xuartlite_intr_example.c 분석

1. xuartlite_intr_example.c

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/******************************************************************************/
/**
*
* @file xuartlite_intr_example.c
*
* This file contains a design example using the UartLite driver (XUartLite) and
* hardware device using the interrupt mode.
*
* @note
*
* The user must provide a physical loopback such that data which is
* transmitted will be received.
*
* MODIFICATION HISTORY:
* <pre>
* Ver   Who  Date     Changes
* ----- ---- -------- -----------------------------------------------
* 1.00a jhl  02/13/02 First release
* 1.00b rpm  10/01/03 Made XIntc declaration global
* 1.00b sv   06/09/05 Minor changes to comply to Doxygen and coding guidelines
* 2.00a ktn  10/20/09 Updated to use HAL Processor APIs and minor changes
*		      for coding guidelnes.
* 3.2   ms   01/23/17 Added xil_printf statement in main function to
*                     ensure that "Successfully ran" and "Failed" strings
*                     are available in all examples. This is a fix for
*                     CR-965028.
* </pre>
******************************************************************************/

/***************************** Include Files *********************************/

#include "xparameters.h"
#include "xuartlite.h"
#include "xintc.h"
#include "xil_exception.h"
#include "xil_printf.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

/*
 * The following constant controls the length of the buffers to be sent
 * and received with the UartLite device.
 */
#define TEST_BUFFER_SIZE        100


/**************************** Type Definitions *******************************/


/***************** Macros (Inline Functions) Definitions *********************/


/************************** Function Prototypes ******************************/

int UartLiteIntrExample(u16 DeviceId);

int SetupInterruptSystem(XUartLite *UartLitePtr);

void SendHandler(void *CallBackRef, unsigned int EventData);

void RecvHandler(void *CallBackRef, unsigned int EventData);

/************************** Variable Definitions *****************************/

 XUartLite UartLite;            /* The instance of the UartLite Device */

 XIntc InterruptController;     /* The instance of the Interrupt Controller */

/*
 * The following variables are shared between non-interrupt processing and
 * interrupt processing such that they must be global.
 */

/*
 * 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];

/*
 * The following counters are used to determine when the entire buffer has
 * been sent and received.
 */
static volatile int TotalReceivedCount;
static volatile int TotalSentCount;


/******************************************************************************/
/**
*
* Main function to call the UartLite interrupt example.
*
* @param	None
*
* @return	XST_SUCCESS if successful, XST_FAILURE if unsuccessful
*
* @note		None
*
*******************************************************************************/
int main_UART_Interrupt(void)
{
	int Status;

	/*
	 * Run the UartLite Interrupt example, specify the Device ID that is
	 * generated in xparameters.h.
	 */
	Status = UartLiteIntrExample(UARTLITE_DEVICE_ID);
	if (Status != XST_SUCCESS) {
		xil_printf("Uartlite interrupt Example Failed\r\n");
		return XST_FAILURE;
	}

	xil_printf("Successfully ran Uartlite interrupt Example\r\n");
	return XST_SUCCESS;
}

/****************************************************************************/
/**
*
* 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 UartLiteIntrExample(u16 DeviceId)
{
	int Status;
	int Index;

	/*
	 * 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);

	/*
	 * Initialize the send buffer bytes with a pattern to send and the
	 * the receive buffer bytes to zero to allow the receive data to be
	 * verified.
	 */
	for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {
		SendBuffer[Index] = Index;
		ReceiveBuffer[Index] = 0;
	}

	/*
	 * Start receiving data before sending it since there is a loopback.
	 */
	XUartLite_Recv(&UartLite, ReceiveBuffer, TEST_BUFFER_SIZE);

	/*
	 * Send the buffer using the UartLite.
	 */
	XUartLite_Send(&UartLite, SendBuffer, TEST_BUFFER_SIZE);

	/*
	 * Wait for the entire buffer to be received, letting the interrupt
	 * processing work in the background, this function may get locked
	 * up in this loop if the interrupts are not working correctly.
	 */
	while ((TotalReceivedCount != TEST_BUFFER_SIZE) ||
		(TotalSentCount != TEST_BUFFER_SIZE)) {
	}

	/*
	 * Verify the entire receive buffer was successfully received.
	 */
	for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {
		if (ReceiveBuffer[Index] != SendBuffer[Index]) {
			return XST_FAILURE;
		}
	}

	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)
{
	TotalReceivedCount = EventData;
}

/****************************************************************************/
/**
*
* 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;
}

 

 

 

 

 

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2. 각각의 변수의 역활 및 의미

2.1) UARTLITE_DEVICE_ID (= XPAR_UARTLITE_0_DEVICE_ID)

#define UARTLITE_DEVICE_ID      XPAR_UARTLITE_0_DEVICE_ID

• FPGA 시스템내에 특정 모듈인 UARTLite 모듈을 식별하기 위한 Device ID

 

 

2.2) UartLite

/************************** Variable Definitions *****************************/

 XUartLite UartLite;            /* The instance of the UartLite Device */

• UARTLite 장치에 대한 드라이버를 나타내는 구조체의 인스턴스
• 인스턴스를 통해 UART 모듈을 초기화하고 설정하거나 데이터를 전송/수신하는 등의 제어 작업을 수행 가능

 

 

2.3) InterruptController

 XIntc InterruptController;     /* The instance of the Interrupt Controller */

• Interrupt Controller 모듈에 대한 구조체의 인스턴스
• 해당 인스턴스를 통해 Interrupt Controller 모듈을 초기화하고, 설정 등의 제어 작업을 수행 가능

 

 

2.4) UARTLITE_INT_IRQ_ID (= XPAR_INTC_0_UARTLITE_0_VEC_ID)

#define UARTLITE_INT_IRQ_ID     XPAR_INTC_0_UARTLITE_0_VEC_ID

• 해당 Vector ID는 Interrupt Controller에게 있어 다양한 Interrupt Vecotr ID 중에서 "해당 Interrupt가 어떠한 모듈로부터 전송되었는가?"를 나타내게 한다.
• 따라서 해당 XPAR_INTC_0_UARTLITE_0_VEC_ID 를 통해 수많은 Vector ID 중에서 UART 모듈로부터 발생했음을 식별할 수 있는 것이다.

 

 

 

 

 

 

 

---

 

 

 

 

 

3. 각 함수의 역활

3.1) XIntc_Connect 

/*
* 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;
}

• InterruptController 인스턴스를 통해 Interrupt Controller와 UART Interrupt Vector ID를 연결한다.
• UART Interrupt 발생시 "XUartLite_InterruptHandler"를 실행시키도록 해당 Handler를 Interrupt Handler로 설정
• Interrupt 처리 완료시 "UartLitePtr"를 Callback 함수로서 설정
  
  < 요약 정리 >
• Interrupt Controller가 UARTLITE_INT_IRQ_ID로 식별되는 UART 인터럽트와 연결됩니다.
• UART 인터럽트 발생 시, XUartLite_InterruptHandler가 호출되어 인터럽트 처리를 수행합니다.
• 인터럽트 핸들러는 UART 인스턴스(UartLitePtr)를 사용하여 적절한 작업(예: 데이터 송/수신)을 실행합니다.

 

 

 

3.2) Xil_ExceptionRegisterHandler

/*
* Register the interrupt controller handler with the exception table.
*/

Xil_ExceptionRegisterHandler(XIL_EXCEPTION_ID_INT,
                            (Xil_ExceptionHandler)XIntc_InterruptHandler,
                             &InterruptController);

• Interrupt Controller에서 예외처리가 발생할 경우, XIntc_InterruptHandler를 통해 예외처리를 실행한다.

 

 

 

3.3) XUartLite_SetSendHandler, XUartLite_SetRecvHandler

/*
* 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);

• UART 송신 완료시 발생하는 Interrupt에 대한 Handler로서 SendHandler를 등록
• UART 수신 완료시 발생하는 Interrupt에 대한 Handler로서 RecHandler를 등록

 

 

 

---

 

 

 

 

 

★★★★★★★★★★★★★★★ 중요 ★★★★★★★★★★★★★★★

Q) XUartLite_SetSendHandler와 XUartLite_SetRecvHandler 함수가 각각 UART통신에서 데이터 송신완료, 수신완료시 발생하는 Interrupt에 대한 Handler를 등록하는 것을 이해했다. 근데, SetupInterruptSystem 함수에서 XIntc_Connect 함수 선언시, XUartLite_InterruptHandler 라는 헨들러를 등록했는데, 왜 추가적으로 UART Interrupt에 대한 Handler를 등록하는 것인가? 

 이는 또 다른 Handler를 등록함으로서 UART Interrupt 발생한 부분에 대해서 다수의 Handler가 동작함으로서 충돌이 발생하는 것이 아닌가?

 

 

A) 

핸들러의 역할 차이

1. XUartLite_InterruptHandler (Interrupt Controller 핸들러)
   • 이 핸들러는 인터럽트 발생 시 호출되는 함수로, UART 장치에서 발생한 인터럽트를 관리하는 역할을 합니다.
   • 이 핸들러는 UART 모듈의 상태를 확인하고, 송신 또는 수신 이벤트가 발생했는지 판단합니다.
   • 따라서, 이 핸들러는 UART의 상태에 따라 적절한 송신 핸들러 또는 수신 핸들러를 호출하게 됩니다.
2. SendHandler 및 RecvHandler (UART 드라이버 핸들러)
   • 이 핸들러들은 UART 모듈에서 송신 또는 수신 완료 이벤트가 발생했을 때 실행되는 함수입니다.
   • 각각의 핸들러는 UART의 송신 FIFO가 비었을 때 데이터를 전송하거나, 수신 FIFO에 데이터가 있을 때 이를 처리하는 등의 작업을 수행합니다.

 

 

작동 흐름

• Interrupt 발생: UART에서 데이터 송신 또는 수신 이벤트가 발생하면,
  • Interrupt Controller는 먼저 XUartLite_InterruptHandler를 호출합니다.
  • 이 핸들러는 어떤 종류의 인터럽트가 발생했는지를 판별합니다.
  • 예를 들어, 송신이 완료되었다면 SendHandler를 호출하고, 수신이 완료되었다면 RecvHandler를 호출합니다.

 

 

 

핸들러 구조 요약

• XIntc_Connect는 UART 인터럽트가 발생했을 때의 진입점인 상위 핸들러를 등록합니다.
• XUartLite_SetSendHandler와 XUartLite_SetRecvHandler는 각각 송신 및 수신 이벤트에 대한 하위 핸들러를 등록합니다.
• 중복되지 않음: 핸들러는 서로 다른 역할을 수행하며, XUartLite_InterruptHandler는 인터럽트를 관리하는 통합 핸들러이고, SendHandler 및 RecvHandler는 송신 및 수신 작업을 수행합니다.

 

 

 

UART Interrupt에 대한 처리 흐름도