【发布时间】：2020-06-03 10:11:37
【问题描述】：
我有一块 Arty Board，它使用 XUartLite 与我的笔记本电脑通信。
我想接收不同长度的多字节消息。第二个字节包含消息类型，然后我可以确定缓冲区中还有多少字节要检索。
在调整找到here 的代码后，我已经成功完成了这项工作（谢谢 Lance Simms）。
我的问题是，如果我在中断例程中使用XUartLite_RecvByte 方法来请求正确的字节数，因为它是一个阻塞调用，如果出现问题，那么我将被卡住等待一个永远不会到达 - 然后当下一条消息到来时，它将寻找错误的数据。
或者，如果我使用XUartLite_Recv 方法，它是非阻塞的，并指定字节数，除非我调试并逐步执行它不会检索字节，并且不会触发这些字节的另一个中断。
理想情况下，我希望在消息完成接收时触发RecvHandler，因为每1/2秒发送一次多字节消息。消息的长度可以是 7、8、10 或 13 个字节。
或者将指定的字节数设置为最大值（13），如果在接收到第一个字节后的一段时间后仍未填充，则使其超时。
在下面的示例中，我发送消息“foobar”。中断在第一个字节“f”之后调用RecvHandler方法，然后手动调用5次得到“oobar”。然后它会回显它。
//NAME:
// main.c
//
//PURPOSE:
// This C file is meant to be built with the Xilinx SDK and run as an
// ELF file on a Microblaze processor.
//
//AUTHOR:
// Lance Simms
// Note: Code uses Xilinx examples included with Vivado.
// https://lancesimms.com/Xilinx/VivadoFiles/VC707_Microblaze_UART_to_LED/main.c
//
//DATE:
// 01/09/17
//
/***************************** Include Files *********************************/
#include "xparameters.h"
#include <xil_printf.h>
#include <stdio.h>
#include "xil_exception.h"
#include "xuartlite.h"
#include "xintc.h"
#include "xgpio_l.h"
#include "xenv.h"
/************************** Constant Definitions *****************************/
/*
* The following constants map to the XPAR parameters created in the
* xparameters.h file. They are defined here such that a user can easily
* change all the needed parameters in one place.
*/
#define UARTLITE_DEVICE_ID XPAR_UARTLITE_0_DEVICE_ID
#define INTC_DEVICE_ID XPAR_INTC_0_DEVICE_ID
#define UARTLITE_INT_IRQ_ID XPAR_INTC_0_UARTLITE_0_VEC_ID
#define GPIO_REG_BASEADDR 0x40000000
/*
* The following constant controls the length of the buffers to be sent
* and received with the UartLite device.
*/
#define TEST_BUFFER_SIZE 500
/************************** Function Prototypes ******************************/
int SetupUartLite(u16 DeviceId);
int SetupInterruptSystem(XUartLite *UartLitePtr);
void SendHandler(void *CallBackRef, unsigned int EventData);
void RecvHandler(void *CallBackRef, unsigned int EventData);
void resetBuffer();
void printBuffer();
/************************** Variable Definitions *****************************/
XUartLite UartLite; /* The instance of the UartLite Device */
XUartLite_Config *UartLite_Cfg; /* The instance of the UartLite Config */
XIntc InterruptController; /* The instance of the Interrupt Controller */
/*
* The following buffers are used in this example to send and receive data
* with the UartLite.
*/
u8 SendBuffer[TEST_BUFFER_SIZE];
u8 ReceiveBuffer[TEST_BUFFER_SIZE];
/* Here are the pointers to the buffer */
u8* ReceiveBufferPtr = &ReceiveBuffer[0];
/*
* The following counters are used to determine when the entire buffer has
* been sent and received.
*/
static volatile int TotalReceivedCount;
static volatile int TotalSentCount;
int main()
{
//Variable definitions
int Status=0;
//Set up the UART and configure the interrupt handler for bytes in RX buffer
Status = SetupUartLite(UARTLITE_DEVICE_ID);
//Get a reference pointer to the Uart Configuration
UartLite_Cfg = XUartLite_LookupConfig(UARTLITE_DEVICE_ID);
//Print out the info about our XUartLite instance
xil_printf("\n\r");
xil_printf("Serial Port Properties ------------------\n\r");
xil_printf("Device ID : %d\n\r", UartLite_Cfg->DeviceId);
xil_printf("Baud Rate : %d\n\r", UartLite_Cfg->BaudRate);
xil_printf("Data Bits : %d\n\r", UartLite_Cfg->DataBits);
xil_printf("Base Addr : %08X\n\r", UartLite_Cfg->RegBaseAddr);
xil_printf("\n\r");
// Run
while (1){};
//End of program
return Status;
}
/****************************************************************************/
/**
*
* This function does a minimal test on the UartLite device and driver as a
* design example. The purpose of this function is to illustrate
* how to use the XUartLite component.
*
* This function sends data and expects to receive the same data through the
* UartLite. The user must provide a physical loopback such that data which is
* transmitted will be received.
*
* This function uses interrupt driver mode of the UartLite device. The calls
* to the UartLite driver in the handlers should only use the non-blocking
* calls.
*
* @param DeviceId is the Device ID of the UartLite Device and is the
* XPAR_<uartlite_instance>_DEVICE_ID value from xparameters.h.
*
* @return XST_SUCCESS if successful, otherwise XST_FAILURE.
*
* @note
*
* This function contains an infinite loop such that if interrupts are not
* working it may never return.
*
****************************************************************************/
int SetupUartLite(u16 DeviceId)
{
int Status;
/*
* Initialize the UartLite driver so that it's ready to use.
*/
Status = XUartLite_Initialize(&UartLite, DeviceId);
if (Status != XST_SUCCESS) {
return XST_FAILURE;
}
/*
* Perform a self-test to ensure that the hardware was built correctly.
*/
Status = XUartLite_SelfTest(&UartLite);
if (Status != XST_SUCCESS) {
return XST_FAILURE;
}
/*
* Connect the UartLite to the interrupt subsystem such that interrupts can
* occur. This function is application specific.
*/
Status = SetupInterruptSystem(&UartLite);
if (Status != XST_SUCCESS) {
return XST_FAILURE;
}
/*
* Setup the handlers for the UartLite that will be called from the
* interrupt context when data has been sent and received, specify a
* pointer to the UartLite driver instance as the callback reference so
* that the handlers are able to access the instance data.
*/
XUartLite_SetSendHandler(&UartLite, SendHandler, &UartLite);
XUartLite_SetRecvHandler(&UartLite, RecvHandler, &UartLite);
/*
* Enable the interrupt of the UartLite so that interrupts will occur.
*/
XUartLite_EnableInterrupt(&UartLite);
XUartLite_Recv(&UartLite, ReceiveBufferPtr, 1);
return XST_SUCCESS;
}
/*****************************************************************************/
/**
*
* This function is the handler which performs processing to send data to the
* UartLite. It is called from an interrupt context such that the amount of
* processing performed should be minimized. It is called when the transmit
* FIFO of the UartLite is empty and more data can be sent through the UartLite.
*
* This handler provides an example of how to handle data for the UartLite,
* but is application specific.
*
* @param CallBackRef contains a callback reference from the driver.
* In this case it is the instance pointer for the UartLite driver.
* @param EventData contains the number of bytes sent or received for sent
* and receive events.
*
* @return None.
*
* @note None.
*
****************************************************************************/
void SendHandler(void *CallBackRef, unsigned int EventData)
{
TotalSentCount = EventData;
}
/****************************************************************************/
/**
*
* This function is the handler which performs processing to receive data from
* the UartLite. It is called from an interrupt context such that the amount of
* processing performed should be minimized. It is called data is present in
* the receive FIFO of the UartLite such that the data can be retrieved from
* the UartLite. The size of the data present in the FIFO is not known when
* this function is called.
*
* This handler provides an example of how to handle data for the UartLite,
* but is application specific.
*
* @param CallBackRef contains a callback reference from the driver, in
* this case it is the instance pointer for the UartLite driver.
* @param EventData contains the number of bytes sent or received for sent
* and receive events.
*
* @return None.
*
* @note None.
*
****************************************************************************/
void RecvHandler(void *CallBackRef, unsigned int EventData)
{
if(ReceiveBuffer[0] == 'f') //Look at the start of the message to determine the remaining bytes.
{
ReceiveBufferPtr++; // 1 Byte has been found so increment the buffer ptr.
for(int i=1;i<6;i++){
ReceiveBuffer[i]=XUartLite_RecvByte(0x40600000U);
}
ReceiveBufferPtr+=5; //Non-blocking but it should be successful. so increment by 5.
}
printBuffer(); // print the contents of the buffer.
XUartLite_ResetFifos(&UartLite); // Reset the FIFOs
resetBuffer(); // Reset the contents of the buffer.
ReceiveBufferPtr = &ReceiveBuffer[0]; // Reset the pointer back to the start of the buffer.
XUartLite_Recv(&UartLite, ReceiveBufferPtr, 1); // Get ready to receive another byte.
}
void resetBuffer()
{
for(int i=0;i<TEST_BUFFER_SIZE;i++){
ReceiveBuffer[i]=0;
}
}
void printBuffer()
{
//return the message
XUartLite_Send(&UartLite,&ReceiveBuffer[0],6);
}
/****************************************************************************/
/**
*
* This function setups the interrupt system such that interrupts can occur
* for the UartLite device. This function is application specific since the
* actual system may or may not have an interrupt controller. The UartLite
* could be directly connected to a processor without an interrupt controller.
* The user should modify this function to fit the application.
*
* @param UartLitePtr contains a pointer to the instance of the UartLite
* component which is going to be connected to the interrupt
* controller.
*
* @return XST_SUCCESS if successful, otherwise XST_FAILURE.
*
* @note None.
*
****************************************************************************/
int SetupInterruptSystem(XUartLite *UartLitePtr)
{
int Status;
/*
* Initialize the interrupt controller driver so that it is ready to
* use.
*/
Status = XIntc_Initialize(&InterruptController, INTC_DEVICE_ID);
if (Status != XST_SUCCESS) {
return XST_FAILURE;
}
/*
* Connect a device driver handler that will be called when an interrupt
* for the device occurs, the device driver handler performs the
* specific interrupt processing for the device.
*/
Status = XIntc_Connect(&InterruptController, UARTLITE_INT_IRQ_ID,
(XInterruptHandler)XUartLite_InterruptHandler,
(void *)UartLitePtr);
if (Status != XST_SUCCESS) {
return XST_FAILURE;
}
/*
* Start the interrupt controller such that interrupts are enabled for
* all devices that cause interrupts, specific real mode so that
* the UartLite can cause interrupts through the interrupt controller.
*/
Status = XIntc_Start(&InterruptController, XIN_REAL_MODE);
if (Status != XST_SUCCESS) {
return XST_FAILURE;
}
/*
* Enable the interrupt for the UartLite device.
*/
XIntc_Enable(&InterruptController, UARTLITE_INT_IRQ_ID);
/*
* Initialize the exception table.
*/
Xil_ExceptionInit();
/*
* Register the interrupt controller handler with the exception table.
*/
Xil_ExceptionRegisterHandler(XIL_EXCEPTION_ID_INT,
(Xil_ExceptionHandler)XIntc_InterruptHandler,
&InterruptController);
/*
* Enable exceptions.
*/
Xil_ExceptionEnable();
return XST_SUCCESS;
}
提前致谢。
【问题讨论】：