cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Highlighted
Visitor
Visitor
320 Views
Registered: ‎06-03-2020

Multibyte UART messages of different lengths using UartLite

Hi!

Apologies in advance, I come from a background of high-level software languages, rather than hardware/firmware.

I have an Arty A7 Development board which I'm using to send and receive uart messages using UartLite.

I want to receive multibyte messages of differing lengths. The second byte contains the message type and I can then determine how many more bytes remain in the buffer to retrieve.

I have done this successfully after adapting the code found here (Thank you Lance Simms).

My issue is that, if I use the XUartLite_RecvByte method inside my interrupt routine to request the correct number of bytes, because it is a blocking call, if something goes wrong then I will be stuck waiting for a byte which never arrived - and then when the next message comes it will be looking for the wrong data.

Alternatively, if I use XUartLite_Recv method, which is non-blocking, and specify the number of bytes unless I debug and step through it doesn't retrieve the bytes, and doesn't trigger another interrupt for those bytes.

Ideally, I would like the interrupt to trigger the RecvHandler when the message has completed being received as each multi-byte message is being sent every 1/2 second. Messages can be 7,8,10 or 13 bytes long.

Or set the specified number of bytes to be the maximum (13) and have it timeout if it's not filled after a certain period from receiving the first byte.

In the example below I am sending the message "foobar". The interrupt calls the RecvHandler method after the first byte "f" and then it manually calls 5 times to get "oobar". Then it echos it back.

//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;
}

Also, I find that if I debug the whole message of "foobar" is returned, whereas if I let it run on "foob" comes through.

Thanks in advance!

0 Kudos
1 Reply
Highlighted
Moderator
Moderator
213 Views
Registered: ‎04-09-2019

Hi,

I have modified the code attached the same, please try the same and let me know.

//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)
{
XUartLite_Recv(&UartLite, ReceiveBuffer, 1); // Get ready to receive 1st byte
if(ReceiveBuffer[0] == 'f') //Look at the start of the message to determine the remaining bytes.
{
for(int i=1;i<6;i++){
ReceiveBuffer[i]=XUartLite_RecvByte(0x40600000U);
}
}

printBuffer(); // print the contents of the buffer.


XUartLite_ResetFifos(&UartLite); // Reset the FIFOs
resetBuffer(); // Reset the contents of the buffer.

}

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;
}

Regards,

Venu

0 Kudos