Arty adjustable clock with Microblaze and Vivado SDK

[Weevil]

Dear all, i am really new in working with FPGA's and started with some microblaze application. So i build up a standard microblaze system with uartlite and some LED's. Also i generate a sine wave with the dds-compiler and now i want control the input clock of the dds-compiler for changing the output frequency. For this i started to use the axi-Timer (i don't know this is the best way for an adjustable clock) and started to write a C programm in the Vivado SDK software. Till now i don't get any output from the axi-Timer, maybe someone can help me...

Thank you! Following the C-code with already working LED's and uart communication:

 

Spoiler

 

#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 "xgpio.h" /* LED */

#include "xil_types.h"
#include "xtmrctr.h" /* timer lib */

/************************** 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
#define TMR_DEVICE_ID            XPAR_TMRCTR_0_DEVICE_ID

/*
 * The following constant controls the length of the buffers to be sent
 * and received with the UartLite device.
 */
#define TEST_BUFFER_SIZE        500

//Auto reload function
#define XTC_AUTO_RELOAD_OPTION        0x00000004UL

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

int SetupUartLite(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 */
 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];
 u8* CommandPtr       = &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;
    long i=0;

    //LED config
    XGpio gpio;
    u32 led;
    XGpio_Initialize(&gpio, 0);
    XGpio_SetDataDirection(&gpio, 1, 0x00000000); // set LED GPIO channel tristates to All Output

 

 

 

 

 

//code for controling the axi timer

    u32 frequence = 2000000;
    u8 channel_timer = 0;

    XTmrCtr Xtimer;

    //TIMER config
    XTmrCtr_Initialize(&Xtimer, 0);
    //XTmrCtr_InitHw(&Xtimer);

    XTmrCtr_SetResetValue(&Xtimer, channel_timer, frequence);

    XTmrCtr_Start(&Xtimer, channel_timer);

 

 

 

 

 

    //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 IDs : %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");

    while(i==0){

      //Print out the current contents of the buffer
      xil_printf("\n\r");
      xil_printf("Options ---------------------\n\r");
      xil_printf("a - Change the LED\n\r");
      xil_printf("b - Press a key to see its ASCII value show up on the LEDs\n\r");
      xil_printf("\n\r");

      //Check to make sure there is a new command to run
      while (ReceiveBufferPtr <= CommandPtr){};

      if (*CommandPtr == 'a'){
          xil_printf("A gedrueckt \n\r");
          led = 0x00000001;
          XGpio_DiscreteWrite(&gpio, 1, led);
      }

      else if (*CommandPtr == 'b'){
        CommandPtr++;
        xil_printf("Enter a key to see its value show up on the LEDs\n\r");
        led = 0x00000000;
        XGpio_DiscreteWrite(&gpio, 1, led);

        while (ReceiveBufferPtr <= CommandPtr){};

      }

      else if (*CommandPtr == 'c'){
          led = 0x00000000;
          XGpio_DiscreteWrite(&gpio, 1, led);

      }

      else {
        xil_printf("Not a valid command!\n\r");
      }

      //Increment to the next command
      CommandPtr++;

    }

    //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;
    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] = 1;
        ReceiveBuffer[Index] = 0;
    }

    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, ReceiveBufferPtr, 1);
    ReceiveBufferPtr++;
    TotalReceivedCount++;

    //If we've reached the end of the buffer, start over
    if (ReceiveBufferPtr >= (&ReceiveBuffer[0] + TEST_BUFFER_SIZE)){
      xil_printf("Resetting Receive Buffer. Please enter a new command!\n\r");
      ReceiveBufferPtr = &ReceiveBuffer[0];
      CommandPtr = &ReceiveBuffer[0];
      TotalReceivedCount = 0;
    }

}

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

/*****************************************************************************/
/**
*
* This function does a minimal test on the GPIO device configured as OUTPUT.
*
* @param    None.
*
* @return    - XST_SUCCESS if the example has completed successfully.
*            - XST_FAILURE if the example has failed.
*
* @note        None.
*
****************************************************************************/

 

 

 

[jpeyron]

Hi @Weevil,

We do not believe that the AXI TIMER is the right IP to create an adjustable clock. One of my co-works suggested trying the AXI dynclk IP.  Unfortunately, I do not have experience with this IP. I have reached out to more experienced engineers to see if they have additional input.

thank you,

Jon

[Weevil]

Hi Jon,

thank you very much for the tip with the dynclk IP! I tryed it and got an "place_design ERROR". Actual i don't know how to implement it the right way...

...I think the IP will do exact what i need.

 

 

 

[elodg]

@Weevil,

The error is due to an invalid connection. PXL_CLK_5X_O uses a BUFIO internally that cannot be routed to an external pin, which is what you are trying to achieve. To make it work, leave it unconnected and use PXL_CLK_O for internally clocking your DDS Compiler instance. These are particularities of the axi_dynclk IP due to it being meant for video applications. If you cannot make it work, see other options below.

For dynamic clock generation, you have two IP options: Xilinx Clocking Wizard with AXI-Lite interface or the Digilent axi_dynclk.

Advantages of Clocking Wizard: clock buffer options more suitable for non-video applications, documentation

Advantages of axi_dynclk: clock buffer options (BUFIO, BUFR) suitable for video applications, driver with VCO parameter calculation.

The Digilent axi_dynclk in the master branch of vivado-library does not have a standalone driver nor documentation. It does have a linux driver though. See issue https://github.com/Digilent/vivado-library/issues/14

However, there is a new  version of axi_dynclk with a standalone driver on a different branch: https://github.com/Digilent/vivado-library/tree/feature/axi_dynclk_driver

[Weevil]

Thank you all! It works perfect now.

I connected the Pmod R2R and can adjust the generated sine frequency with the dynclk. Finally i see the sine wave with my Analog Discovery Scope.

[jpeyron]

Hi @Weevil,

Glad to here you were able to get this working! 

cheers,

Jon