ui32Status);//// Loop while there are characters in the receive FIFO.//while(ROM_UARTCharsAvail(UART0_BASE)){//// Read the next character from the UART and write it back to the UART.//ROM_UARTCharPutNonBlocking(UART0_BASE,ROM_UARTCharGetNonBlocking(UART0_BASE));//// Blink the LED to show a character transfer is occuring.//GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);//// Delay for 1 millisecond.Each SysCtlDelay is about 3 clocks.//SysCtlDelay(SysCtlClockGet() / (1000 * 3));//// Turn off the LED//GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);}
}//*****************************************************************************
//
// Send a string to the UART.
//
//*****************************************************************************
void
UARTSend(const uint8_t *pui8Buffer, uint32_t ui32Count)
{//// Loop while there are more characters to send.//while(ui32Count--){//// Write the next character to the UART.//ROM_UARTCharPutNonBlocking(UART0_BASE, *pui8Buffer++);}while(ROM_UARTBusy(UART0_BASE))//add by susan{// delay here until transmission is complete}
}//*****************************************************************************
//
// This example demonstrates how to send a string of data to the UART.
//
//*****************************************************************************
int
main(void)
{//// 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_FPUEnable();ROM_FPULazyStackingEnable();//// Set the clocking to run directly from the crystal.//ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |SYSCTL_XTAL_16MHZ);//// 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).//ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_2);//// Enable the peripherals used by this example.//ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);//// Enable processor interrupts.//ROM_IntMasterEnable();//// Set GPIO A0 and A1 as UART pins.//GPIOPinConfigure(GPIO_PA0_U0RX);GPIOPinConfigure(GPIO_PA1_U0TX);ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);//// Configure the UART for 115,200, 8-N-1 operation.//ROM_UARTConfigSetExpClk(UART0_BASE, ROM_SysCtlClockGet(), 115200,(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |UART_CONFIG_PAR_NONE));//// Enable the UART interrupt.//ROM_IntEnable(INT_UART0);ROM_UARTIntEnable(UART0_BASE, UART_INT_RX | UART_INT_RT);//// Prompt for text to be entered.//UARTSend((uint8_t *)"\033[2JEnter text: ", 16);//// Loop forever echoing data through the UART.//while(1){}
}

pei gong：

回复 Susan Yang:

好的，我按照您这样测试下。谢谢您。

pei gong：

回复 Susan Yang:

您好，您提供的这种方式确实是可行的，但是我想问下，标题中我那种方式不合理吗？还有就是我想通过判断忙闲来确定CPU是否需要去执行发送。如果该位忙，则跳出去执行其他任务。UART的发送需要占用CPU的时间对吧？

Susan Yang：

回复 pei gong:

若是可以的话，请您上传一下您的代码，谢谢。我对您的描述有些疑惑

pei gong：

回复 Susan Yang:

您好， 我明白了。下面是部分代码，单字节发送：

（1）while(1)

{

if(Uart2RX_OK==1)

       {

           Slave_B(Rx_Uart[UART2].RxBuffer,Rx_Uart[UART2].InPointer,UART2);

       }

}

（2）void Slave_B(uint8_t * ComRecBuffer,uint16_t Length,int iPort)

{

   if(ComRecBuffer[0]==Rx_Uart[iPort].self_Addr)

   {

       Tempaddr=(ComRecBuffer[2]<<8)+ComRecBuffer[3];

       Templen=(ComRecBuffer[4]<<8)+ComRecBuffer[5];

       if(ComRecBuffer[1]==0x03)

       {

           dataClass=CheckAdde(Tempaddr,Tempaddr+Templen-1);

           if(send_count_B==0)

           {

               YC_YX(Tempaddr,Templen,iPort,ComRecBuffer[1],dataClass);

            }

           else

           {

               if(send_count_B<Templen*2+5)

               {

                   YC_YX(Tempaddr,Templen,iPort,ComRecBuffer[1],dataClass);

               }

               else

               {

                   send_count_B=0;

                   Uart2RX_OK=0;

                   Rx_Uart[iPort].RxCounter=0;

                   Rx_Uart[iPort].InPointer=0;

               }

           }

       }

   }

}

（3）void Pack_YC_YX_Modbus(uint16_t StartValue,uint16_t Length,int iPort,uint8_t FCCode,uint16_t DataClass)

{

   unsigned int i=0;

   uint16_t getvalue;

   unsigned int CRCValue=0;

   Command[0]=Rx_Uart[iPort].self_Addr;

   Command[1]=FCCode;

   Command[2]=Length*2;

   for(i=0; i<Length; i++)

   {

       getvalue=SearchDataValue(StartValue+i,DataClass);

       Command[3+2*i]   = (getvalue>>8)&0xff;

       Command[3+2*i+1] = getvalue&0xff;

   }

   CRCValue=CRC16(Command,Length*2+3);

   Command[Length*2+3]=(CRCValue>>8)&0xff;

   Command[Length*2+4]=CRCValue&0xff;

   if(iPort==UART2)

   {

       if(send_count_B<Length*2+5)

       {

           TxFIFOFill_UART2(iPort,Command[send_count_B],1);

           send_count_B++;

       }

   }

   else if(iPort==UART6)

   {

       if(send_count_D<Length*2+5)

       {

           TxFIFOFill_UART6(iPort,Command[send_count_D],1);

           send_count_D++;

       }

   }

else

{

;

}

}

（4）void TxFIFOFill_UART2(int iport,unsigned char  SendCode,unsigned int Length)

{

unsigned int j=0,my_length;

my_length=Length;

UART2ENABLETX;

ROM_UARTCharPutNonBlocking(UART2_BASE, SendCode);//发送UARTCharPut  ROM_UARTCharPut

while(ROM_UARTBusy(UART2_BASE))//add by susan

{

// delay here until transmission is complete

}

UART2DISABLETX;

}

我的问题是：上述代码是UART2的执行过程，UART3与UART2执行过程和方法一致，如果中断来临时间点基本一致的话（未配置中断优先级），两个串口的输出从测试结果来看，UART3的输出必须是在等UART2完成后才执行。

上图1~6的执行是否占用CPU的资源呢？

pei gong：

回复 pei gong:

应该是均占用CPU时间，UART有两个FIFO，是每个UART都具有2个FIFO，而且均是独立的是吗？但是这两个FIFO都是通过寄存器UARTDR来访问的，那要是两个独立的UART，如果是同时响应了中断后，FIFO处理时是不能同时处理的是吧？